Coronavirus Disease 2019 (COVID-19) Transmission in the United States Before Versus After Relaxation of Statewide Social Distancing Measures

Abstract

Background Weeks after issuing social distancing orders to suppress severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and reduce growth in cases of severe coronavirus disease 2019 (COVID-19), all U.S. states and the District of Columbia partially or fully relaxed these measures. Methods We identified all statewide social distancing measures that were implemented and/or relaxed in the U.S. between March 10-July 15, 2020, triangulating data from state government and third-party sources. Using segmented linear regression, we estimated the extent to which relaxation of social distancing affected epidemic control, as indicated by the time-varying, state-specific effective reproduction number (Rt). Results In the eight weeks prior to relaxation, mean Rt declined by 0.012 units per day (95% CI, -0.013 to -0.012), and 46/51 jurisdictions achieved Rt < 1.0 by the date of relaxation. After relaxation of social distancing, Rt reversed course and began increasing by 0.007 units per day (95% CI, 0.006-0.007), reaching a mean Rt of 1.16 eight weeks later, with only 9/51 jurisdictions maintaining Rt <1.0. Parallel models showed similar reversals in the growth of COVID-19 cases and deaths. Indicators often used to motivate relaxation at the time of relaxation (e.g. test positivity rate <5%) predicted greater post-relaxation epidemic growth. Conclusions We detected an immediate and significant reversal in SARS-CoV-2 epidemic suppression after relaxation of social distancing measures across the U.S. Premature relaxation of social distancing measures undermined the country’s ability to control the disease burden associated with COVID-19.

Trends in SARS-CoV-2 detection during social relaxation measures over ten months of COVID-19 pandemic in the metropolitan area of Rio de Janeiro, Brazil

“…In contrast to different authors ( 1,3,4,11 ), our data showed that most social relaxing events including the opening of bars and restaurants, gyms, beauty salons, shopping centers, transportation, among others (EW 20 to 41), had a limited effect on SARS-CoV-2 cases. Although it was possible to observe an increase in cases after some of the opening events, our results indicate that such measures had a temporary and not a cumulative effect, which was also reflected in the stability of reported deaths, the most important and stable outcome, not subject to testing variations, testing policy and infrastructure ( 8 ).…”

“…Several authors have assessed the impact of social relaxation events in the COVID-19 pandemic before vaccination was implemented. In general, the proposed analyzes are based on projections by epidemiological models ( 1,2 ), shorter follow-up periods ( 3 ), or using data from government databases ( 4 ). Such information is crucial, providing projections on the pandemic in different scenarios.…”

Association of social distancing and masking with risk of COVID-19

“…Our findings are consistent with previous ecological studies investigating the effect of social distancing on risk of COVID-19 [21][22][23][24][25][26][27][28] . In one recent study that also used estimates of social distancing based on Unacast data, each one-unit increase in social distancing was associated with a 29% reduced risk of COVID-19 incidence and a 35% reduced risk of COVID-19 mortality 22 at the county-level.…”

High anti-SARS-CoV-2 antibody seroconversion rates before the second wave in Manaus, Brazil, and the protective effect of social behavior measures: Results from the DETECTCoV-19 cohort.

“…Therefore, lifting NPI abruptly diminishes the gains accumulated by previously implemented policies 7,13 . In our study, individuals who relaxed social distancing measures 14 or had contact with COVID-19 individuals without mask 15,16 had the highest risk of acquiring SARS-CoV-2 infection.…”