Prioritization of Primary Versus Booster Vaccinations for the Prevention of COVID-19 Incidence and Hospitalization Open Access

Krupinsky, Kathryn (Spring 2022)

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Background. Since their introduction at the end of 2020, COVID-19 vaccines have been instrumental tools in combating the pandemic. A year after becoming available to the general population, the proportion of the United States population that received primary and booster vaccinations remains low despite their high effectiveness. Given the limited public health resources for increasing vaccine uptake, there is a present need to determine whether more attention should be given to increasing the number of individuals who receive their primary vaccination series versus increasing the number of primary-vaccinated individuals who receive a booster vaccination dose.

Methods. For this study, we built upon a network-based mathematical model to include booster vaccination, waning immunity, multiple SARS-CoV-2 strains, and reinfection. This model was designed to represent the local epidemic in the state of Georgia, USA from approximately January 2021–December 2021 and was parameterized using published literature and Georgia Department of Public Health surveillance data. Multiple scenarios were run with higher and lower rates of primary and booster vaccine administration. Total incidence, symptomatic infections, and hospitalizations were recorded for the general and greater than 65 population.

Results. We found that increasing the rate of both primary and booster vaccination doses decreased the infection and hospitalization rates in both the general and greater than 65 population. However, the booster vaccination dose had a smaller impact on these rates compared to rates of primary vaccination. Sensitivity analysis showed that this minimal impact of the booster was likely due to booster dose timing relative to secondary waves of infection.

Conclusions. Our study suggests that prioritizing primary vaccinations would have a greater public health impact than prioritizing boosters among those with a primary vaccination. Booster vaccinations have the potential to be highly impactful; however, attention needs to be given to developing accurate forecasting tools so that vaccine distribution can be tailored to prevent subsequent waves of disease. 

Table of Contents

Background. 1

Methods. 2

Results. 5

Discussion. 7

Tables and Figures. 11

References. 25

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