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A laboratory study suggests that the South African variant of the coronavirus may reduce the antibody protection of the Pfizer / BioNTech vaccine by two-thirds, and it is unclear whether the injection will be effective against the mutation, the companies said.
The study found that the vaccine was still capable of neutralizing the virus and there is still no evidence from trials 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 shot, if necessary.
South African scientists will meet Thursday to discuss the study. “I know that our scientists will meet to discuss it and advise the minister,” said health department spokesman Popo Maja. “We are not going to release a statement until our scientists tell us. We will also be guided by the regulator ”.
For the study, scientists from the companies and the University of Texas Medical Branch (UTMB) developed a modified virus that contained the same mutations found in the peak portion of the highly contagious coronavirus variant first discovered. in South Africa, known as B1351. The spike, 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 drawn from people who had received the vaccine and found a two-thirds reduction in the level of neutralizing antibodies compared to its effect on the more common version of the virus prevalent in the US trials.
Their findings were published in the New England Journal of Medicine (NEJM).
Because there is not yet an established benchmark for determining what level of antibodies is needed to protect against the virus, it is unclear whether that two-thirds reduction will render the vaccine ineffective against the variant that is spread around the world. .
However, UTMB professor and study co-author Pei-Yong Shi said he believed the Pfizer vaccine would likely protect against the variant.
“We don’t know what the minimum neutralization number is. We don’t have that cut-off line, ”he said, adding that he suspects the observed immune response is likely significantly above where it needs to be to provide protection.
This is because, in clinical trials, both the Pfizer / BioNTech vaccine and a similar injection of Moderna 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 help protect against serious illness and death, he noted. Health experts have said it’s the single most important factor in preventing stretched health systems from being overwhelmed.
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 antibody levels are protective.
Pfizer and BioNTech said they were doing similar lab work to understand whether their vaccine protects against another variant first found in Brazil.
Moderna published a correspondence in NEJM on Wednesday, with similar data previously released elsewhere showing a six-fold drop in antibody levels compared to the South African variant.
Moderna also said that the actual efficacy of its vaccine against the South African variant has yet to be determined. The company has previously said that it believes the vaccine will work against the variant.
• The title of this article was modified on February 18, 2021. It is the antibody protection that can be reduced by two thirds by the South African variant, not the vaccine protection as stated in a previous version.
