Blood samples from recovered COVID-19 patients show that they and their vaccinated peers should be able to fend off the virus and its variants in future encounters.

That’s according to researchers with the National Institute of Allergy and Infectious Diseases, which analyzed samples from 30 people who recovered from COVID-19 before concerning variants became dominant in parts of the United States. They found signs that a key immune response remained active and able to fight the virus in these patients.

Immune system cells, called CD8+ T cells, recognized new virus variants, including B.1.1.7, first detected in the United Kingdom; B.1.351, found in the Republic of South Africa; and B.1.1.248, first seen in Brazil, reported Aaron A. R. Tobian, M.D., Ph.D., of the Johns Hopkins University School of Medicine. The CD8+ T cells detect parts of the virus protein on the surface of infected cells and kill those cells, weakening the disease, he said.

Larger studies are needed, but this small study’s results suggest that the T cell responses in recovered patients will offer robust protection, Tobian and colleagues concluded. What’s more, vaccinated individuals can also develop these T cells and should be protected as well, they said.

The study was published in Open Forum Infectious Diseases.