Studies Find Current COVID-19 Vaccines Induce Robust Immunity Against Omicron Variant

Data suggest that omicron-specific CD8-positive T cell responses were more than 80% cross-reactive with the CD8-positive T cell response to the original strain of the virus.

Despite the omicron variant’s ability to evade neutralizing antibodies, researchers have found that cellular immunity induced by current COVID-19 vaccines provided robust protection against severe disease, according to a study conducted by researchers at the Beth Israel Deaconess Medical Center (BIDMC).

The transmissibility of the omicron variant is well-documented, with a record-breaking 1.35 million new COVID-19 infections reported on January 11, 2022—roughly 4 times higher than the number of daily infections seen in January 2021. As a highly mutated version of SARS-CoV-2, the omicron variant has been shown to cause breakthrough infections among the vaccinated due to its ability to evade neutralizing antibodies caused by vaccination.

To assess the efficacy of currently available COVID-19 vaccines against both the delta and omicron variants, researchers at BIDMC assessed samples from 47 individuals vaccinated with either the Johnson & Johnson or Pfizer-BioNTech vaccines. The findings were published in Nature.

“Our data provide immunological context for the observation that current vaccines still provide robust protection against severe disease and hospitalization due to the Omicron variant despite substantially reduced neutralizing antibody responses and increased breakthrough infection,” said corresponding author Dan H. Barouch, MD, PhD, director of the Center for Virology and Vaccine Research at BIDMC, in a press release.

Using samples from uninfected individuals who had received a COVID-19 vaccine, the team measured CD*-positive T cell and CD4-positive T cell responses to the original, Delta, and Omicron strains of the SARS-CoV-2 virus. Samples were taken 1 month and 8 months after vaccination and the researchers also assessed antibody responses to the variants.

The team observed minimal cross-reactive Omicron-specific neutralizing antibodies, which is consistent with previous research. In contrast, the data suggested that Omicron-specific CD8-positive T cell responses were more than 80% cross-reactive with the CD8-positive T cell response to the original strain of the virus. Similarly, more than 80% of Omicron-specific CD4-positive T cells demonstrated cross-reactivity, although responses could vary among individuals, according to the study.

“Given the role of CD8-positive T cells in clearance of viral infections, it is likely that cellular immunity contributes substantially to vaccine protection against severe SARS-CoV-2 disease,” Barouch said in the press release. “This may be particularly relevant for Omicron, which dramatically evades neutralizing antibody responses.”

REFERENCE

Current COVID-19 Vaccines Induce Robust Cellular Immunity Against Omicron Variant, Researchers Demonstrate. News release; Beth Israel Deaconess Medical Center. January 31, 2022. Accessed February 1, 2022. https://www.bidmc.org/about-bidmc/news/2022/01/current-covid-19-vaccines-induce-cellular-immunity-against-omicron