Less than three months ago, the Centers for Disease Control published a mostly-ignored, large-scale study of Covid-19 transmission in US schools which concluded that while masking then-unvaccinated teachers and improving ventilation was associated with lower levels of virus transmission in schools – social distancing, classroom barriers, HEPA filters, and forcing students to wear masks did not result in a statistically significant benefit.
A few major news outlets covered its release by briefly reiterating the study’s summary: that masking then-unvaccinated teachers and improving ventilation with more fresh air were associated with a lower incidence of the virus in schools. Those are common-sense measures, and the fact that they seem to work is reassuring but not surprising. Other findings of equal importance in the study, however, were absent from the summary and not widely reported. These findings cast doubt on the impact of many of the most common mitigation measures in American schools. Distancing, hybrid models, classroom barriers, HEPA filters, and, most notably, requiring student masking were each found to not have a statistically significant benefit. In other words, these measures could not be said to be effective. -NYMag
According to the report, scientists believe that the CDC’s decision to intentionally omit the findings on student masking from a summary of the study amounts to “file drawering” the findings – the practice of burying studies that don’t have statistically significant results.