Do social distancing & wearing face marks help?

People have expressed to me that they are not certain if the wearing of face masks, and/or social distancing is of any real benefit in terms of limiting the impact of Covid-19 disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To help others reach informed ideas, I examined two of many research-based articles that provide evidence that such non-pharmaceutical interventions (NPIs) do have a beneficial impact.

Is face mask wearing worthwhile?

The first study compared the influence of two different policies in eight states within the US. One policy was that the entire state was mandated to wear face masks or covers, and the other policy was that the wearing of masks was either not required or only partially required. States in the first group included New York, Pennsylvania, Connecticut, and New Jersey, while states in the second group included Florida, California, and Texas. The period that was assessed was between 1 March 2020 and 15 June 2020. They used the number of confirmed cases of the virus as their yardstick, that is as their measured outcome.

The authors of the study also wanted to determine the approximated number of deaths due to Covid-19 that could have been prevented if all state governments imposed mandatory face mask wearing in public.

Their abstract state that:

it was very encouraging that the slope of the daily case trends turned negative [that is the rate of people being infected reduced] after face‐cover requirements [were introduced] in statewide face‐cover‐required states, including New York, New Jersey, Pennsylvania, and Connecticut. However, the patterns of the daily case [numbers] have been showing positive trends [that is the rate of people being infected increased] continuously in … [the other states].

In other words, if an entire state insisted on the wearing of face masks, then this resulted in significant benefits compared to if only some or none of a state imposed this requirement.

Elsewhere in their paper the authors estimated that

Approximately 36,300 lives could have been saved if the federal or all state governments had enacted mandatory face‐cover requirements in mid‐April [2020].

Reference: H Kim et al., Predictive Analyses of COVID-19 Case Data to Estimate the Effectiveness of Nationwide Face Cover, World Med Health Policy 2021 Feb 17;10.1002/wmh3.399. doi: 10.1002/wmh3.399.

Is social distancing worthwhile?

The second study examined the effect of implementing social distancing (also called spatial distancing or societal lockdown) on the spread of the virus. The types of social distancing included

a combination of travel restrictions, closure of non-essential group meeting venues (e.g., restaurants, schools, shops) and steps to avoid close contact at essential meeting venues (e.g., hospitals, food supply, pharmacies).

This large study extracted their evidence from Covid-19 cases from nearly 120 geographic areas in over 41 states within the US, as we all dated from 78 other countries. The main measurement of outcome that they used was

The highest number of new COVID-19 cases per day recorded within a geographic unit was the primary outcome.

To do this study they only examined those

regions that had data for both mandated social distancing start dates and daily cumulative case volumes for COVID-19 were included. For the United States, data were available for each state, thus allowing a detailed analysis. In countries other than the United States, we used national mandated social distancing start dates and national COVID-19 case volumes.

They stated that the results suggest that

if mandated social distancing is not initiated until the number of existing COVID-19 cases has doubled, the eventual peak [of people being infected] would result in 58% more COVID-19 cases per day.

They concluded that

Initiating mandated social distancing when the numbers of COVID-19 cases are low within a region significantly reduces the number of new daily COVID-19 cases and perhaps also reduces the total number of cases in the region.

It seems that social distancing can be a very helpful tool in mitigating the numbers of people that will be infected with SARS-CoV-2, especially if it is introduced early in an outbreak.

Reference: AI Qureshi et al., Early mandated social distancing is a strong predictor of reduction in peak daily new COVID-19 cases, Public Health. 2021 Jan; 190: 160–167. Published online 2020 Oct 21. doi: 10.1016/j.puhe.2020.10.015

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