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T Cell Response to Omicron Preserved With Prior COVID-19 Infection, Vaccination

In This Article

  • A recent study led by Massachusetts General Hospital investigators evaluated T cell immune responses to the Omicron variant
  • The results indicate that individuals with prior COVID-19 infection or vaccination have a robust T cell response against Omicron, despite low antibody responses
  • Individuals with booster vaccination showed enhanced T cell response against the variant

The recent Omicron variant of SARS-CoV-2 has been known to escape antibody responses, even in individuals who are vaccinated against COVID-19. However, a team led by Massachusetts General Hospital investigators conducted a recent study that revealed that T cell responses were largely preserved against Omicron in most individuals with prior COVID-19 infection or vaccination.

The team, including Anusha Nathan, a medical student working at the Ragon Institute of Mass General, MIT, and Harvard, Vivek Naranbhai, MBChB, PhD, DPhil, a hematology and oncology fellow at Mass General, Gaurav D. Gaiha, MD, DPhil, attending physician in the Division of Gastroenterology and principal investigator at the Ragon Institute, and colleagues, published the recent findings in Cell.

The team obtained blood samples from 76 vaccinated and unvaccinated adults, both with and without prior SARS-CoV-2 infection.

In adults with prior infection or vaccination, or both prior infection and vaccination, and booster vaccination, T cell responses were largely preserved against the Omicron spike protein. Participants with prior COVID-19 infection also showed responses against other proteins in the virus.

Even with a lack of antibody response, T cells in most individuals retained recognition of the variant. Although 20% of individuals showed reduced T cell response despite prior infection or vaccination, this poor response was linked to certain genetic characteristics. Booster vaccination appeared to enhance T cell response by twenty-fold.

These results indicate that most prior infected and vaccinated individuals will have a T cell response to Omicron and be protected against severe infection. Individuals with the booster vaccine have substantially increased T cell immunity and even greater protection against the variant.

The team noted that their findings regarding individuals with reduced T cell response to Omicron may indicate that the virus could evolve to escape T cells. This emphasizes the importance of taking continued precautions against COVID-19 and working to develop vaccines that will be resistant to future variants.

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