Consistent Mask Use and the Epidemiology of SARS-CoV-2: A Simulation Modeling Study

Masks effectively reduce transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).1 However, the impact of long-term mask wearing on population-level morbidity and mortality is less clear, especially given the interplay between mask effectiveness, herd immunity, and other public health and social measures. .

We recently evaluated the costs and benefits of over 100 coronavirus disease 2019 (COVID-19) control policies used in Victoria combined with nine scenarios for SARS-CoV-integrated epidemiological and economic factors. We reported the results of the base model. Two subspecies appeared in 18 months from April 2022.2 We included mask interventions implemented only during large epidemic waves when both general mask wearing and the proportion of mask wearing, including respirators (e.g., N95 masks), increase. These policies have minimized health impacts.2 This study extends these analyses, to show that consistent mask wearing (i.e., outside the home at all times) at the regional level by age group is associated with fewer SARS-CoV-2 infections and COVID-19-related deaths. We determined the effect on the number of participants.

We modeled different levels of consistent mask wearing by people under the age of 60 (none, 20%, 35%, 50%; lower percentages were applied to people under 20. see footnote) box 1) with equal or greater mask wearing by people over 60 (about 20% of the population),3 Up to 75%. At each level of use, it was assumed that his 80% of the masks used were cloth or surgical masks and 20% were respirators. Other public health and social measures have been modified. The model will begin in April 2022 with Omicron BA.1 and BA.2 as the primary SARS-CoV-2 variants, and from May 2022 he will gradually expand to BA.4 and BA.5. Appeared in We calculated the median quarterly and cumulative number of cases. Number of deaths in 12 months from April 2022 (500 model runs for each scenario, accounting for stochastic and input parameter uncertainties) Number of people exposed to infected persons (wearing masks) Odds ratio for relative risk of infection v mask not worn), was set to 0.47 for cloth and surgical masks, and 0.20 for respirators.1 (Model details: Support information, Supplementary Methods). We used publicly available data and did not seek formal ethical approval for the study.

Consistently 20% mask use across both age groups (under 60, over 60) compared to no mask wearing reduced the median number of infections by 16.4% (uncertainty section) [UI; 5th to 95th percentiles], -30.4% to +2.7%), and median deaths increased by 10.6% (UI, -33.0% to +20.7%). Increasing mask-wearing rates to 50% for both age groups reduced the number of infections by 38.4% (UI, -96.0% to -6.7%) and the number of deaths by 25.8% (UI, -97.0% to +26.1%). bottom. The effect of any level of mask wearing by people under 60 was not significantly affected by the level of mask wearing in people over 60 (box 1). The largest reduction in cases and deaths achieved was in the first quarter of the model period (box 2). The increase in deaths in the third quarter may be related to the decline in infection-derived immunity associated with the decline in viral infection early in the model run. However, in these scenarios, cumulative infections and deaths were still lower than with zero mask wearing. The impact of mask wearing on COVID-19-related hospitalizations was similar to that on infections and deaths (Support informationTable 5).

Our model identifies that older people have less contact with others, but we do not identify the probability of contact with people of a particular age group, so we recommend mask use especially for those over 60. We may have underestimated the protective effect of increasing it on older people. Moreover, the uncertainty range of the modeled output is very wide. This is a result of uncertainty in the input parameters, such as estimating the effectiveness of the mask (Support information, Supplementary Methods), stochastic uncertainty (only 5000 agents were included in the model). Finally, our mask efficacy estimate is based on the results of a single study.1 The literature on the effectiveness of masks is very diverse,Four And this topic needs further high-quality research.

The ultimate impact of mask-wearing will depend on the level of other interventions, such as vaccination coverage. Nonetheless, our findings suggest that consistently high mask-wearing rates across all age groups would reduce the cumulative infection and mortality burden in Victoria.

Box 2 – Quarterly cases and deaths modeling for Victoria from April 2022 to March 2023 (based on 500 model runs with independent extraction of input parameters), under 60 and people over 60 by level of mask wearing*

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