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.