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COVID-19 vaccines developed by Pfizer and Moderna appear to offer significantly less antibody protection against the highly-contagious variant that emerged in South Africa, new studies show.
The studies, published Wednesday in the New England Journal of Medicine, indicated that both vaccines elicited much lower levels of neutralizing antibodies against the new strain, compared to the initial SARS-CoV-2 virus.
For the Pfizer study, scientists developed an engineered virus that contained the same mutations carried on the spike portion of the South African variant, known as B.1.351.
Researchers tested the engineered virus against blood taken from people who had been given the vaccine.
They determined there was a two-thirds reduction in the level of neutralizing antibodies compared to how it performed with the most prevalent version of the virus in US trials.
However, it’s unclear if reduced antibody response will render the vaccine ineffective against the strain, since it’s not known what level is necessary to neutralize the virus.
“We don’t know what the minimum neutralizing number is. We don’t have that cutoff line,” study co-author Pei-Yong Shi said.
Meanwhile, the Moderna study found a six-fold decrease in antibody response against the variant from its vaccine.
The results were published as part of a letter from the Massachusetts-based company in the same journal.
But researchers similarly warned that the effectiveness of the Moderna vaccine against the strain is still not known.
The company has previously said that it believes that the vaccine will offer protection against the variant.
There are currently 19 reported cases of B.1.351 in the United States in 10 states, according to the Centers for Disease Control and prevention.
With Post wires
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