Monday, March 1

Pfizer’s vaccine is not as effective with the South African variant



A laboratory study suggests that the South African variant of the coronavirus may reduce antibody protectionof the Pfizer / BioNTech vaccine by two-thirds, and it is unclear whether the injection will be effective against the mutation, the companies said Wednesday.

The study found that the vaccine was indeed capable of neutralizing the virus, but there is no evidence from human trials that the variant reduces the protection of the vaccine, the companies said. Despite this, they are making investments and talking to regulators about the development of an updated version of your mRNA vaccine or a booster shot, if needed.

For the study, scientists from companies and from 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 variant of coronavirus first discovered in South Africa, known as B.1.351. 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 on 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 most common version of the virus prevalent in 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’s unclear if that two-thirds reduction will make the vaccine ineffective against the variant that spreads all over the world.

However, UTMB professor and study co-author Pei-Yong Shi said he believes the Pfizer vaccine will probably protect against variant. ‘We don’t know what the minimum neutralization number is. We don’t have that cutoff line, ”he said, adding that he suspects the observed immune response will likely be 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 a lower antibody responsethan 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, I note. Health experts have said that it is the single most important factor in preventing stretched health systems from becoming overwhelmed.

“More work is needed to understand if 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 is effective against another variant first found in Brazil.

Modern published a correspondence in NEJM on Wednesday with similar data previously released elsewhere showing a six-fold drop in antibody levels versus 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.

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