Effectiveness of Homologous and Heterologous Covid-19 Boosters against Omicron
Emma K. Accorsi, Amadea Britton, Nong Shang, Katherine E. Fleming-Dutra, Ruth Link‐Gelles, Zachary Smith, Gordana Derado, Joseph D. Miller, Stephanie J. Schrag, Jennifer R. Verani
Abstract
To the Editor: For persons who received a single dose of the Ad26.COV2.S vaccine (Johnson & Johnson-Janssen) against coronavirus disease 2019 (Covid-19), a booster dose of a messenger RNA (mRNA) vaccine at least 2 months after the primary dose is recommended. Recipients of Ad26.COV2.S for both the primary and booster doses may receive a second booster dose of an mRNA Covid-19 vaccine at least 4 months after the first Ad26.COV2.S booster dose. 1 Immunogenicity data from a phase 1-2 clinical trial conducted before B.1.1.529 and the BA sublineages of omicron emerged showed that increases in the titers of binding and neutralizing antibodies with heterologous boosting were similar to or greater than the increases with homologous boosting. In a study involving U.S. veterans, data that were obtained during a period in which omicron was the predominant circulating variant also showed that among Ad26.COV2.S recipients, vaccine effectiveness against omicron infection was higher with heterologous boosting than with homologous boosting 3 ; however, data from the general adult population and on vaccine effectiveness over time are lacking. More than 18 million doses of the Ad26.COV2.S vaccine have been administered in the United States alone 4 ; therefore, data are needed on boosting strategies that are effective over time.