Non-pharmaceutical interventions to contain COVID-19

While the availability of COVID-19 vaccines has increased since their approval in the United States in late 2020, non-pharmaceutical interventions remain crucial to containing the spread of COVID-19 and keeping economic interests in mind. Ideally, a successful non-pharmaceutical intervention reduces both disease transmission and economic loss. Understanding how well masks stop the spread of COVID-19, for instance, gives an idea of how many businesses can safely open. Finally, successful non-pharmaceutical interventions are not only relevant to COVID-19: future infectious disease outbreaks will rely on the prior success of these interventions. In order to answer these questions, the researchers used epidemiological and mobility data to analyze the effectiveness of mask-wearing and social distancing measures on COVID-19 transmission reduction during the spring 2020 New York City pandemic wave.

In March 2020, New York City implemented a series of measures to stop the spread of COVID-19 in light of widespread transmission and climbing deaths: public schools closed, “non-essential” workers were asked to stay home, and by April, the public was asked to wear face coverings. In the weeks that followed these measures, cases and hospitalizations declined significantly. However, it has been difficult to assess the effectiveness of any given measure implemented during this time, because of real-world low infection detection rates (due to individuals with no or mild symptoms), age group stratification, and concurrent interventions during spring 2020. Accounting for these factors, the authors developed a model incorporating COVID-19 cases, deaths, and neighborhood-level mobility data in order to gauge the effectiveness of different COVID-19 interventions.

Yang and coauthors found that reducing contact between individuals, through school closures and staying at home, contributed to around 70% reduced COVID-19 transmission in the population overall during the 2020 spring pandemic wave. Furthermore, the authors found that widespread mask wearing contributed to an added 7% reduction overall and up to a 20% reduction among 65+ year-olds in April 2020. These findings indicate that wearing masks can reduce transmission, but alone may be insufficient without social distancing measures also in place. The authors also note that future interventions should take into account the fact that not all populations have been able to physically distance, and that in NYC, these disparities have been largely present among Black and Latino residents, who make up a significant portion of essential workers. These findings assess two major interventions for widespread disease such as COVID-19 and can therefore inform future public health needs.

Yang W, Shaff J, Shaman J. Effectiveness of non-pharmaceutical interventions to contain COVID-19: a case study of the 2020 spring pandemic wave in New York City. J. R. Soc. Interface. 2021 February;18(175). https://doi.org/10.1098/rsif.2020.0822