My Patients Ask — Are COVID vaccines effective against variant strains?

There has been some concern that immunity afforded by the vaccines may not be effective against variants of the COVID virus. What do we know as of today?

Experts generally believe that the vaccines will still provide some protection against the variants.

Research has already indicated that both the Pfizer and Moderna vaccines are likely to protect against the B.1.1.7 variant (i.e., the “U.K. variant”) (Muik, bioRxiv — preprint; Collier, medRxiv — preprint; Wu, bioRxiv — preprint).

The Moderna vaccine also appears to be likely to protect against other variants with mutations within the spike protein (such as EHC-083E, a variant identified in Atlanta, GA), although neutralization efficacy against this strain was diminished compared to the original SARS-CoV-2 strain (Edara, JAMA 2021).

As explained by the World Health Organization’s Chief Scientist, “these vaccines elicit a fairly broad immune response, a host of antibodies and cell-mediated immune responses … so a couple of changes or mutations in the virus should not make these vaccines ineffective.”

While there is evidence that both the Moderna and the Pfizer vaccines have diminished efficacy against the B.1.351 variant (i.e., the “South African variant”), the vaccines are still considered to provide sufficient immunity to protect against this variant (Wu, bioRxiv — preprint; Tada, bioRxiv — preprint).

Out of caution, however, Moderna has announced plans to develop a booster shot to target this variant.

On the other hand, these variants may be less responsive to monoclonal antibody therapy for COVID, as such therapies each represent an antibody to just one very small part of the virus, which could be changed in a variant.

Laboratory research has shown that at least two classes of monoclonal antibodies that target COVID are unable to neutralize SARS-CoV-2 501Y.V2 (i.e., the “South African variant”) (Wibmer, bioRxiv – preprint).

This blog was accurate as of the day of posting. However, as the COVID-19 pandemic rapidly evolves and the scientific community’s understanding of the novel coronavirus and the COVID vaccine develops, the information above may have changed since it was last updated. While I aim to keep all of my blogs on COVID and the COVID vaccine up to date, please visit online resources provided by the CDC, WHO, and your local public health department to stay informed on the latest news.

© Copyright WLL, INC. 2021. This blog provides a wide variety of general health information only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment from your regular physician. If you are concerned about your health, take what you learn from this blog and meet with your personal doctor to discuss your concerns.


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