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Israeli Study Has Bad News on 'Breakthrough' Infections

South African variant of COVID can break through Pfizer vaccine, it finds
By Evann Gastaldo,  Newser Staff
Posted Apr 12, 2021 1:57 AM CDT

(Newser) – An Israeli study has disheartening news, though researchers are cautioning that more study is needed: The South African coronavirus variant can "break through" and infect those who have received the Pfizer vaccine, the study of around 800 people found. Half of the subjects had tested positive for COVID-19 two weeks or more after receiving one or more vaccine doses; the other half, which had matching characteristics to the first group, had also tested positive, but were unvaccinated, Haaretz reports. The South African variant, B.1.351, was responsible for 5.4% of the infections in the vaccinated lot—compared to just 0.7% among the unvaccinated.

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That means it was eight times more likely for a person in the vaccinated group to have been infected with that particular variant, suggesting the Pfizer vaccine is less effective against the South African variant than it is against the original virus and the British variant currently responsible for almost all of Israel's cases. But overall, B.1.351 was responsible for just 1% of all COVID cases among those studied, so researchers say to keep in mind the small sample size plus the fact that the study was not meant to deduce overall effectiveness against any particular variant, since it didn't look at overall infection rates. The study has also not yet been peer-reviewed, the Jerusalem Post reports. Pfizer has not commented, Reuters reports. (Read more coronavirus vaccine stories.)

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