Assessing the Clinical and Economic Impact of Varying Efficacy of COVID-19 Reminders in the United States

In a recent study published on medRxiv* preprint server, researchers used an economic model to project the differences in clinical and economic impact of messenger ribonucleic acid (mRNA)-1273 and BNT162b2 booster vaccines among the adult US population ( US) for 2022.

Study: Clinical and Economic Impact of Differential COVID-19 Vaccine Efficacy in the United States. Image Credit: Lightspring/Shutterstock

Real-world data and predictive modeling have shown that protection against coronavirus disease 2019 (COVID-19) varies by vaccine type, number of vaccine doses, and time since vaccination. Additionally, initial vaccine efficacy (VE) and its decline differ for circulating SARS-CoV-2 variants.

About the study

In the present study, researchers explored three scenarios to match three mRNA Booster market share scenarios:

i) where the booster mix given in December 2021 continued throughout 2022, called the current scenario,

ii) where only the mRNA-1273 booster would continue in 2022, called the mRNA-1273 scenario and,

iii) where only the BNT162b2 booster would continue in 2022, called scenario BNT162b2.

In the United States, 94.7% and 93.7% of people who received the BNT162b2 or mRNA-1273 primary series also received the BNT162b2 or mRNA-1273 boosters, respectively. However, among those who received the Ad26.COV2.S vaccine during the primary series, 41.8% received the mRNA-1273 boost while 31.1% received the BNT162b2 boost.

Additionally, they performed sensitivity analyzes to investigate the effect of COVID-19 prevalence in unvaccinated and VE individuals using values ​​predicted by the model. The economic analyzes in the study were done from the perspective of health care in the United States. Since the present study used an analytical decision model, it used a decision tree to estimate the consequences and costs of COVID-19.

The study model projected three specific booster market share scenarios for 2022 to examine the hypothetical impact of changing the booster mix to 100% mRNA-1273 or 100% BNT162b2. It estimated the size of the US adult population and the number of patients receiving only the primary series and the primary series with a booster dose and calculated the number of infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV -2) in each group.

For each month, the model grouped study participants into unvaccinated, vaccinated with the primary series, and vaccinated with the primary plus booster series. For the latter two groups, the researchers reduced the incidence of infection based on VE and recalculated each month to account for the decline based on time since vaccination. They used May as the anchor month to calculate the period since the primary series for VE calculations for each month for those who received the primary series in 2021.

For those who received a booster dose in 2021, the team assumed the booster was received in November. The VE estimate for the primary series was an average of the adjusted decreasing VE weighted by the proportion of people receiving each primary series. Similarly, they estimated the booster VE as a weighted average of decreasing adjusted VE and the proportion of people receiving each booster.

The primary outcomes of the study were outpatient visits, hospitalizations, and mortality due to COVID-19 in 2022.

Study results

For the current scenario, the model predicted 3.4 million hospitalizations, 65.2 million outpatient visits, and 636,100 deaths. The mRNA-1273 scenario reduced these results, while the BNT162b2 scenario increased them compared to the current scenario.

January 2022 results were excluded from the analysis when case incidence increased due to the concerning new SARS-CoV-2 (VOC) variant Omicron. Reported COVID-19 outpatient visits, hospitalizations and deaths between February and December 2022 were 17.9 million, 965,600 and 182,800, respectively. Over this period, mRNA-1273 boosts reduced results by 2.3% to 2.8%, while use of BNT126b2 increased them by approximately 1.4% to 2.1% .

In all scenarios examined during the study, all three study outcomes increased when EV was lower and decreased when EV was higher. Nevertheless, the mRNA-1273 boost prevented COVID-19 better than the BNT162b2 boost.

Although the incidence of COVID-19 is highly uncertain for 2022, varying incidence rates (low to high) did not change the overall model results. In the 100% mRNA-1273 recall scenario, there were fewer outpatient visits, hospitalizations, and deaths. In addition, it also reduced the associated costs compared to the current scenario and 100% of BNT162b2.


Regardless of the incidence of COVID-19 or the circulating variant of SARS-CoV-2, study data indicated that mRNA-1273 boost was more effective than BNT162b2 boost in preventing cases of COVID-19 and hospitalization over time. Thus, increasing the number of US citizens receiving the mRNA-1273 booster could reduce the number of COVID-19 cases and associated costs in 2022.

*Important Notice

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

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