A new lab study indicated that coronavirus vaccines developed by Moderna and Pfizer-BioNTech are significantly less efficacious against the Covid variant that first emerged in South Africa.

The study authors wrote that the percentage of protective antibodies that neutralised the variant — B.1.351 — was 12.4 times lower for Moderna’s Covid-19 shot than against the wild-type virus. While 10.3 times lower for Pfizer’s vaccine.

The new study, published in the journal Nature , showed a bigger drop than in previous lab studies testing the vaccines against manufactured forms of the variant.

For this study, the researchers used real forms of the variant collected from people who had infected with the virus.

The researchers noted that one specific mutation, E484K, appeared to be a “major contributor” to the B.1.351 variant’s ability to dodge the antibody response. E484K is not usually present in B.1.1.7, the variant first found in the UK.

To conduct the study, researchers gathered 10 blood samples from people who had received two doses of Pfizer’s vaccine, 28 days after their second dose. They also collected 12 samples from those who had received two doses of Moderna’s vaccine, 43 days after their second dose.

They then compared antibodies developed in the blood samples “neutralised” the original coronavirus, compared with real-life B.1.1.7 and B.1.351 coronavirus variants.

The study comes months after both the vaccine manufacturers declared that they were developing booster shots specifically to inhibit the B.1.351 variant.

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