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. 2021 Jun 1;4(6):e2110782.
doi: 10.1001/jamanetworkopen.2021.10782.

Association of Simulated COVID-19 Vaccination and Nonpharmaceutical Interventions With Infections, Hospitalizations, and Mortality

Mehul D Patel  1 , Erik Rosenstrom  2 , Julie S Ivy  2 , Maria E Mayorga  2 , Pinar Keskinocak  3 , Ross M Boyce  4 , Kristen Hassmiller Lich  5 , Raymond L Smith 3rd  6 , Karl T Johnson  5 , Paul L Delamater  7 , Julie L Swann  2
Affiliations

Association of Simulated COVID-19 Vaccination and Nonpharmaceutical Interventions With Infections, Hospitalizations, and Mortality

Mehul D Patel et al. JAMA Netw Open. .

Abstract

Importance: Vaccination against SARS-CoV-2 has the potential to significantly reduce transmission and COVID-19 morbidity and mortality. The relative importance of vaccination strategies and nonpharmaceutical interventions (NPIs) is not well understood.

Objective: To assess the association of simulated COVID-19 vaccine efficacy and coverage scenarios with and without NPIs with infections, hospitalizations, and deaths.

Design, setting, and participants: An established agent-based decision analytical model was used to simulate COVID-19 transmission and progression from March 24, 2020, to September 23, 2021. The model simulated COVID-19 spread in North Carolina, a US state of 10.5 million people. A network of 1 017 720 agents was constructed from US Census data to represent the statewide population.

Exposures: Scenarios of vaccine efficacy (50% and 90%), vaccine coverage (25%, 50%, and 75% at the end of a 6-month distribution period), and NPIs (reduced mobility, school closings, and use of face masks) maintained and removed during vaccine distribution.

Main outcomes and measures: Risks of infection from the start of vaccine distribution and risk differences comparing scenarios. Outcome means and SDs were calculated across replications.

Results: In the worst-case vaccination scenario (50% efficacy, 25% coverage), a mean (SD) of 2 231 134 (117 867) new infections occurred after vaccination began with NPIs removed, and a mean (SD) of 799 949 (60 279) new infections occurred with NPIs maintained during 11 months. In contrast, in the best-case scenario (90% efficacy, 75% coverage), a mean (SD) of 527 409 (40 637) new infections occurred with NPIs removed and a mean (SD) of 450 575 (32 716) new infections occurred with NPIs maintained. With NPIs removed, lower efficacy (50%) and higher coverage (75%) reduced infection risk by a greater magnitude than higher efficacy (90%) and lower coverage (25%) compared with the worst-case scenario (mean [SD] absolute risk reduction, 13% [1%] and 8% [1%], respectively).

Conclusions and relevance: Simulation outcomes suggest that removing NPIs while vaccines are distributed may result in substantial increases in infections, hospitalizations, and deaths. Furthermore, as NPIs are removed, higher vaccination coverage with less efficacious vaccines can contribute to a larger reduction in risk of SARS-CoV-2 infection compared with more efficacious vaccines at lower coverage. These findings highlight the need for well-resourced and coordinated efforts to achieve high vaccine coverage and continued adherence to NPIs before many prepandemic activities can be resumed.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Patel reported receiving grants from the National Center for Advancing Translational Sciences (NCATS) of the National Institutes of Health (NIH) and from the Council of State and Territorial Epidemiologists (CSTE) during the conduct of the study. Mr Rosenstrom reported receiving grants from the Centers for Disease Control and Prevention (CDC) and Translational and Clinical Sciences during the conduct of the study. Dr Ivy reported receiving grants from the CSTE and CDC-Prime and a University of North Carolina/North Carolina State Translational Research Grant during the conduct of the study. Dr Mayorga reported receiving grants from the NCATS/NIH, CSTE, and CDC during the conduct of the study. Dr Swann reported receiving grants from the Department of Health and Human Services, NCATS/NIH, and CSTE during the conduct of the study. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Description of Vaccination and Nonpharmaceutical Interventions (NPIs) During the 18-Month Simulation
The agent-based model simulated an 18-month period, with vaccines distributed during 6 months and NPIs implemented. Midway through vaccine distribution, NPIs were either maintained or removed. Outcomes were computed across the entire simulation and from the start of vaccination to the end of the simulation.
Figure 2.
Figure 2.. Daily New Infections by Vaccination and Nonpharmaceutical Intervention (NPI) Scenarios During the 18-Month Simulation
Modeled new infections by day are shown across varying vaccine efficacy and coverage with NPIs maintained and removed.
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