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Small Study Finds Two COVID Vaccines Effective against California Variant

Moderna and Novovax COVID-19 vaccines were found to be effective against California variant, but not another

Apr 15, 2021
Duke Health

DURHAM, NC—Two different COVID vaccines are predicted to be protective against a rapidly spreading variant of the SARS-CoV-2 virus that arose in California, known as B.1.429, CAL.20C, or 452R.V1, reports a Duke Health-led research team. However, the vaccines were found to be less effective against a variant that first emerged in South Africa, known as B.1.351 or 20H/501Y.V2.

The finding, appearing April 7, 2021, as a research letter in the New England Journal of Medicine, tested blood serum samples from people who had received either the Moderna vaccine (26 people) or a vaccine candidate from Novovax (23 people) that is yet to be authorized in the US.

Compared to the wild-type D614G variant, the California variant was 2 to 3 times less sensitive to antibodies from convalescent people than antibodies from those vaccinated. While the variant from South Africa was about 9 to 14 times less sensitive. These results suggest that the Moderna and Novovax vaccines are likely effective against the California variant, but not so much so against the South Africa variant.

The researchers did not test the Pfizer-BioNTech vaccine, but they inferred that the findings for the Moderna vaccine would be comparable due to the similarities of the technology used in the two vaccines.

A vaccine candidate from Novovax—which is expected to be considered for FDA authorization in upcoming weeks—also performed well in the researchers’ tests against the variant that arose in California, which has spread rapidly throughout the United States and 25 other countries. 

Both the Moderna and Novovax vaccines, however, saw significant drops in effectiveness against the variant first identified in South Africa, which remains a worrisome form of the virus.

“The good news is the California variant does not appear to be a problem for our current vaccines,” said author David Montefiori, PhD, professor and director of the Laboratory for AIDS Vaccine Research and Development in Duke’s Department of Surgery. “That’s important to know because this variant is now as prevalent in the US as the UK variant, both of which appear to be more contagious.”

In addition to Montefiori, study authors include Xiaoying Shen, Haili Tang, Rolando Pajon, Gale Smith, Gregory M. Glenn, Wei Shi, and Bette Korber.

- This press release was originally published on the Duke Health news website but may have been edited for length and accuracy