I am traveling again, this time to the opposite of South Dakota, in many ways, to California, but around Lake Tahoe, where they seem to have a fair amount of disdain for masks and lockdowns. Anyway, trying to keep up with the research and data. A number of interesting studies today, most around schools. A number of readers have asked me about some recent mask studies. All are modeling studies, and while I read them, I am not reporting on them because they aren’t actual research. In every one, the modelers build in an assumption of masks reducing transmission, so the studies are meaningless. You aren’t proving anything when you assume what you are testing is true.
In this study relating to understanding transmission, the researchers tried to actually measure aerosol presence in various types of spaces. (Medrxiv Paper) They used handheld particle counters in various public spaces. They found a fairly rapid drop in the concentration levels, depending on particle size. People moving in a public space stir up dust particles, which are a background level. I wonder if there can be interaction between these particles and those generated by human speech, breathing, coughing or sneezing. Good ventilation has an enormous impact on faster elimination of aerosols. Restrooms seem to have a particular risk of poorer ventilation.
Now on to school studies. First, a paper in the journal Pediatrics finds that day care centers did not make any substantial contribution to transmission of CV-19. (Ped. Study) Over 57,000 day care providers were surveyed to determine if they had been infected. 427 had been, but this was no different than the rate in the general population, and there was no association between their work and likelihood of exposure. While the risk of adults transmitting to children wasn’t studied, it is pretty clear that there isn’t an association of working in day care and getting CV-19.
Another study from Germany finds that cases did not increase significantly when children returned to school from the summer break. (Germany Paper) The researchers used differences in timing of school breaks to compare cases when school was and wasn’t in session. In fact the researchers found that cases declined slightly, which may just be coincidence, but it doesn’t appear associated with any change in mobility patterns after people came home from the breaks.
Somewhat in contrast, this study from Sweden finds some increased risk of transmission from children doing in-person school. (Medrxiv Paper) Sweden kept younger children in school but had older ones do virtual classes in the early part of the epidemic. No particular social distancing or mask wearing was used in the in-person classes. The researchers compared cases among parents of children in real school versus those with children doing virtual school and looked at cases among teachers of the two groups. They used only children in the last year of primary school and the first year of secondary school to make the closest possible comparison. Having a child in the real school was association with one more CV-19 case for 1000 parents. Teachers at the in-person school had about twice the risk of being infected as those doing virtual teaching. The partners of in-person teachers also may have had a slightly higher risk of infection. Overall, in-person school had a very minor effect on cases.
Here are interim results from an ongoing review of studies on transmission by children in schools. (Medrxiv Paper) the researchers examine a lot of the studies that have been previously reported on. Eleven studies were included and the quality was considered poor overall. The tentative conclusion was that there was a lower risk of transmission between students than to staff.
This study is kind of a well, doh, one. College students going back to campus caused a rise in cases. (Medrxiv Paper) It is a fear-mongering paper. The authors compare cases in counties with significant college presence and those without. They found 9% more cases in the college campus counties. They warned of an overwhelming of health care facilities. Hmmm, the best data suggests maybe five hospitalizations among all college students so far. Look, it is a good thing for the seriousness of the epidemic in the population as a whole, and for vulnerable sub-populations, if a lot of college students become infected, and there appears to almost no risk of serious illness to the group.
This paper is a little more concerning on return to college. (Medrxiv Paper) The study looks at LaCrosse, Wisconsin, which has three local colleges that returned to school in September. The researchers used genetic sequencing to supposedly trace transmission among college students to transmission to two local nursing homes. While the timing seems plausible for suggesting that transmission moved from the college group to the nursing homes, no direct evidence is given for how such transmission may have occurred. Since contact tracing is supposedly widespread, this is puzzling. Contemporaneous introduction at multiple parts of the community seems equally possible.