Janssen COVID-19 Vaccine Demonstrates 85% Effectiveness against Omicron-Related Hospitalization

New Jersey-based Johnson & Johnson (J&J) announced on December 30, 2021, new preliminary results from the South African Phase 3b Sisonke study, which showed that a homologous (same vaccine) booster shot of the Johnson & Johnson COVID-19 vaccine (Janssen, Ad26.COV2.S) demonstrated 85% effectiveness against COVID-19-related hospitalization.

The non-peer-reviewed study published (Dec. 29) was conducted by the South African Medical Research Council, which showed that the J&J booster reduced the risk of hospitalization from COVID-19 among healthcare workers in South Africa after Omicron became the dominant variant.

During mid-November to mid-December 2021, the frequency of Omicron increased from 82 to 98% of COVID-19 cases in South Africa, as reported by GISAID, an initiative that provides COVID-19 data.

A second, separate analysis of the immune response to different vaccine regimens, conducted by Beth Israel Deaconess Medical Center, demonstrated that a heterologous booster (different vaccine) of the Johnson & Johnson COVID-19 vaccine in individuals who initially received the BNT162b2 mRNA vaccine generated a 41-fold increase in neutralizing antibody responses by four weeks following the boost and a 5-fold increase in CD8+ T-cells to Omicron by two weeks.

A homologous boost with BNT162b2 generated a 17-fold increase in neutralizing antibodies by four weeks following the boost and a 1.4-fold increase in CD8+ T-cells by two weeks.

The increase in CD8+ T-cells generated by the J&J vaccine may be key to explaining the high levels of effectiveness against severe COVID-19 disease and hospitalization in the Sisonke 2 study, as the Omicron variant has been shown to escape neutralizing antibodies.

"This adds to our growing body of evidence which shows that the effectiveness of the Johnson & Johnson COVID-19 vaccine remains strong and stable over time, including against circulating variants such as Omicron and Delta," said Mathai Mammen, M.D., Ph.D., Global Head, Janssen Research & Development, LLC, J&J, in a press release.

"We believe that the protection could be due to the robust T-cell responses induced by the J&J COVID-19 vaccine."

"Furthermore, these data suggest that Omicron is not affecting the T-cell responses generated by our vaccine."

The Janssen COVID-19 Vaccine (Ad26.COV2.S) vaccine is a recombinant, replication-incompetent adenovirus serotype 26 (Ad26) vector encoding a full-length and stabilized SARS-CoV-2 spike protein. This vaccine does not contain adjuvants, preservatives, materials of animal origin, or fetal tissue.