The vaccination threshold for SARS-CoV-2 depends on the indoor setting and room ventilation
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Abstract
Background
Effective vaccines are now available for SARS-CoV-2 in the 2nd year of the COVID-19 pandemic, but there remains significant uncertainty surrounding the necessary vaccination rate to safely lift occupancy controls in public buildings and return to pre-pandemic norms. The aim of this paper is to estimate setting-specific vaccination thresholds for SARS-CoV-2 to prevent sustained community transmission using classical principles of airborne contagion modeling. We calculated the airborne infection risk in three settings, a classroom, prison cell block, and restaurant, at typical ventilation rates, and then the expected number of infections resulting from this risk at varying percentages of occupant immunity.
Results
We estimate the setting-specific immunity threshold for control of wild-type SARS-CoV-2 to range from a low of 40% for a mechanically ventilation classroom to a high of 85% for a naturally ventilated restaurant.
Conclusions
If vaccination rates are limited to a theoretical minimum of approximately two-thirds of the population, enhanced ventilation above minimum standards for acceptable air quality is needed to reduce the frequency and severity of SARS-CoV-2 superspreading events in high-risk indoor environments.
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SciScore for 10.1101/2021.07.28.21261300: (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:A limitation of our infection risk modeling approach is the assumption of a homogeneous concentration of droplet nuclei within the room, with viral emissions being instantaneously and completely mixed. However, a recent comparison of this box-modeling approach with computational fluid dynamics (CFD) simulations for a classroom …
SciScore for 10.1101/2021.07.28.21261300: (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:A limitation of our infection risk modeling approach is the assumption of a homogeneous concentration of droplet nuclei within the room, with viral emissions being instantaneously and completely mixed. However, a recent comparison of this box-modeling approach with computational fluid dynamics (CFD) simulations for a classroom environment indicates relatively minor errors for natural (6%) and forced mechanical (29%) ventilation scenarios [27]. The uncertainty in the emission rate, based on viral loads that vary several orders of magnitude between individuals and over time [28], is likely much more significant than that caused by incomplete mixing at the small scale of our models. Further improvements to the emission rate distributions are needed that incorporate variation in droplet volume concentrations [28, 29], such that a more complete stochastic emission model can be implemented. An additional limitation is our estimation of vaccination thresholds using singular, setting-specific events, without considering cumulative exposure effects that may result from an infectious person attending class in two successive days, for example. The importance of singular SSEs on SARS-CoV-2 transmission is well established, and such events likely occur during a narrow 1-2 day window of peak infectivity [30]. As such we do not expect cumulative exposures to be a significant factor outside of co-habitation environments, which is why our prison scenario used a 36-hour duration. Our approach ...
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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