At least one million coronavirus infections and over 59,000 deaths may have been prevented in the United States in May had social distancing, business closures, and other non-pharmaceutical interventions been implemented two weeks sooner, a study published in the Science Advances journal said.
The results highlight the importance of quick and aggressive non-pharmaceutical interventions implementation to counter transmission of the SARS-CoV-2 virus and could help inform efforts to control new surges in the US and elsewhere in the world.
“Our results demonstrate the dramatic impact that earlier interventions could have had on the COVID-19 pandemic in the US,” the authors wrote.
Seeking to understand the impact of timing when implementing non-pharmaceutical interventions, Sen Pei from Columbia University in New York and colleagues first built a metapopulation model of Covid-19 transmission in all 3,142 US counties during the period spanning February 21 through May 3.
They built the model using county-level data of confirmed cases and deaths.
The model revealed notable yet asynchronous reductions in disease transmission rates, reflected in changes to the estimated effective basic reproduction number (Re) in most counties during this time period.
They then performed counterfactual simulations with the same model, moving the timing of non-pharmaceutical interventions implementation either one week or two weeks sooner.
In the first model, advancing non-pharmaceutical interventions by a week, to March 8, resulted in 601,667 fewer confirmed cases and 32,335 fewer deaths nationwide as of May 3.
In the second model, implementing NPIs a full two weeks earlier, on March 1, resulted in over one million fewer confirmed cases and 59,351 fewer deaths.
The researchers acknowledged that their modeling simplifies some assumptions related to general uncertainty, economic concerns, administrative decision-making, and public adherence to social distancing rules.
However, they also pointed to continuing successes in countries such as South Korea, New Zealand, Vietnam, and Iceland that did implement non-pharmaceutical interventions in early March.