2022 Yes https://onlinelibrary.wiley.com/doi/10.1111/ina.13142 McLeod, Robert S. North America Europe Review Teachers Staff Students Elementary (K-5) Middle/Jr High (6-8) High School (9-12) Air purification infection prophylaxis in school classrooms Masking and physical distancing Mechanical ventilation natural ventilation. This review provides a comprehensive synthesis of current scientific evidence and emerging standards in relation to the use of layered prevention strategies (involving masks, distancing, and ventilation), setting out the basis for their implementation in the school environment. In the presence of increasingly infectious SARS-Cov-2 variants, in-classroom teaching can only be safely maintained through a layered strategy combining multiple protective measures. The precise measures that are needed at any point in time depend upon a number of dynamic factors, including the specific threat-level posed by the circulating variant, the level of community infection, and the political acceptability of the resultant risk. By consistently implementing appropriate prophylaxis measures, evidence shows that the risk of infection from in-classroom teaching can be dramatically reduced.