A laboratory study suggests that the South African variant of the coronavirus may reduce antibody protection from the Pfizer Inc/BioNTech SE vaccine by two-thirds, and it is not clear if the shot will be effective against the mutation, the companies said on February 17.
The study found the vaccine was still able to neutralize the virus and there is not yet evidence from trials in people that the variant reduces vaccine protection, 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 needed.
For the study, scientists from the companies and the University of Texas Medical Branch (UTMB) developed an engineered virus that contained the same mutations carried on the spike portion of the highly contagious coronavirus variant 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.
Researchers tested the engineered virus against blood taken from people who had been given the vaccine and found a two-thirds reduction in the level of neutralizing antibodies compared with its effect on the most common version of the virus prevalent in U.S. trials.
Their findings were published in the New England Journal of Medicine (NEJM).
Because there is no established benchmark yet to determine what level of antibodies are needed to protect against the virus, it is unclear whether that two-thirds reduction will render the vaccine ineffective against the variant spreading around the world.
The other COVID vaccine maker Moderna also said the actual efficacy of its vaccine against the South African variant is yet to be determined. The company has previously said it believes the vaccine will work against the variant.
Experts say that more work is needed to understand whether the vaccine works against the South African variant, including clinical trials and the development of correlates of protection – the benchmarks to determine what antibody levels are protective.