A laboratory study suggests that the South African variant of the coronavirus may reduce the antibody protection of the Pfizer Inc / BioNTech SE vaccine by two-thirds, and it is unclear whether the injection will be effective against the mutation, the companies said on Wednesday .
The study found that the vaccine is still capable of neutralizing the virus and there is still no evidence of testing in people that the variant reduces the protection of the vaccine, the companies said.
Still, they are making investments and talking to regulators about developing an updated version of their mRNA vaccine or a booster injection, if necessary.
For the study, scientists from the companies and the University of Texas Medical Branch (UTMB) developed a modified virus that contained the same mutations carried in the peak portion of the highly contagious coronavirus variant first discovered in South Africa, known as B. 1,351. The peak, used by the virus to enter human cells, is the primary target of many COVID-19 vaccines.
The researchers tested the modified virus against blood collected from people who received the vaccine and found a two-third reduction in the level of neutralizing antibodies compared to its effect on the most common version of the virus prevalent in tests in the United States.
Their findings were published in the New England Journal of Medicine (NEJM).
As there is still no established benchmark to determine the level of antibodies needed to protect against the virus, it is not clear whether this two-thirds reduction will render the vaccine ineffective against the variant that spreads around the world.
However, UTMB professor and co-author of the study, Pei-Yong Shi, said he believed that the Pfizer vaccine is likely to protect against the variant.
“We don’t know what the minimum number of neutralization is. We don’t have that cut-off line,” he said, adding that he suspects that the observed immune response is likely to be significantly above what is necessary to provide protection.
This is because, in clinical trials, both the Pfizer / BioNTech vaccine and a similar injection by Moderna Inc conferred some protection after a single dose with an antibody response lower than the reduced levels caused by the South African variant in the laboratory study.
Even if the worrying variant significantly reduces effectiveness, the vaccine should still help protect against serious illness and death, he noted. Health experts say this is the most important factor in preventing overburdened health systems from becoming overburdened.
More work is needed to understand whether the vaccine works against the South African variant, Shi said, including clinical trials and the development of protective correlates – the benchmarks for determining which levels of antibodies are protective.
Pfizer and BioNTech said they are doing similar laboratory work to understand whether their vaccine is effective against another variant initially found in Brazil.
Moderna published a correspondence in the NEJM on Wednesday with similar data previously released elsewhere that showed a six-fold drop in antibody levels compared to the South African variant.
Moderna also said that the real effectiveness of its vaccine against the South African variant has yet to be determined. The company said earlier that it believes the vaccine will work against the variant.