Pfizer Shot Elicits Fewer Antibodies to South Africa Strain

Pfizer Inc. and BioNTech SE’s Covid-19 vaccine stimulated roughly two-thirds lower levels of neutralizing antibodies against the South African variant of the coronavirus in a lab study.

The Pfizer results are part of tests of its vaccine against a lab-created virus that had all the mutations found in the South African variant, which is thought to spread faster than earlier versions. The study released Wednesday showed reduced neutralization of the South Africa-like virus by blood from people who had been immunized with the Pfizer-BioNTech vaccine. The companies expect their vaccine will still work against the variant.

All of the blood samples from vaccinated patients still showed significant levels of neutralizing antibody against the South Africa variant, the researchers said. The study was conducted by Pfizer, BioNTech and researchers at the University of Texas Medical Branch at Galveston and published in the New England Journal of Medicine.

What Bloomberg Intelligence Says

Suggesting vaccine updates are needed, fresh data for Pfizer-BioNTech’s Covid-19 vaccine again show some loss of activity against the B.1.351 (South Africa) variant. Our analysis suggests that AstraZeneca’s vaccine efficacy may be most affected, possibly driven by its design. Only a head-to-head comparison will decipher the real-world effect of this variant on vaccine efficacy.

-- Pharma analyst Sam Fazeli

Read the research here.

A separate study by researchers from the National Institute of Allergy and Infectious Diseases and Moderna Inc. also looked at how that company’s vaccine performed against the South Africa variant in the lab, and found a significant reduction in coronavirus-fighting antibodies. These neutralizing antibodies were reduced by a factor of 6.4, compared with levels produced against earlier versions of the virus, when the full group of South Africa mutations were examined.

Stumbling Block

What the lab data means in practice remains to be seen. “It is unclear what effect a reduction in neutralization by approximately two-thirds would have” on protection from Covid-19 caused by the South Africa variant, the Pfizer study concluded.

The mutant virus has become a stumbling block for vaccine campaigns, with South Africa halting the rollout of AstraZeneca Plc’s shot after a study showed it didn’t work as well in preventing mild illness involving the variant first identified there. AstraZeneca is working to revise its vaccine by fall, while Moderna Inc. is working on booster shots.

Pfizer and BioNTech said in a statement that there’s no real-world evidence that the South African variant can elude their shot. Still, they said they’re getting ready to develop an updated vaccine or booster if need be.

The partners said they’re also testing whether the vaccine works against a variant that has emerged in Brazil, as well as against other mutant strains.

‘Not Huge Changes’

The findings shouldn’t stand in the way of South Africa using the Pfizer shots, according to the Africa Centers for Disease Control and Prevention. The government has ordered 20 million Pfizer vaccines.

“What we are seeing based on the studies is not huge changes in neutralizing the antibodies of this virus,” Africa CDC Director John Nkengasong said Thursday in an online briefing.

Pfizer declined to comment further on the impact the lab study would have on the rollout of its inoculation in South Africa, referring to its statement. The World Health Organization said the data from the study needs to be scrutinized further before any decision is taken on the use of the shots.

Meanwhile, a shot from Johnson & Johnson prevented hospitalizations and deaths from Covid in a large study but was less effective at preventing infections in South Africa than elsewhere. A vaccine developed by Novavax Inc. also was less effective in South Africa in a study.

©2021 Bloomberg L.P.

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