How do we get to herd immunity?

Felicia Wu, a John A. Hannah Distinguished Professor at Michigan State University, said in this great article:

The Los Alamos study estimated that 82% of the community needs to be immune to the novel coronavirus before all public health restrictions can be lifted, because their estimated R0 for SARS-CoV-2 is so high. The United States has a population of approximately 328 million people, so about 268 million people would have to develop immunity to the novel coronavirus in order to safely go out in society. Herd immunity for the seasonal flu is 55%.

Glossary

The last thing we need is another reason to be confused, so let’s be sure we’re all using the same terms.

I’ve put together the definitions below using several sources, in addition to the scientists who answered our questions. I’ll simply list the websites here for efficiency. If time permits, I’ll come back through and cite exactly which element of each definition comes from which source.

WHO.int, CDC.gov, dictionary.cambridge.org, healthline.com, npr.org, nature.com

Coronavirus: A type of common virus that infects humans, typically leading to an upper respiratory infection.

Coronaviruses are named for the crown-like spikes on their surface. There are four main sub-groupings of coronaviruses, known as alpha, beta, gamma, and delta.

Human coronaviruses were first identified in the mid-1960s. There are seven coronaviruses that infect people.

The Novel Coronavirus: A novel coronavirus is a new coronavirus that has not been previously identified. THE Novel Coronavirus is a common name for SARS-CoV-2, the virus causing coronavirus disease 2019 (COVID-19). The novel coronavirus is not the same as other coronaviruses that commonly circulate among humans and cause mild illness, like the common cold.

There are many types of human coronaviruses including some that commonly cause mild upper-respiratory tract illnesses.

SARS-CoV-1: Also called SARS, SARS coronavirus, SARS-CoV, and the original SARS, this is a virus identified in 2003 thought to be an animal virus from an as-yet-uncertain animal reservoir, perhaps bats, that spread to other animals (civet cats).

SARS-CoV-2: The virus that causes the disease COVID-19.

COVID-19: The disease caused by the SARS-CoV-2 virus. The new name of this disease is coronavirus disease 2019, abbreviated as COVID-19. In COVID-19, ‘CO’ stands for ‘corona,’ ‘VI’ for ‘virus,’ and ‘D’ for disease. Formerly, this disease was referred to as “2019 novel coronavirus” or “2019-nCoV”.

Seasonal Influenza: Also called the flu and the seasonal flu, seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world.

Contagious: Contagious diseases (such as the flu, colds, or strep throat) spread from person to person in several ways. One way is through direct physical contact, like touching or kissing a person who has the infection. Another way is when an infectious microbe travels through the air after someone nearby sneezes or coughs.

Sometimes people get contagious diseases by touching or using something an infected person has touched or used — like sharing a straw with someone who has mono or stepping into the shower after someone who has athlete’s foot. And sexually transmitted diseases (STDs) are spread through all types of sex.

Infectious: Infectious refers to diseases that are contracted through the environment, caused by bacteria or viruses. Infectious diseases that spread from person to person are said to be contagious.

Communicable: A communicable disease is a contagious one. The effect is external. If someone catches the illness, they can get sick and spread the pathogen—be it a cold, virus, or some other disease-causing agent—onto the next person. This can lead to small, isolated outbreaks or full-scale pandemics.

Antibody: a protein produced in the blood that fights disease by attaching to harmful viruses and bacteria so they are no longer functional and can be removed by other immune cells.

Antibody Test: Antibody tests identify people who have previously been infected with the coronavirus. They do not show whether a person is currently infected. Antibody tests should not be used to diagnose COVID-19.

PCR: PCR, or polymerase chain reaction, is a process that enables the exponential amplification of small amounts of genetic material until it can be detected with different tools in the laboratory. This technique has been used for decades in the study of DNA and RNA.

qPCR: Quantitative PCR or “Real-Time PCR” was developed as a method to estimate amounts of DNA or RNA in a biological sample. This technique is based on traditional Polymerase Chain Reaction (PCR).

Tests that rely on this technique can detect the merest traces of SARS-CoV-2 genetic material.

Virus: A virus is an infectious agent that can only replicate within a host organism.

Viral Load: A measure of how much virus is present in a person, once the person has been infected and the virus has had time to replicate in their cells. This amount changes over time, rising as infection progresses and declining as the person recovers.

R0 (or R naught): A mathematical term that indicates how contagious an infectious disease is. It’s also referred to as the reproduction number. As an infection is transmitted to new people, it reproduces itself.

R0 tells you the average number of people who will contract a contagious disease from one person with that disease. It specifically applies to a population of people who were previously free of infection and haven’t been vaccinated.

For example, if a disease has an R0 of 18, a person who has the disease will transmit it to an average of 18 other people. That replication will continue if no one has been vaccinated against the disease or is already immune to it in their community.

Three possibilities exist for the potential transmission or decline of a disease, depending on its R0 value:

• If R0 is less than 1, each existing infection causes less than one new infection. In this case, the disease will decline and eventually die out.

• If R0 equals 1, each existing infection causes one new infection. The disease will stay alive and stable, but there won’t be an outbreak or an epidemic.

• If R0 is more than 1, each existing infection causes more than one new infection. The disease will be transmitted between people, and there may be an outbreak or epidemic.

Importantly, a disease’s R0 value only applies when everyone in a population is completely vulnerable to the disease. This means:

• no one has been vaccinated

• no one has had the disease before

• there’s no way to control the spread of the disease

High Risk: High risk refers to people who are more likely to become severely ill if they are infected. For COVID-19, this is older adults and people with underlying medical conditions. 

Vulnerable Populations: Depending on the context, vulnerable populations in health care and research include the economically disadvantaged, racial and ethnic minorities, the uninsured, low-income children, the elderly, the homeless, children, prisoners, and people with chronic health conditions including severe mental illness and cognitive impairment.

Differentially Exposed Individuals: Those people impacted by social and institutional forces in ways that make them exposed to COVID-19 at rates that generally lead to the worst health outcomes. This term should be used in place of inaccurate yet frequently used terms like “harder-hit communities” and “high-risk communities.”

How do viruses work, and how do our bodies react to create symptoms?

Patrick Bardill, Ph.D.:

Viruses are infectious agents that can only replicate inside a living host cell. They consist of genetic material wrapped in protein and sometimes lipid membranes. This genetic material can be RNA or DNA, depending on the type of virus. A virus enters a host cell and uses the machinery in that cell to create more copies of itself. New viruses leave the host cell by either pushing through the host membrane, which leaves the new virus with a lipid membrane, or when the host cell dies and ruptures. 

Viruses can cause symptoms through stimulation of the immune system or damaging tissues in your body. It is usually a combination of these processes that produce disease pathology and symptoms.

For example, fever is a reaction from your body that raises your internal temperature to fight an infectious agent. However, in some individuals, the immune response can get out of control and be harmful to the person.

Jack Lipton, Ph.D.:

First thing to know is that viruses are not fully alive. A virus needs a living cell in order to reproduce and complete its function, which is to make more viruses.

When I was in high school, viruses were explained to me like this:

A virus is like a robot on a motorcycle.

The robot goes into a factory — a cell — and it takes it over. It changes around the machinery so that factory only produces robots and motorcycles. Then, after it uses up all the materials in the factory, it releases all of the robots on all of the motorcycles that the factory made, and they go to other factories to do the same thing all over again.

When we think of the illnesses that are produced by viruses, most of the symptoms you would associate with the illness come from your body’s immune response to this foreign invader. When your body finds a foreign invader – bacterium, virus – it uses the immune system to clean things up.

To do that, it uses chemicals that signal immune cells to move to the area. The process of releasing clean-up substances, which are toxic to the bacterium or virus, produces inflammation as a by-product. A fever is your body changing its thermostat setting to create an inhospitable place for invaders to live, but that process makes you feel sick. So your own immune system in its battle against invaders makes you feel sick. We call the by-products of these battle tactics symptoms.

The severity of someone’s illness from something like the flu or a coronavirus is often related to the magnitude of their immune response to the invader. If you have a very active immune system, you’ll produce a huge response to the infectious agent, and in the process of doing that, you’ll have worse symptoms.

Why did the SARS-CoV-2 virus become a pandemic, when other viruses don't?

Patrick Bardill, Ph.D.:

Generally speaking, there are a few properties of SARS-CoV-2 that contributed to it becoming a pandemic. It is a respiratory virus and easily transmitted through coughing or sneezing. It also appears to usually produce a very mild disease, with some people not realizing they are infected. Those people then interact with other individuals, passing the virus on without realizing they are sick. Finally, SARS-CoV-2 is a new virus for humans, meaning that before the present pandemic, no one had immunity to it from a previous infection. 

How infectious is Covid-19?

Patrick Bardill, Ph.D.:

When compared to more familiar diseases, this is much less contagious than measles, but more contagious than seasonal flu or norovirus.

This comparison is based on R-nought, or basic reproduction number. R0 is what R is at the start of an outbreak, before immunity or interventions. R0 more closely reflects the power of the virus itself, but it still changes from place to place. For example, R0 is higher in dense cities than sparse rural areas. R0 for seasonal flu is about 1.28; estimates of R0 for SARS-CoV-2 range from 2.2 to 5.7. Measles has an R0 of 18.

 R0 and R are different but have been conflated in most reporting. This has caused much confusion about what these numbers mean. 

 This resource has a very good explanation of R nought and R: https://ncase.me/covid-19/

Jack Lipton, Ph.D.:

It’s pretty infectious, from what we understand. At first, people were worried about it on surfaces. It doesn’t appear that touching a common surface is a particularly significant way for the virus to transmit. Some viruses are more hearty than others; their packaging are more conducive to living on surfaces.

For example, cold viruses are mild but are very infectious because they can last on door handles and other common touch areas. There is evidence that touch is important with coronaviruses, but more of the risks are associated with sharing air in the same space for an extended period of time with someone who is infected. That is because of microscopic droplets, which is why we’re all supposed to wear masks.

Can you address the concept of viral load, with real-world examples?

[In particular,] how the virus can be present but not necessarily in an amount that would cause someone to get sick. I’m thinking about how much is aerosolized and how long someone would have to be breathing it, or how much would need to be on a countertop and then picked up on hands then put into eyes/nose/mouth. Can you compare this to more familiar viruses, so laypeople might put the SARS-CoV-2 virus into context?

Chris Kemp, M.S.:

Viruses consist of little particles (singularly known as virions), and a certain number of them (the infectious dose) need to enter our system for us to get sick. At the moment, the infectious dose for SARS-CoV-2 is not known, but virologists are assuming the number is quite low, since it seems very transmissable. For context, the infectious dose for Hepatitis A is estimated at 10-100 particles, and the estimates for Norovirus are also in the 10-100 particle range. Most likely, SARS-CoV-2 is in this range too. But it's simply not known. When you think about infection, a sustained period of time in an enclosed space with an infected person dramatically increases the chance of infection. It's likely that, at some point, you've been around SARS-CoV-2 virions, but you need to get that infectious dose to become infected.

Alison Bernstein, Ph.D.:

There are many pieces to this question so I’m going to break it down into the individual topics.

Every pathogen has an infectious dose. For a virus, this is the number of individual viruses needed to infect someone. So for the virus to infect you, you need to be exposed to at least this amount of virus for the virus to take hold in your cells.

Viral load is a measure of how much virus is present in a person. It is the amount of virus present once a person has been infected and the virus has had time to replicate in their cells. This changes over time - going up as infection progresses and then declining as you, hopefully, recover.

In general, the higher your viral load, the worse your symptoms and the more contagious you are because you shed more whole viruses.

 However, there is a lot about this we don’t know for SARS-CoV-2 yet. Scientists expect the infectious dose is low, based on how easily it seems to spread through interpersonal contact.

Answers to questions about viral load and how it relates to how infectious this is and how contagious someone is at any given point in the disease course are still unclear. However, uncertainty on those details doesn’t change what we do know about this virus, or the recommendations that we know can stop the spread of the disease: masks, diligent hygiene and physical distancing.

All of the issues raised in the question about aerosols, droplets, and airborne go into how contagious this is and how specifically it spreads. The droplets and aerosols come from infected people and go into the air. Then they either get breathed in by another person or land on a surface. If the other person breathes in enough of this, they might be infected. If someone were to touch one of those surfaces, then touch their face, they might be infected. (The answer in the question about fomites explains how viruses on surfaces might be contagious.)

Scientists now think that spread is mostly through close contact with people and not from surfaces. Surface transmission is still possible, but isn’t its primary mode of transmission. For people living through this, the specific level of how much spread is from surfaces vs direct contact doesn’t change recommendations for diligent hygiene and masking.

Fortunately, taking these precautions gets around all the uncertainty about how long SARS-CoV-2 can survive on surfaces and what the mode of transmission is. No matter what those details are, we still need to take these precautions and always wash your hands well after coming into contact with something that may be contaminated. 

The airborne, aerosol, droplet question is important scientifically, and another example where scientists use these words differently than the public. In the very specific way that scientists mean it, SARS-CoV-2 is not airborne but is spread through aerosols and droplets. But again, the specifics don’t change what we need to do to stop the spread - wear masks and wash hands often.

Resources:

https://www.statnews.com/2020/04/14/how-much-of-the-coronavirus-does-it-take-to-make-you-sick/

https://www.vox.com/science-and-health/2020/5/22/21265180/cdc-coronavirus-surfaces-social-distancing-guidelines-covid-19-risks

Could you explain fomites - the objects that may transmit a virus?

I’m unclear on fomites. I’ve read that transmission through touch is low because a particular series of events has to happen for the virus to be transmitted this way, but in a NYTimes survey of epidemiologists, a surprising percentage take precautions when handling their mail. I was sanitizing all packaged groceries until a month ago when I read that there’s likely no need to, but with the current surge where I live (Austin), I’m wondering if I should start again and be more cautious regarding other fomites.

Alison Bernstein, Ph.D.: 

Fomites are inanimate objects that may transmit a virus, such as a doorknob. If a sick person touches a doorknob they may place viral particles onto it. Then, a healthy person could touch the doorknob and potentially transfer the virus to themselves.  For transfer to occur, the virus needs to be able to survive for some time on the surface. 

Several studies have examined how long SARS-CoV-2 can survive on objects. Depending on what the surface is - plastic, cardboard, metal -  we know that RNA from the virus can last between a few hours and a few days. What we don’t know is whether this means there is infectious virus present and if that is enough to infect you. So it is possible to transmit Covid-19 through a fomite, but this will depend on how much virus is present and how much time it has been there.

A good precaution that gets around all the uncertainty about how long SARS-CoV2 can survive on surfaces is to wash your hands well after coming into contact with something that may have been contaminated. 

Chris Kemp, M.S.:

Fomites are inanimate objects that can become contaminated with virus, so think: elevator buttons, door handles, etc. The field is still undecided on whether fomites are a major source of infection, but several recent papers do still consider them a possible secondary source of infection, far behind the much likelier route of airborne transmission. According to the CDC, the virus generally does not survive well on paper or cardboard. It lasts longest on steel but even then, its half-life on steel is around 5 hours or so. Short story: you're not likely to become infected from mail or groceries, and even less likely if you can leave them in a little quarantine spot for a few hours, or a day. For perishables, wipe them down if it makes you feel happier. 

Can asymptomatic people spread the disease?

I’ve heard that young people are asymptomatic, so they shouldn’t be worried about gathering. Can asymptomatic people spread the disease? Is this only theoretical, or are we seeing it happen?

Alison Bernstein, Ph.D.:

Young people do tend to have milder cases of Covid-19 than older people. However, young people may still develop serious or fatal cases of Covid-19. 

Yes, people without symptoms can spread the disease, as even if they do not feel sick they are able to shed the virus. Multiple studies have documented spread from people without symptoms and estimates for it are that as much as half of the cases of Covid-19 were from people who were not showing symptoms of the disease. 

The use of the words asymptomatic and presymptomatic has caused a lot of confusion, because these are words that are used differently by scientists and lay people. Regardless of which word is correct, what we need to know as people trying to make our way through this pandemic is that you cannot rely on your perception of health as an indicator that you are not infected. This is why it is important to wear masks, practice good hygiene and physical distance even if you feel healthy.

Irving Vega, Ph.D.:

The main reason for our lack of clarity on asymptomatic spreaders is that COVID-19 testing has been directed at symptomatic individuals. 

Interestingly, in the same households you can find asymptomatic and symptomatic individuals. In my lab’s community testing study, we identified asymptomatic individuals.  Upon testing their significant other, we found that they were infected too.  This was true for all asymptomatic cases we tested.

Comprehensive and accurate contact tracing with universal testing is required to answer the question about the role that asymptomatic individuals play in the spread of COVID-19.

Are asymptomatic people spreading the disease? In what ways?

Irving Vega, Ph.D.:

The main reason for our lack of clarity on asymptomatic spreaders is that COVID-19 testing has been directed at symptomatic individuals. 

Interestingly, in the same households you can find asymptomatic and symptomatic individuals. In my lab’s community testing study, we identified asymptomatic individuals.  Upon testing their significant other, we found that they were infected too.  This was true for all asymptomatic cases we tested.

Comprehensive and accurate contact tracing with universal testing is required to answer the question about the role that asymptomatic individuals play in the spread of COVID-19.

Resources:

What We Need to Understand About Asymptomatic Carriers if We’re Going to Beat Coronavirus: ProPublica’s health reporter Caroline Chen explains what the conversation around asymptomatic coronavirus carriers is missing, and what we need to understand if we’re going to beat this nefarious virus together. April 2, 2020

I’m not high-risk. Are essential workers, who are at higher risk of exposure due to their jobs, increasing my risk even when they’re wearing a mask?

Jack Lipton, Ph.D.:

Let’s be very clear: You are posing the risk to them. That they are there to help you is crucial to recognize.

When you show up without a mask and rely on elements of your privilege to protect you, you are exposing essential workers to the virus. You, and the next person, and the next person. That essential worker goes home to a household that is statistically more crowded and at higher medical risk. That essential worker does not have the same access to a physician or test that you do. That essential worker may not have the same access to health insurance that you do. The list goes on and on. So when you want to talk about sectors of our society that show higher rates of Covid-19, you’d better be prepared to talk about your role in risking their lives, not the other way around.

Do things like air purifiers, hepa filters, air scrubbers, and copper door handles mitigate any SARS-COV-2 virus transmission?

Alison Bernstein, Ph.D.:

Air scrubbers/air purifiers:

From the EPA: Will an air cleaner or air purifier help protect me and my family from COVID-19 in my home?

When used properly, air purifiers can help reduce airborne contaminants including viruses in a home or confined space. However, by itself, a portable air cleaner is not enough to protect people from COVID-19. When used along with other best practices recommended by the Centers for Disease Control and Prevention, operating an air cleaner can be part of a plan to protect yourself and your family. 

https://www.epa.gov/coronavirus/will-air-cleaner-or-air-purifier-help-protect-me-and-my-family-covid-19-my-home

HEPA filters: We don’t have good detailed information on this specifically for SARS-CoV2, but based on what we know about this other viruses, scientists can make some recommendations. HEPA filters can reduce viral load and can reduce transmission of measles and influenza. Coronoviruses themselves are smaller than the filter size in HEPA filters, but since it is spread mainly through droplets, which are large, they should be effective at filtering out viral particles. The placement of the HEPA filter relative to where people are coughing, talking or sneezing then becomes very important. The droplets need to be able to get to the filter to be filtered out. The other important consideration is air handling capacity — how many times in an hour can the system recycle the air in a given space.

Good resource: https://www.consumerreports.org/air-purifiers/what-to-know-about-air-purifiers-and-coronavirus/

Copper door knobs: This seems unclear at this point. Even if it does help kill viruses, is that complete or would it leave some viral particles present? But, with proper hand hygiene, this doesn’t matter. Wash hands after you touch a potentially infectious surface and it doesn’t matter what was on that surface. Wipe a door handle with a Clorox wipe and it’s safer than it was before.

I keep hearing people say, “Once we get back to normal.” This really bothers me. How do public health departments deal with changing the way the general public thinks?

I keep hearing people say, “Once we get back to normal.” This really bothers me, because it seems like that implies they want to forget this ever happened and go back to the way things were — which in turn drives them to act more and more “normal” when it’s not immediately in front of their faces. (For example, everyone who started to go to bars as soon as the state began to reopen.) How do public health departments deal with changing the way the general public thinks? We all came around to seat belts and non-smoking bars somehow.

Chris Kemp, M.S.:

Public health departments can only communicate the risk, suggest the appropriate ways to respond, and hope that people comply with the recommendations. In this case, public health departments have been undermined at the federal response, and often by political leadership at the state level, too.

Jack Lipton, Ph.D.:

Public health departments attempt to communicate best practices for staying infection free, but government agencies are not the agents of change. People are. We need to accept that there will be a new normal. As an example, Dr. Fauci said he thinks shaking hands should stop — forever. Do you wonder, throughout human history, how many people have transmitted an infection by handshake, and how many people have died as a result?

Normal behavior is, by definition, the thing that most people do. Therefore, we are now in need of a new set of normal behaviors. How we greet each other, our hygiene, how close we stand to each other, and our wearing of PPE, for example. A new normal means changing some — not all — of our many, many behaviors. Yes, change can be uncomfortable. However, if we do not adapt to our new circumstances, people will die. The trade-off isn’t so significant — in fact, I would urge everyone to really think about this any time they encounter someone who pushes against these simple changes. Recall the many times we as a people have had to change several significant behaviors to accommodate wars, depression, technology, and so on. “Normal” does not grant us a lack of change — change will happen in some way. Developing a new normal gives us some measure of control over how that change happens. These adaptations are not hard, but they require making thoughtful choices.

I recently had someone reflexively reach out to shake my hand. If I had only reacted and hadn’t thought about it — if I hadn’t made a conscious choice to air-elbow-bump instead — I would have been perpetuating a behavior that needs to end. If I wear a mask to a market and other people aren’t wearing theirs, I might feel foolish for wearing mine. However, if I take my mask off, another person might feel foolish for keeping theirs on. I am then contributing to a normal that values remaining unchanged even if it means people die because of it.

Our state recently began its reopening process, and I am angry beyond measure when I see masked workers at restaurants, bars, and markets, while the patrons choose not to wear masks. I’m sick of being stuck at home, too; I want the economy to come back, too. However, the solution is not to “finally get back to normal.” If you go out, do it making conscious choices that create a new normal. Quit shaking hands. Wear your mask. Stay six feet apart. Your actions cascade others’ actions, and while they may seem small to you in the moment, every new behavior we can offer to one another means fewer people suffer the unimaginable, preventable change that comes from the death of someone we love.

Resources:

Felicia Wu, John A. Hannah Distinguished Professor at Michigan State University, explains the importance of adhering to public health guidelines: https://www.canr.msu.edu/news/msu-public-health-expert-discusses-practices-for-mitigating-spread-of-novel-coronavirus

What should we be thinking about regarding our two college students who will return to their dorms in the fall? (Both out of state.)

Alison Bernstein, Ph.D.:

Will everyone have a single? How can they have enough space for all the students if everyone is in a single? What are they doing for testing and tracing on campus? What is the plan if someone gets sick? Where will they quarantine people? Are students and professors required to wear masks in classrooms and other common areas? Will hand sanitizer and disinfectant be available in all bathrooms, entrances, and in the hallways of dorms? What are they doing about meal service?

These are just a few of the questions I would have if my kids were college-aged.

Jack Lipton, Ph.D.:

I think there’s a lot of risk for students going to or going back to college, particularly in high-density housing. Much like the cruise ships and aircraft carriers that saw Covid-19 rip through them, students in high-density housing will be at a high risk for transmission. That doesn’t necessarily mean they will become very ill, but they will endanger others who are susceptible to becoming very ill, including faculty, staff, and fellow students who are at a high risk of severe response to infection.

So what do we do?

• Get specifics. Any plan is worthless without how, when, and by whom it will be executed.

• Be sure you find out what the college’s communication plan will be, what they’ll include in their reports, and how often they’ll send them.

• Find out what the isolation plans are. Is there enough space for the number of people who may need to be isolated? What is the college basing that space decision on? How will isolated students be cared for (meals, cleaning, space to study, fresh air, online classes, etc.), so that their needs are met but employees are not risking exposure?

• Will the college conduct contact tracing? If so, how?

• Find out about support staff and faculty. What are the plans the institution is making for them? What happens to them affects the students, and vice-versa.

The number one thing we can do is systematic screening. In order for us to be able to know where the infections are, we need to do interval screening on a regular basis. One of the options we’re examining at MSU is testing all of the people who fall into high-risk categories (students who live in dorms, Greek housing, and university apartments; athletes; faculty and staff, etc.) every two weeks, looking for trends in certain dorms, staff positions, dining halls, etc. This will help us to control what we can control. For example, it could tell us that the air supply system is particularly bad in one building compared to another; using that data, we can make adjustments that will help protect more people. We can also contact people who have spent a great deal of time there and send them out for clinical tests and employ contact tracing teams. When we test every person who lives in a high-density environment, along with every staff and faculty member, on a rolling, two-week basis, we’ll also identify the asymptomatic spreaders who might turn a campus into a hot spot.

Finally, one of the things that we must address is the personal responsibility of every student.

We know the frontal lobes of college students are not fully formed. Their propensity for risk-taking is very high. That can show up in risky behaviors without thinking of the consequences.

Addressing this issue as it relates to the SARS-CoV-2 virus requires an entire campus-wide campaign to educate and train students, getting them socially acculturated to doing the right thing, and minimizing their risk of hurting others. We have to help them make better choices that are based on their commitment and care for the entire campus community, not just themselves.  

As a college professor, academic researcher, and the co-chair of MSU’s Return to Campus Testing Subcommittee, these are the things I would hope incoming students and their parents would be asking about.

How much of an issue might it be for kids to play with neighborhood friends or a select group of other friends outside?

Chris Kemp, M.S.:

All activities carry some risk, but some clearly carry more than others. Consider the risks carefully. The best approach to controlling the virus is still strict social distancing. If you have some trusted families that have been social distancing in the same way you have, and share your concerns, you might be able to make a more informed choice and arrange for the kids to enjoy some playtime that doesn't require physical closeness, like kicking a ball around or riding bikes. Otherwise the risks can outweigh the benefit.

Alison Bernstein, Ph.D.:

Outside is lower risk than inside. But this also depends on many things because the issue is really about close contact between people. 

How are the kids playing? Are they playing close or can they play apart? Are they going on a bike ride together? This is less contact than playing basketball. 

Is everyone wearing masks? If the kids are wearing masks, many of these other concerns are greatly reduced.

Are the kids playing everyday, all day, or for an hour? Exposure is also a function of time. The longer the interaction, the greater the risk. Making these events infrequent can reduce the risks of these interactions.

How is your community behaving? Did your neighbors just take a trip to a state that is currently a hotspot like Florida or Arizona? If the people around you are wearing masks and abiding by physical distancing recommendations, their risk of transmitting the disease is lower and I would tolerate the risks of playing more. But if I knew that my neighbors were actively not doing all the thing they should be doing to protect our community, then I would be a lot less permissive in letting my kids play. 

Unfortunately, as soon as school opens in the fall, I will no longer have this control and our success as a community will be dictated by the least compliant among us.

Good graphic here ranking activities, I’d put kids playing outside with friends between yellow and orange depending on the specifics: https://www.vox.com/science-and-health/2020/5/22/21265180/cdc-coronavirus-surfaces-social-distancing-guidelines-covid-19-risks

How much of an issue is a park playground?

Alison Bernstein, Ph.D.:

There are two pieces to this question. First, are the surfaces on the playground equipment contaminated and a potential source of infection? Second, how many people are at the playground and are they wearing masks?

Let’s tackle surfaces. All the data is in lab settings so we don’t really know what happens outside with rain and sun and the elements. CDC recommends that playgroup equipment be cleaned, but not disinfected. However, many municipalities don’t have the funds to do this. I would guess that the risk of getting COVID-19 from a playgroup surface is low, though. Of course, on a crowded playground with people not wearing masks, that risk goes up, because more people are potentially depositing virus on those surfaces.

 The bigger concern to me, as with all things coronavirus, is people. Is the playground crowded? Can you and your kids maintain distance with the people who are there? If not, are people wearing masks? Did you bring your hand sanitizer to clean your and your kids’ hands regularly? This to me is the bigger concern and is highly dependent on the behavior of people around you.

This is complicated by kids being kids. Kids touch everything. They put things in their mouths. They will want to be close to their friends, especially after months apart. They might not leave their masks on or they will fall off as the play. All of these make this a complicated thing to assess.

Personally, I would go to the playground only if there were few people and we could mostly maintain distance, if all of those people were wearing masks, and if my kids let me sanitize their hands regularly and didn’t touch their faces. Fortunately, I live in the suburbs, have a nice backyard and my kids have mostly outgrown playgrounds. This calculation will be different for people who don’t have a yard or live in a city in small apartments with little access to the outdoors, but it is a calculation that should be made.

Good resource: https://www.nytimes.com/2020/06/11/parenting/playgrounds-reopen-safety-coronavirus.html 

Chris Kemp, M.S.:

All activities carry some risk. You have to weigh the risk of the activity against the benefit. Outside time is really important. I see a lot of kids playing on my local park playground. From an abundance of caution, I have not allowed my own children to visit the playground yet and I'm not sure when I will. They're just as happy throwing a ball or riding a bike, both of which have almost zero risk.

What do you think the mitigation strategies should be for businesses and interactions that have a high potential for spread in a small space?

Below you’ll find specific instances asked about on social media.

Chris Kemp, M.S.:

Hot yoga…We’ve been researching how the spread may multiply when in a room with a single speaker for over 30 minutes, and its potential exponential effects. 

A hot yoga class clearly represents a risk. It provides perfect conditions for viral transmission. I wouldn't consider it without at least knowing more about the studio's mitigation strategies in detail and, even then, I don't see how they're good enough. You'd need masks on everyone, social distancing, improved airflow, and pre-class symptom monitoring. Seems like an excessive risk in an environment that provides all the right conditions for infection.

Question on behalf of an auto repair shop wanting to minimize risk to workers and customers: What are the exposure risks inside of people’s cars? Is it necessary for the workers to wear a mask when inside customers’ vehicles? Sanitizing interiors could ruin leather and other surface materials, yet there are several points of contact (doors, steering wheel, seatbelt, etc.). Employees wash their hands before and after getting into a vehicle and they distance inside the shop, but we also have a combined office/waiting room where we cannot physically distance (same for many similar repair shops). 

I think it is necessary to wear masks inside customers' cars. The exposure risks are difficult to quantify, so rely on strategies that limit risk. Clorox wipes or an equivalent product should sanitize the surfaces you’re able to use them on adequately. My suggestion for waiting rooms is to close them temporarily, or strictly limit the number of people allowed in the waiting area at a time so that they can maintain social distancing. Yes, it's inconvenient but there are lots of inconveniences at this time, and some of them aren't worth ignoring.

 At our bike shop, we’re taking a lot of time to sanitize after test rides, and are considering opening up the bike rental portion of our business. Can we realistically do this safely?

All activities carry risk. Can you guarantee complete safety? Definitely not. Can you try to mitigate risk? Yes. Wear masks always, maintain social distance, try to make payment and all other aspects of the business contactless, thoroughly sanitize bikes between customers. Let your customers know what you’re doing, so they take some responsibility for the risk.

What’s the prediction on when we’ll be able to safely date? Should we plan for a “new dating normal,” and if so, what do you think it will look like?

Unfortunately, activities like dating will really be impacted until we have a dependable vaccine to the virus, and any other answer is unrealistic. At the very least, the "new dating normal" should include real honest conversations about risk, concerns, and whether each of you is in the same place and taking the same approach to the virus regarding masks, and social distancing, and other measures. Not romantic, I know.  

Alison Bernstein, Ph.D.:

The general guidelines apply in all these cases. There are good hygiene practice — wearing masks all the time and physical distancing as much as possible. Hygiene involves frequent cleaning and disinfecting of surfaces that may have been contaminated and frequent hand washing/sanitizing. Mandating mask wearing can be hard, even if your local or state government has already mandated this, because enforcement is difficult. But high compliance on mask wearing is one of our best defenses against this pandemic. Physical distancing should be practiced as much as possible, but needs for distancing can be reduced if compliance on everything else is high.

CDC has guidelines for a variety of specific activities and institutions here https://www.cdc.gov/coronavirus/2019-ncov/community/index.html

Personally, I cannot imagine going back to any sort of group fitness class any time soon. I normally do a yoga class once a week, and Orange Theory twice a week. I will not be going back to these in the near future. If they mandate masks and limit enrollment and our local R is below 1, I might be comfortable going back, but as of right now, you couldn’t pay me enough to take this risk.

For auto repair shops, given everything we talked about with surfaces and fomites, the risk of exposure from the car interior is relatively low especially if the car sits for a while before an employee enters the car. Time is your friend here.

Points of high contact - steering wheels, seatbelts, door handles - should be wiped down. Even if disinfectant would damage surfaces, it is important to remember that soap is also effective at disrupting the coronavirus and the physical action of wiping can also remove viruses. If employees wear masks to protect each other and protect customers, wipe down surfaces when the car arrives, wash their hands after touching those high contact surfaces and avoid touching their faces, it seems possible to mitigate most of the risks. 

The combined office/waiting room might need to be closed, access limited, or mask wearing and regular disinfecting strictly enforced. Thinking creatively about how to use these spaces is important at this time. 

I would rent a bike if everyone was wearing a mask and I could wipe down the bike before taking it out.

I think there will be a new normal for everything, including dating. It seems a lot to ask for a two-week quarantine prior to a first date, but in the absence of regular testing this is the only guarantee that one person is not infected. There might be a lot more getting to know each other remotely prior to meeting in person and a discussion of what measures you are each taking. 

Date activities could be planned with the same concerns in mind as every other activity, according to the risk categories outlined in this Vox graphic:

https://www.vox.com/science-and-health/2020/5/22/21265180/cdc-coronavirus-surfaces-social-distancing-guidelines-covid-19-risks

Perhaps a socially distanced walk with masks, a picnic. This is obviously easier in the summer and will be more difficult as the weather turns colder.

The question of physical intimacy is much more difficult because, by definition, this violates all rules of physical distancing. Ideally, dating interactions should be approached with the same precautions as all your other interactions. This obviously makes spontaneity difficult.

Are people who don’t wear masks endangering themselves?

Are people who don’t wear masks endangering themselves? I’m thinking particularly of the extreme ends of the spectrum – 20-somethings and senior citizens who feel that masks and stepped-up hygiene practices are unnecessary.

Alison Bernstein, Ph.D.:

People who don’t wear masks are endangering their friends, families, neighbors and communities. Your masks protects the people around you and their masks protect you. Eventually, this does come around to endangering themselves as their refusal to wear a mask will help the virus continue to spread throughout the community.

I think that appealing to civic duty, shared responsibility and protecting the people in your community who are high-risk or less able to physical distance because of their jobs or living situations may help to convince people to wear masks. 

Why does Covid-19 affect kids, young adults, and older adults so differently?

I’ve heard that kids might get heart symptoms/conditions from Covid, young adults might have strokes, and older adults are doomed. Why does Covid-19 affect kids, young adults, and older adults so differently?

Alison Bernstein, Ph.D.:

These reasons behind these differences remain unclear. There is a new study that looked at the cells in the lining of kids’ noses compared to adults. They found that in kids, these cells had less gene expression of the ACE2, which encodes the protein that SARS-CoV2 is thought to use to get into cells. So if kids, in general, have less of this protein, the virus might just not be able to get into the host cells. But this is very preliminary as they haven’t looked at actual protein levels or reduced activity of ACE2. Some people also suspect that the differences in adult and child immune systems might contribute. But the science in this area is still very new and developing.

 https://jamanetwork.com/journals/jama/fullarticle/2766524

It is also important to remember that risk is a population-based concept. So while more old people get severe cases and more young people have mild cases, there are also examples of mild cases in old people and severe cases in children. We just don’t have enough information to predict who those individuals within a population will be. This means we all have to be vigilant.

What’s the deal with blood types? Women vs. men?

This comes from preliminary data in a study by 23andMe. There may be a 9-18% reduction in risk for people with Type O blood. As they summarize on their website:

• The preliminary data suggest that O blood type appears to be protective against the virus when compared to all other blood types. 

• Individuals with O blood type are between 9-18% percent less likely than individuals with other blood types to have tested positive for COVID-19, according to the data. 

• There appeared to be little differences in susceptibility among the other blood types. 

• These findings hold when adjusted for age, sex, body mass index, ethnicity, and co-morbidities.

• Although one study found the blood group O only to be protective across rhesus positive blood types, differences in rhesus factor (blood type + or -) were not significant in 23andMe data. Nor was this a factor in susceptibility or severity in cases.

• Among those exposed to the virus — healthcare and other front line workers — 23andMe found that blood type O is similarly protective, but the proportion of cases within strata is higher.

The change in risk is also very modest. When they graph the percentage of cases in each of the blood types, you can see this clearly.

Again, a reminder that risk is population-based so even if you are in a lower risk group, you cannot know what your outcome would be. While this is intriguing scientifically, it seems of little use for the public at the moment.

https://blog.23andme.com/23andme-research/23andme-finds-evidence-that-blood-type-plays-a-role-in-covid-19/

Do we have a baseline responsibility to not "go back to normal?"

Do we have a baseline responsibility to not go back to “normal” — to think of our climb out of the Covid-19 pandemic in a different way, to impact a more realistic outcome?

Alison Bernstein, Ph.D.:

This is another ethical question. Personally, it is my opinion that we do.

An example of one such effort is efforts to create new stock photo images of people in masks. Another is encouraging and expecting role models to demonstrate the “new normal.” For better or worse, people listen to what influencers and celebrities have to say about all sorts of things about which they have no expertise. They could use their platforms for good, by posting about how they are distancing, posting pictures of themselves in masks, amplifying accurate messages. We can all do the same within our own social networks. The words we use and the images we see matter. I would like to see more attempts to instill a sense of civic duty and responsibility to our communities to keep each other safe. This pandemic is a clear case where individual action is insufficient to address the problem. The only way to protect myself is to protect you and the only way for you to protect yourself is to protect me

How should the average person weigh social connection against risk?

Chris Kemp, M.S.:

Very carefully. Everything carries some risk, so it's better to try to find ways to connect socially without adding unnecessary risk. We know enough about the virus that outdoor activities, while observing social distancing measures, are obviously much better than going to a crowded bar without a mask. If it feels risky, it is risky.

Alison Bernstein, Ph.D.:

Social isolation is not good for us. We need to find ways to have social connections while practicing good risk mitigation strategies. We know what needs to be done to allow us to be social without endangering our progress is slowing the spread.

Wearing a mask and frequent hand washing goes a long way to mitigate risk. Combined with sitting far apart if you can’t wear a mask (while eating for example), this can go a long way to mitigating risk to allow us to reconnect with friends.

An idea that is emerging is the quarantine bubble or “quaranteam,” where you talk frankly with friends about merging your bubble for a period of time. This requires trust and honesty.

Melissa Hawkins, an epidemiologist, writes about how to create your own:

First, everyone must agree to follow the rules and be honest and open about their actions. Individual behavior can put the whole team at risk and the foundation of a quaranteam is trust. Teams should also talk in advance about what to do if someone breaks the rules or is exposed to an infected person. If someone starts to show symptoms, everyone should agree to self-isolate for 14 days.

Second, everyone must decide how much risk is acceptable and establish rules that reflect this decision. For example, some people might feel OK about having a close family member visit but others may not. Our family has agreed that we only visit with friends outside, not inside, and that everyone must wear masks at all times.

Finally, people need to actually follow the rules, comply with physical distancing outside of the quaranteam and be forthcoming if they think they may have been exposed.

Additionally, communication should be ongoing and dynamic. The realities of the pandemic are changing at a rapid pace and what may be OK one day might be too risky for some the next.

This is explained in more detail in her recent article: https://theconversation.com/quarantine-bubbles-when-done-right-limit-coronavirus-risk-and-help-fight-loneliness-140134

Jack Lipton, Ph.D.:

Our mental health and our need for social interaction is extremely important. Children I’ve interacted with over the past few months — their response to isolation is deeply concerning. As we are safely able to do so, we should try to expand the group of people who can physically interact with our kids as long as they’re agreeing to some ground rules — and taking those ground rules seriously.

One of the main risks that we all take is interactions with our friends and family members whose exposure is unknown. We’ve all been isolating in place a long time, and if we want to expand our interactions, we can try to do so responsibly by making clear and defined agreements with others. My family has come up with The Circle, which sounds like it’s similar to a quaranteam.

As you make your own plan, consider that one person in a room by themselves all the time will not get sick. When you bring in another person, that person has to have a clear understanding of where they’ve been and what they’ve risked — whether it’s going to the market, an appointment, work, daycare, etc. Every person you bring into your circle should be very aware of and transparent with their personal level of interaction with others. Every person you bring in must also agree to the same precautionary practices, and every person must agree to isolate if they encounter an increased level of risk. If they cannot bring those elements to your circle, they can’t be in the circle — that’s it.

Even though it may seem too simple or awkward to do so, have a circle-wide conversation that covers the basics of the virus, the disease, the risks, and the plan.

If we get to a point where we’re regularly testing everyone, not only the symptomatic, then we won’t have to worry so much about this. Until then, figure out your circle or quaranteam. If someone wants to connect socially but they’re not able to follow the group’s rules, or you feel they’ll violate them despite agreeing to them, it’s a clear “no.” You can reconnect once it’s safer to do so.

I can’t stress enough how important it is to establish your boundaries now. In the moment is a terrible time to consider how you and your family should handle interactions during a pandemic. Defining them now will better prepare you to prepare others for when you say “no,” and it will help you have the language you need versus fumbling when it matters.