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SYSTEMATIC REVIEW article

Front. Public Health
Sec. Infectious Diseases: Epidemiology and Prevention
Volume 12 - 2024 | doi: 10.3389/fpubh.2024.1426992

Effects of Non-Pharmaceutical Interventions on COVID-19 Transmission: Review of Evidence from Italy, the United States, the United Kingdom, and China

Provisionally accepted
Laura J. Faherty Laura J. Faherty 1,2,3*Pedro Nascimento de Lima Pedro Nascimento de Lima 1Jing Zhi Lim Jing Zhi Lim 1Derek Roberts Derek Roberts 1Sarah Karr Sarah Karr 1Emily Lawson Emily Lawson 1Henry Willis Henry Willis 4
  • 1 RAND Corporation, Santa Monica, United States
  • 2 Maine Medical Center, Maine Health, Portland, Maine, United States
  • 3 School of Medicine, Tufts University, Boston, Massachusetts, United States
  • 4 RAND Corporation, Pittsburgh, United States

The final, formatted version of the article will be published soon.

    Background: Prior to the development of COVID-19 vaccines, policymakers instituted various nonpharmaceutical interventions (NPIs) to limit transmission. Prior studies have attempted to examine the extent to which these NPIs achieved their goals of containment, suppression, or mitigation of disease transmission. Existing evidence syntheses have found that numerous factors limit comparability across studies, and the evidence on NPI effectiveness during COVID-19 pandemic remains sparse and inconsistent. This study documents the magnitude and variation in NPI effectiveness in reducing COVID-19 transmission (i.e., reduction in effective reproduction rate [Reff] and daily contact rate) in Italy, the United States, the United Kingdom, and China. Methods: Our rapid review and narrative synthesis of existing research identified 126 studies meeting our screening criteria. We selected four contexts with >5 articles to facilitate a meaningful synthesis. This step yielded an analytic sample of 61 articles that used data from China, Italy, the United Kingdom, and the United States.Results: We found wide variation and substantial uncertainty around the effectiveness of NPIs at reducing disease transmission. Studies of a single intervention or NPIs that are the least stringent had estimated Reff reductions in the 10-50% range; those that examined so-called "lockdowns" were associated with greater Reff reductions that ranged from 40-90%, with many in the 70-80% range. While many studies reported on multiple NPIs, only six of the 61 studies explicitly used the framing of "stringency" or "mild versus strict" or "tiers" of NPIs, concepts that are highly relevant for decisionmakers.Conclusions: Existing evidence suggests that NPIs reduce COVID-19 transmission by 40 to 90 percent. This paper documents the extent of the variation in NPI effectiveness estimates and highlights challenges presented by a lack of standardization in modeling approaches. Further research on NPI effectiveness at different stringency levels is needed to inform policy responses to future pandemics.

    Keywords: COVID-19, Non-pharmaceutical interventions, Effective reproduction number, Contact rate, Disease transmission, infectious disease modeling Article Information Context NPI(s) Examined Study Type Key Findings

    Received: 02 May 2024; Accepted: 01 Oct 2024.

    Copyright: © 2024 Faherty, Nascimento de Lima, Lim, Roberts, Karr, Lawson and Willis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Laura J. Faherty, RAND Corporation, Santa Monica, United States

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.