Single-shot Ad26.COV2.S COVID-19 vaccine lasts at least eight months and covers the delta variant, researchers report

BOSTON – As of the end of June 2021, more than 150 million Americans have been fully vaccinated against COVID-19. But questions remain about how long vaccinated people are protected against SARS-CoV-2, the virus that causes COVID-19, and whether they will be protected from the viral variants circulating in the United States and globally, including the new highly transmissible delta (B.1.617.2) variant.

In findings published in the New England Journal of Medicine, Dan H. Barouch, MD, PhD, director of Beth Israel Deaconess Medical Center’s (BIDMC) Center for Virology and Vaccine Research, and colleagues report on the durability of Johnson & Johnson’s Ad26.COV2.S vaccine in humans. The single-shot viral vector vaccine — developed in part by Barouch and colleagues at BIDMC — was also evaluated for its coverage against the alpha, beta, gamma, delta, epsilon and kappa SARS-CoV-2 variants.

“Our data show that the Ad26.COV2.S vaccine elicited durable immune responses with minimal decline for at least eight months, the timeframe examined, following immunization,” said Barouch, corresponding author of the paper and also professor of medicine at Harvard Medical School. “We also showed good neutralization coverage of the delta variant as well as other variants.”

Barouch and colleagues evaluated antibody and T cell responses against the first detected SARS-CoV-2 virus (known as WA1/2020) in 20 vaccinated individuals for eight months, or 239 days, after the single-shot or a two-shot vaccine regimen. Antibody responses were detected in all participants on day 239, and were relatively stable over time. 

The scientists also detected neutralizing antibodies against multiple SARS-CoV-2 variants, including B.1.617.2, also known as the delta variant, which is highly transmissible and spreading rapidly throughout the United Kingdom and United States and other parts of the world. 

Moreover, Barouch and colleagues report that neutralizing antibody coverage of variants improved over time. For example, at day 29 after vaccination, the scientists observed at 13-fold reduction in antibodies produced against the B.1.351 (or beta) variant compared with the original virus, WA1/2020. By day 239, however, the team observed only a 3-fold reduction. Improved coverage was also observed against the B.1.617.2 (or delta) variant over time.

“These data suggest an expansion of neutralizing antibody breadth with improved coverage of SARS-CoV-2 variants over time, including increased neutralizing antibody titers against these variants of concern, even in the absence of further boosting,” said Barouch, who is also a member of the Ragon Institute of MGH, MIT and Harvard. “Taken together, the durability of humoral and cellular immune responses following Ad26.COV2.S vaccination with increased neutralizing antibody responses to SARS-CoV-2 variants over time, including after single-shot vaccination, further support the use of the Ad26.COV2.S vaccine for the global COVID-19 pandemic.”

Co-authors included Kathryn E. Stephenson, MD, MPH, Jingyou Yu, PhD, Aiquan Chang, MS, Makda Gebre, MS, Katherine McMahan, BS, Jinyan Liu, PhD, Abishek Chandrashekar, MS, and Shivani Patel, BS, of BIDMC; Jerald Sadoff, MD, Mathieu Le Gars, PhD, Anne Marit de Groot, PhD, Macaya Douoguih, MD, Johan van Hoof, MD, and Hanneke Schuitemaker, PhD, of Janssen Vaccines & Prevention; Dirk Heerwegh, PhD, and Frank Struyf, MD, of Janssen Research & Development.

This work was supported by Janssen Vaccines & Prevention BV, the Ragon Institute of MGH, MIT, the Massachusetts Consortium on Pathogen Readiness (MassCPR), the Musk Foundation, the National Institutes of Health (CA260476). This project has been funded in part with federal funds from the Office of the Assistant Secretary for Preparedness and Response, Biomedical Advanced Research and Development Authority, under Other Transaction Agreement HHSO100201700018C.

Disclosure forms provided by the authors are available with the full text of this article. Barouch is a co-inventor on related vaccine patents.