The interplay between vaccination and social distancing strategies affects COVID19 population-level outcomes

PLoS Comput Biol. 2021 Aug 20;17(8):e1009319. doi: 10.1371/journal.pcbi.1009319. eCollection 2021 Aug.

Abstract

Social distancing is an effective population-level mitigation strategy to prevent COVID19 propagation but it does not reduce the number of susceptible individuals and bears severe social consequences-a dire situation that can be overcome with the recently developed vaccines. Although a combination of these interventions should provide greater benefits than their isolated deployment, a mechanistic understanding of the interplay between them is missing. To tackle this challenge we developed an age-structured deterministic model in which vaccines are deployed during the pandemic to individuals who do not show symptoms. The model allows for flexible and dynamic prioritization strategies with shifts between target groups. We find a strong interaction between social distancing and vaccination in their effect on the proportion of hospitalizations. In particular, prioritizing vaccines to elderly (60+) before adults (20-59) is more effective when social distancing is applied to adults or uniformly. In addition, the temporal reproductive number Rt is only affected by vaccines when deployed at sufficiently high rates and in tandem with social distancing. Finally, the same reduction in hospitalization can be achieved via different combination of strategies, giving decision makers flexibility in choosing public health policies. Our study provides insights into the factors that affect vaccination success and provides methodology to test different intervention strategies in a way that will align with ethical guidelines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • COVID-19 / prevention & control*
  • COVID-19 / virology
  • COVID-19 Vaccines / administration & dosage*
  • Hospitalization
  • Humans
  • Physical Distancing*
  • SARS-CoV-2 / isolation & purification

Substances

  • COVID-19 Vaccines

Grants and funding

This research was supported by the Israel Ministry of Science and Technology (grant no. 3-16893 to SP, RP and ND). https://www.gov.il/en/departments/ministry_of_science_and_technology. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.