A team of researchers from the United States (US) and Canada analyzed the impact of accelerating the pace of coronavirus disease 2019 (COVID-19) booster vaccination rates in the US in reducing COVID-19-related hospitalizations and mortalities.

The study is currently available on the medrxiv* preprint server, before it undergoes peer review.

Study: Impact of accelerating booster vaccination amidst Omicron surge in the United States. Image Credit: Halfpoint/ShutterstockStudy: Impact of accelerating booster vaccination amidst Omicron surge in the United States. Image Credit: Halfpoint/Shutterstock


The explosive spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) along with the emerging SARS-CoV-2 Delta and Omicron variants of concern is causing over a million new cases daily in the US posing a threat to the health care system.

With the emergence of new variants combined with waning immunity, there is a dire need for an immediate and aggressive increase in the daily pace of the booster vaccination program to flatten the curve of SARS-CoV-2-related-infections and morbidity.

About the study

In this study, the researchers used an age-stratified, multi-variant agent-based model of coronavirus disease 2019 (COVID-19) transmission. The simulation of the pandemic trajectory from January 1 to April 30, 2022, was conducted by fitting the model to observed incidences through December 29, 2021.

Forecasts of the pace of booster vaccination in the US were compared to scenarios of accelerated booster vaccination that double and triple the rate of booster administration.


The results showed that the current booster vaccination rate of approximately 770,000 doses per day in the US would lead to approximately 110 million infections, 17,14,329 hospitalizations, and 2,18,488 deaths. On contrary, doubling the rate of booster vaccination to the tone of 1.5 million doses per day would prevent 401897 hospitalizations and 48,358 (95% credible interval (CrI): 40,279 to 56,987) mortalities. Tripling the booster vaccination rate to 2.3 million doses per day would avert 6,19,133 (5,76,113 to 6,63,140) hospitalizations and save 70,603 (95% CrI: 61,658 to 79,642) lives as compared to the current scenario.

The researchers projected that at the current pace of booster vaccination, daily counts of COVID-19-related hospital admissions would peak at approximately 30,000 by the end of January 2022, exceeding 20,000 hospitalizations a day for up to six weeks. Doubling the pace of booster vaccination will cause a reduction in peak to 25,000 per day while tripling the booster vaccination rate for less than 3 weeks will further curtail the peak to approximately 21,000 new admissions daily.

The impact of accelerating the rate of booster vaccination was remarkable in reducing COVID-19-related hospitalizations in adult populations, especially in the age group of 80 years and above.


The current study results demonstrated the potential of accelerating the US booster vaccination program over the coming several months in reducing the workload on already overburdened hospitals and healthcare workers.

Booster vaccination will curtail the severity of infection and loss of lives due to the current Omicron variant. The US booster vaccination program will not only be effective in mitigating the current surge of SARS-CoV-2 infections but will bolster otherwise waning population immunity and may protect the population against newly emerging variants in the future.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.


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