The COVID-19 vaccines developed by Pfizer and Moderna appear to offer significantly less protection from antibodies against the highly contagious variant that has emerged in South Africa, new studies show.
The studies, published on Wednesday in the New England Journal of Medicine, indicated that both vaccines produced much lower levels of neutralizing antibodies against the new strain, compared to the initial SARS-CoV-2 virus.
For the Pfizer study, scientists developed a modified virus that contained the same mutations carried on the peak portion of the South African variant, known as B.1.351.
The researchers tested the modified virus with blood drawn from people who received the vaccine.
They determined that there was a two-thirds reduction in the level of neutralizing antibodies compared to their performance with the most prevalent version of the virus being tested in the United States.
However, it is not clear whether the reduced antibody response will render the vaccine ineffective against the strain, as it is not known what level is needed to neutralize the virus.
“We don’t know what the minimum number of neutralization is. We don’t have that cut line, ”said the study’s co-author, Pei-Yong Shi.
Meanwhile, Moderna’s study found a six-fold decrease in antibody response against its vaccine variant.
The results were published as part of a letter from the Massachusetts-based company in the same newspaper.
But the researchers also warned that the effectiveness of the modern vaccine against the strain is not yet known.
The company said earlier that it believes 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.
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