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

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SOME SARS-CoV-2 variants of concern can evade neutralizing antibodies in vaccinated individuals, raising concerns about the ability of vaccines to protect against them.

Covid-19 vaccines also result in a T cell response that facilitates recovery from the disease.

A recent study investigating variants of concern in individuals immunized with the Moderna and Pfizer Covid-19 vaccines found that the T cell response, unlike the antibody response, was not majorly disrupted.

These results suggest that an intact T cell response to variants in vaccinated individuals may help prevent severe Covid-19.

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.

Stay informed with live updates on the current Covid-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.

A prior SARS-CoV-2 infection or immunization with a Covid-19 vaccine results in the production of neutralizing antibodies by B lymphocytes, or B cells.

They bind to the spike proteinTrusted Source of the virus and inhibit its ability to infect the host cells.

VOCs carry mutations on the spike protein that neutralizing antibodies recognize, potentially reducing vaccinated individuals’ immunity to these variants.

For example, the AstraZeneca vaccine is effective against the alpha variant but shows a drastic decline in efficacy against the beta variant.

Furthermore, the beta variant also exhibited reduced susceptibility to neutralizing antibodies in clinical trials involving the same vaccine.

How new variants can escape neutralizing antibodies has raised concerns about the ability of vaccines to protect against current and future variants.

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