COVID-19 vaccines, immunity, and new
variants: The role of T cells

The SARS-CoV-2 virus, like other viruses that have RNA as their genetic material, has a tendency to mutate constantlyTrusted Source. Consequently, numerous SARS-CoV-2 variants have emerged as the COVID-19 pandemic has progressed.

A few SARS-CoV-2 variants have shown increased transmissibility, with the World Health Organization (WHO)Trusted Source designating them as “variants of concern (VOC).”

These VOCs include the alpha (B.1.1.7), beta (B.1.351), delta (B.1.617.2), and gamma (P.1) that originated in the United Kingdom, South Africa, India, and Brazil, respectively. The Centers for Disease Control and Prevention (CDC) recently downgraded the epsilon variant (B.1.427/429) that originated in the United States from a VOC to a variant of interest.