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Observational Study
. 2022 Apr 27:377:e069317.
doi: 10.1136/bmj-2021-069317.

Public health impact of covid-19 vaccines in the US: observational study

Amitabh Bipin Suthar  1 , Jing Wang  2 , Victoria Seffren  2 , Ryan E Wiegand  2 , Sean Griffing  2 , Elizabeth Zell  2
Affiliations
Observational Study

Public health impact of covid-19 vaccines in the US: observational study

Amitabh Bipin Suthar et al. BMJ. .

Abstract

Objective: To evaluate the impact of vaccine scale-up on population level covid-19 mortality and incidence in the United States.

Design: Observational study.

Setting: US county level case surveillance and vaccine administration data reported from 14 December 2020 to 18 December 2021.

Participants: Residents of 2558 counties from 48 US states.

Main outcome measures: The primary outcome was county covid-19 mortality rates (deaths/100 000 population/county week). The secondary outcome was incidence of covid-19 (cases/100 000 population/county week). Incidence rate ratios were used to compare rates across vaccination coverage levels. The impact of a 10% improvement in county vaccination coverage (defined as at least one dose of a covid-19 vaccine among adults ≥18 years of age) was estimated During the eras of alpha and delta variant predominance, the impact of very low (0-9%), low (10-39%), medium (40-69%), and high (≥70%) vaccination coverage levels was compared.

Results: In total, 30 643 878 cases of covid-19 and 439 682 deaths associated with covid-19 occurred over 132 791 county weeks. A 10% improvement in vaccination coverage was associated with an 8% (95% confidence interval 8% to 9%) reduction in mortality rates and a 7% (6% to 8%) reduction in incidence. Higher vaccination coverage levels were associated with reduced mortality and incidence rates during the eras of alpha and delta variant predominance.

Conclusions: Higher vaccination coverage was associated with lower rates of population level covid-19 mortality and incidence in the US.

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Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/disclosure-of-interest/ and declare: no support from any organization for the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

Figures

Fig 1
Fig 1
County scale-up of vaccinations from 13 December 2020 to 18 December 2021. Light purple lines represent individual counties; dark purple line is aggregated estimate
Fig 2
Fig 2
Effect of vaccination coverage on county covid-19 related mortality (top) and incidence (bottom) during first year of vaccine roll-out. Analyses are from 2558 counties in 48 US jurisdictions. Model controlled for county population size, social vulnerability index, and mobility changes
Fig 3
Fig 3
Effect of vaccination coverage on county covid-19 mortality and incidence during era of alpha variant predominance. Analyses are from 2557 counties in 48 US jurisdictions. Model controlled for county population size, social vulnerability index, and mobility changes
Fig 4
Fig 4
Sensitivity analyses of including only fully vaccinated people, increasing data stringency requirements, and removing two week immunity lag period. *In baseline group, vaccination coverage refers to coverage of at least one dose of vaccine, 2558 counties and 48 US jurisdictions included had ≥70% completeness rates of reporting county of residence, and study period was 14 December 2020 to 18 December 2021. †Vaccination coverage refers to coverage of fully vaccinated people. ‡2164 counties and 42 US jurisdictions included had ≥90% completeness rates of reporting county of residence. §Two week immunity period was removed
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References

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Supplementary concepts