Pfizer says the South African variant can significantly reduce the protection of the vaccine

(Reuters) – A laboratory study suggests that the South African variant of the coronavirus could reduce antibody protection against the Pfizer Inc / BioNTech SE vaccine by two-thirds, and it is not clear whether the shot is effective against the mutation. Said Wednesday.

The study found that the vaccine was still able to neutralize the virus, and there is still no evidence from trials in humans that the variant reduces the protection of the vaccine, the companies said.

Yet they make investments and talk to regulators about developing an updated version of their mRNA vaccine or an enhancer shot, if necessary.

For the study, scientists from the companies and the University of Texas Medical Branch (UTMB) developed a engineered virus that contained the same mutations found at the peak portion of the highly contagious coronavirus variant first discovered in South Africa, known as B .1.351, contains. The peak, which is used by the virus to enter human cells, is the primary target of many COVID-19 vaccines.

Researchers tested the engineered virus against blood taken from people who received the vaccine, and found that the level of neutralizing antibodies decreased by two-thirds compared to its effect on the most common version of the virus found in US trials prevent.

Their findings were published in the New England Journal of Medicine (NEJM).

Because there is no standard yet to determine which antibodies are needed to protect against the virus, it is unclear whether reducing two-thirds will make the vaccine ineffective against the variant that is spreading around the world.

However, UTMB professor and co-author of the study, Pei-Yong Shi, said he believes the Pfizer vaccine is likely to be protective against the variant.

‘We do not know what the minimum neutralizing number is. We do not have the cut-off point, ”he said, adding that he suspected that the observed immune response was likely to be significantly higher than it should be to provide protection.

This is because both the Pfizer / BioNTech vaccine and a similar uptake of Moderna Inc in clinical trials provide some protection after a single dose with an antibody response lower than the reduced levels shown by the South African variant in the laboratory study. caused.

Even if the variant in question significantly reduces its effectiveness, the vaccine should still protect against serious diseases and death, he noted. Health experts said it was the most important factor in preventing protracted healthcare 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 correlates of protection – the criteria for determining which antibody levels are protective.

Pfizer and BioNTech said they are doing similar laboratory work to understand if their vaccine is effective against another variant first found in Brazil.

Moderna published a correspondence in NEJM on Wednesday with similar data previously announced elsewhere, which shows a six-fold drop in antibody levels compared to the South African variant.

Moderna also said that the actual effectiveness of the vaccine against the South African variant has yet to be determined. The company had earlier said it believed the vaccine would work against the variant.