- In one study, the Pfizer and BioNTech vaccine worked against laboratory-made coronaviruses, similar to variants that spread in the UK and South Africa.
- Small differences in the vaccine’s performance against the mutations, compared to the original virus, were “unlikely to lead to a significant reduction” in efficacy.
- The Pfizer-BioNTech vaccine has not yet been tested against actual coronavirus variants.
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The COVID-19 vaccine co-developed by Pfizer and BioNTech works against laboratory-made coronaviruses that are similar to variants found in the United Kingdom and South Africa, the manufacturers announced on Wednesday.
Studies conducted by Pfizer and the University of Texas have shown “small differences” in how well antibodies produced by the Pfizer vaccine bound and killed viruses made in the laboratory, compared to how well they worked against the original virus.
But these differences were “unlikely to lead to a significant reduction in the vaccine’s effectiveness,” BioNTech said in a press release.
The vaccine from Pfizer and BioNTech was 95% effective in protecting against the original coronavirus in tests conducted in 2020.
In the new study, Pfizer tested three different “pseudoviruses” that it had designed to have some of the mutations found in the UK and South Africa variants. The variant found in South Africa has a mutation called K417N, which has been shown to avoids antibodies in laboratory studies – the variant made in the laboratory did not have this mutation.
The Pfizer researchers looked at how well the antibodies worked, which is an aspect of the immune system’s defense against the coronavirus. There is no agreement on how “protection against COVID-19” is defined, the study’s authors said in the article, recognizing this as a weakness of the study.
The results are from a prepress study and have not yet been published in a peer-reviewed journal for examination by experts.
The variant found in the United Kingdom, B.1.1.7, was found in several states in the USA, as well as in countries around the world. The variant found in South Africa, 501Y.V2, has not yet been identified in the USA.
Pfizer said on January 20 that it tested its vaccine with the variant found in the UK and worked in laboratory studies administered by the company, but this latest research was its first test against the South African variant.
The sample size was small, and the scientists did not perform any statistical significance tests, which is a way for researchers to assess whether the results could be random.
Moderna announced on Monday that its vaccine resisted well against B.1.1.7, the variant found in the UK, but small-scale laboratory tests showed that the injection worked less against the 501 variant found in South Africa. Y.V2.
“Gold standard” would be testing against the real-life variant
In the latest Pfizer study, scientists tested the pseudovirus against antibodies in 12 blood samples from people who received two injections of the Pfizer vaccine two or four weeks earlier. They then looked at how well the antibodies worked against pseudovirus variants, compared to the original strain.
“The gold standard would be to test antibodies against the variants themselves to understand how their unique mutation constellation can affect the natural immunity or protection of a vaccine,” Dr. Jason McLellan, a structural biologist at the University of Texas at Austin, told Wall. Street Journal. McLellan studied how coronavirus proteins interact with antibodies, but was not involved in the Pfizer study.
Rafael Casellas, a molecular immunologist at the National Institutes of Health (NIH), told the Journal that it was important to keep monitoring for coronavirus variants and assess whether vaccines and other treatments need to be updated or whether booster doses are needed.
“We cannot deal with this virus lightly,” he said. “We just don’t have enough information, so we need to be cautious.”
We do not know how long immunity lasts after receiving a vaccine, both for variants of the coronavirus and for the original virus.
Pfizer said on Tuesday that it was already working on booster vaccines that protect against coronavirus variants. Moderna said on Monday it would develop a new version of its COVID-19 shot to combat 501.Y.V2, the variant found in South Africa.
“Pfizer and BioNTech will continue to monitor emerging strains of SARS-CoV-2 and conduct studies to monitor the vaccine’s effectiveness in the real world,” the companies said.