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. 2023 Nov 2;10(11):ofad511.
doi: 10.1093/ofid/ofad511. eCollection 2023 Nov.

Efficacy of Messenger RNA-1273 Against Severe Acute Respiratory Syndrome Coronavirus 2 Acquisition in Young Adults From March to December 2021

Kathryn E Stephenson  1   2 , Jasmine R Marcelin  3 , Audrey E Pettifor  4 , Holly Janes  5 , Elizabeth Brown  5 , Moni Neradilek  5 , Catherine Yen  6 , Jessica Andriesen  5 , Nicole Grunenberg  5 , Nicole Espy  5 , Meg Trahey  5 , Rebecca S B Fischer  7 , Christopher A DeSouza  8 , Joanna L Shisler  9 , Elizabeth Connick  10 , Eric R Houpt  11 , Helen Y Chu  12 , Russel J McCulloh  13 , Sylvia Becker-Dreps  4   14 , Nadja A Vielot  14 , Corey A Kalbaugh  15 , Kartik Cherabuddi  16 , Karen M Krueger  17 , Molly Rosenberg  18 , Richard N Greenberg  19 , Arnel Joaquin  20 , Lilly Cheng Immergluck  21 , Lawrence Corey  5   12   22 , James G Kublin  5
Affiliations

Efficacy of Messenger RNA-1273 Against Severe Acute Respiratory Syndrome Coronavirus 2 Acquisition in Young Adults From March to December 2021

Kathryn E Stephenson et al. Open Forum Infect Dis. .

Abstract

Background: The efficacy of messenger RNA (mRNA)-1273 against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is not well defined, particularly among young adults.

Methods: Adults aged 18-29 years with no known history of SARS-CoV-2 infection or prior vaccination for coronavirus disease 2019 (COVID-19) were recruited from 44 US sites from 24 March to 13 September 2021 and randomized 1:1 to immediate vaccination (receipt of 2 doses of mRNA-1273 vaccine at months 0 and 1) or the standard of care (receipt of COVID-19 vaccine). Randomized participants were followed up for SARS-CoV-2 infection measured by nasal swab testing and symptomatic COVID-19 measured by nasal swab testing plus symptom assessment and assessed for the primary efficacy outcome. A vaccine-declined observational group was also recruited from 16 June to 8 November 2021 and followed up for SARS-CoV-2 infection as specified for the randomized participants.

Results: The study enrolled 1149 in the randomized arms and 311 in the vaccine-declined group and collected >122 000 nasal swab samples. Based on randomized participants, the efficacy of 2 doses of mRNA-1273 vaccine against SARS-CoV-2 infection was 52.6% (95% confidence interval, -14.1% to 80.3%), with the majority of infections due to the Delta variant. Vaccine efficacy against symptomatic COVID-19 was 71.0% (95% confidence interval, -9.5% to 92.3%). Precision was limited owing to curtailed study enrollment and off-study vaccination censoring. The incidence of SARS-CoV-2 infection in the vaccine-declined group was 1.8 times higher than in the standard-of-care group.

Conclusions: mRNA-1273 vaccination reduced the incidence of SARS-CoV-2 infection from March to September 2021, but vaccination was only one factor influencing risk.

Clinical trials registration: NCT04811664.

Keywords: COVID-19; SARS-CoV-2 infection; lifestyle circumstances; mRNA-1273 vaccine.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts.

Figures

Figure 1.
Figure 1.
Consort diagram of randomized and observational groups. Abbreviations: COVID-19, coronavirus disease 2019; FAS, full analysis set; FAS-P, full analysis set with PCR data; mRNA, messenger RNA; PCR, polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 2.
Figure 2.
Vaccine efficacy against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, displayed as cumulative SARS-CoV-2 incidence by group, among baseline SARS-CoV-2–negative participants.
Figure 3.
Figure 3.
Baseline lifestyle circumstance, displayed as the proportions of participants in each group who reported masking (A) physical distancing (B) meeting with a group of 10 or more (C) or encountering others not wearing a mask (D) in the previous 2 weeks.
See this image and copyright information in PMC

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