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Pfizer COVID vaccine protects against worrying coronavirus variants

12 May, 2021

Data from Qatar provide strongest evidence yet that COVID-19 vaccines can stop strains thought to pose a threat to immunization efforts.

Qatar’s second wave of COVID-19 was a double whammy. In January, after months of relatively few cases and deaths, the Gulf nation saw a surge driven by the fast-spreading B.1.1.7 variant, which was first identified in the United Kingdom. Weeks later, the B.1.351 strain, which is linked to reinfections and dampened vaccine effectiveness, took hold.

Amid this storm, researchers in Qatar have found some of the strongest evidence yet that current vaccines can quell variants such as B.1.351. Clinical trials in South Africa — where B.1.351 was first identified — had suggested that vaccines would take a hit against such variants. But this study offers a fuller picture of what countries battling such variants can expect. 

People in Qatar who received two doses of the Pfizer–BioNTech vaccine were 75% less likely to develop a case of COVID-19 caused by B.1.351 than were unvaccinated people, and had near-total protection from severe disease caused by that strain.

The findings — published on 5 May in The New England Journal of Medicine1 — suggest that current RNA vaccines are a potent weapon against the most worrisome immune-evading variants. Pfizer, based in New York City, and BioNTech, in Mainz, Germany, are developing an updated RNA vaccine targeting B.1.351, as is Moderna, based in Cambridge, Massachusetts. Early results from Moderna’s efforts suggest that a booster shot of the updated vaccine triggers a strong response against B.1.351.

“I think this variant is probably the worst of all the variants we know,” says Laith Jamal Abu-Raddad, an infectious-disease epidemiologist at Weill Cornell Medicine—Qatar in Doha, who led the Qatari study. “We have the tools, despite these variants, to control at least the severe forms of infection — and this should work quite well on transmission.”

Weaker protection

Researchers in South Africa identified B.1.351 in late 2020, and it’s now the predominant strain there. Laboratory studies show that the variant harbours mutations that blunt the effects of virus-blocking antibodies, and trials suggest that some COVID-19 vaccines are significantly less effective against the strain than against others.

Early lab research suggested that RNA vaccines, including the Pfizer–BioNTech jab, would be weakened by B.1.351, but probably not fully compromised. In April, the companies announced that a small trial in South Africa had found the vaccine to be fully effective against B.1.351, but the study of 800 people recorded a total of just 6 infections caused by B.1.351 in the placebo group, so efficacy might have been much lower.

Abu-Raddad’s team analysed tens of thousands of COVID-19 cases that occurred between the start of Qatar’s vaccination campaign in late December and the end of March. Genome sequencing showed that B.1.1.7 and B.1.351 were the predominant coronavirus lineages during this period and, from mid-February, each accounted for about half of the country’s cases.

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