SARS-CoV-2 aerosol transmission in schools: the effectiveness of different interventions
This article has been Reviewed by the following groups
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- Evaluated articles (ScreenIT)
- Evaluated articles (Rapid Reviews Infectious Diseases)
Abstract
Background
Indoor aerosol transmission of SARS-CoV-2 has been widely recognized, especially in schools where children remain in closed indoor spaces and largely unvaccinated. Measures such as strategic natural ventilation and high efficiency particulate air (HEPA) filtration remain poorly implemented and mask mandates are often progressively lifted as vaccination rollout is enhanced.
Methods
We adapted a previously developed aerosol transmission model to study the effect of interventions (natural ventilation, face masks, HEPA filtration, and their combinations) on the concentration of virus particles in a classroom of 160 m 3 containing one infectious individual. The cumulative dose of viruses absorbed by exposed occupants was calculated.
Results
The most effective single intervention was natural ventilation through the full opening of six windows all day during the winter (14-fold decrease in cumulative dose), followed by the universal use of surgical face masks (8-fold decrease). In the spring/summer, natural ventilation was only effective (≥ 2-fold decrease) when windows were fully open all day. In the winter, partly opening two windows all day or fully opening six windows at the end of each class was effective as well (≥ 2-fold decrease). Opening windows during yard and lunch breaks only had minimal effect (≤ 1.2-fold decrease). One HEPA filter was as effective as two windows partly open all day during the winter (2.5-fold decrease) while two filters were more effective (4-fold decrease). Combined interventions (i.e., natural ventilation, masks, and HEPA filtration) were the most effective (≥ 30-fold decrease). Combined interventions remained highly effective in the presence of a super-spreader.
Conclusions
Natural ventilation, face masks, and HEPA filtration are effective interventions to reduce SARS-CoV-2 aerosol transmission. These measures should be combined and complemented by additional interventions (e.g., physical distancing, hygiene, testing, contact tracing, and vaccination) to maximize benefit.
Article activity feed
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Brian Pavilonis
Review 3: "SARS-CoV-2 Aerosol Transmission in Schools: The Effectiveness of Different Interventions"
Reviewers find this a straightforward modelling study, though ask for clarification on some assumptions and emphasize that the results may apply only to naturally-ventilated classrooms.
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Richard M. Lynch, Ph.D.
Review 2: "SARS-CoV-2 Aerosol Transmission in Schools: The Effectiveness of Different Interventions"
Reviewers find this a straightforward modelling study, though ask for clarification on some assumptions and emphasize that the results may apply only to naturally-ventilated classrooms.
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Jacob Bueno de Mesquita
Review 1: "SARS-CoV-2 Aerosol Transmission in Schools: The Effectiveness of Different Interventions"
Reviewers find this a straightforward modelling study, though ask for clarification on some assumptions and emphasize that the results may apply only to naturally-ventilated classrooms.
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Strength of evidence
Reviewers: Jacob Bueno de Mesquita, Ph.D (UC Berkeley) | 📗📗📗📗◻️
Richard M. Lynch, Ph.D (Preferred Management Corporation) | 📗📗📗📗◻️
Brian Pavilonis (CUNY School of Public Health) | 📒📒📒 ◻️◻️ -
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SciScore for 10.1101/2021.08.17.21262169: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:One important limitation of our model comes from the lack of consensus regarding the infectious dose. Hence, we cannot predict, on a quantitative level, what measures are sufficient to keep the occupants of the room safe. Nonetheless, reducing the number of inhaled virions will result in an exponential reduction in the probability of …
SciScore for 10.1101/2021.08.17.21262169: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:One important limitation of our model comes from the lack of consensus regarding the infectious dose. Hence, we cannot predict, on a quantitative level, what measures are sufficient to keep the occupants of the room safe. Nonetheless, reducing the number of inhaled virions will result in an exponential reduction in the probability of contracting the disease. Therefore, we can estimate the mean cumulative dose absorbed in each scenario and by how much it varies based on the interventions implemented. Furthermore, the infectious dose is hypothesized to vary depending on the SARS-CoV-2 variant. Since no significant change in viral load has been observed between the original variant and the alpha variant,39 the most likely hypothesis to explain the increased infectivity of the alpha variant is a genetic mutation in the spike protein enabling it to more effectively bind to the ACE2 receptor,40 thereby decreasing the amount of viral particles needed to infect a susceptible host. With the rise of the delta variant, which became dominant in England within months8 and is rapidly spreading across many countries, we can expect the infectious dose to decrease, making new outbreaks more difficult to contain. For example, in Bolton, UK, where the delta variant became first dominant, data suggested that the infection first spread among school-age children.41 The delta variant has already been identified in 195 outbreaks or clusters in primary and secondary schools in England from April 26 t...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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