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Course: Durability of the Single-Dose Ad26.COV2.S Vaccine in the Prevention of COVID-19 Infections and Hospitalizations in the US Before and During the Delta Variant Surge

CME Credits: 1.00

Released: 2022-03-17

Key Points

Question What is the durability of the Ad26.COV2.S COVID vaccine effectiveness before and during the Delta variant surge in the US?
Findings Among 422,034 vaccinated and 1,645,397 matched unvaccinated individuals across the US, vaccine effectiveness was estimated to be 76% for COVID-19 infection and 81% for hospitalizations for at least 180 days after vaccination before and during the Delta variant surge.
Meaning In this study, the Ad26.COV2.S COVID-19 vaccine was associated with high and durable effectiveness in clinical practice, including against the Delta variant.

Abstract

Importance Vaccination against the SARS-CoV-2 virus is critical to control the pandemic. Randomized clinical trials demonstrated efficacy of the single-dose Ad26.COV2.S COVID-19 vaccine, but data on longer-term protection in clinical practice and effectiveness against variants are needed.
Objective To assess the association between receiving the Ad26.COV2.S vaccine and COVID-19–related infections and hospitalizations before and during the Delta variant surge.
Design, Setting, and Participants This cohort study included adults aged 18 years and older who were newly Ad26.COV2.S-vaccinated matched to as many as 10 unvaccinated individuals by date, location, age, sex, and comorbidity index. This was followed by 1:4 propensity score matching on COVID-19 risk factors. Data were collected from US insurance claims data from March 1, 2020, through August 31, 2021.
Exposures Vaccination with Ad26.COV2.S vs no vaccination.
Main Outcomes and Measures Vaccine effectiveness (VE) was estimated for recorded COVID-19 infection and COVID-19–related hospitalization, nationwide and in subgroups by age, high-risk factors, calendar time, and states with high incidences of the Delta variant. VE estimates were corrected for underrecording of vaccinations in insurance data.
Results Among 422,034 vaccinated individuals (mean [SD] age, 54.7 [17.4] years; 236,437 [56.0%] women) and 1,645,397 matched unvaccinated individuals (mean [SD] age, 54.5 [17.5] years; 922,937 [56.1%] women), VE was 76% (95% CI, 75%-77%) for COVID-19 infections and 81% (95% CI, 78%-82%) for COVID-19–related hospitalizations. VE was stable for at least 180 days after vaccination and over calendar time. Among states with high Delta variant incidence, VE during June to August 2021 was 74% (95% CI, 71%-77%) for infections and 81% (95% CI, 75%-86%) for hospitalizations. VE for COVID-19 was higher in individuals younger than 65 years (78%; 95% CI, 77%-79%) and lower in immunocompromised patients (64%; 95% CI, 59%-68%). All estimates were corrected for vaccination underrecording; uncorrected VE, which served as a lower bound, was 66% (95% CI, 64%-67%) for any recorded COVID-19 infection and 72% (95% CI, 69%-74%) for COVID-19–related hospitalization.
Conclusions and Relevance This cohort study in US clinical practice showed stable VE of Ad26.COV2.S for at least 6 months before as well as during the time the Delta variant emerged and became dominant.


Educational Objective
To identify the key insights or developments described in this article


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