CAPE TOWN – A booster dose of Johnson & Johnson Inc.’s single-dose COVID-19 vaccine was 84% effective in preventing hospitalization in South African healthcare workers who became infected as the Omicron variant spread, researchers said Thursday.
The real-world study, which has not been peer-reviewed, was based on a second dose of the J&J vaccine administered to 69,092 workers between November 15 and December 20.
An initial inoculation course has been shown to provide only greatly reduced protection against infection with Omicron, which spreads rapidly through many countries after only being identified in late November in southern Africa and Hong Kong.
However, several studies have suggested that a booster dose provides significant protection against severe disease from the variant.
The South African study showed that the efficacy of the J&J vaccine to prevent hospitalization increased from 63% shortly after a booster was administered to 84% 14 days later. Efficiency reached 85% one to two months after boost.
“It assures us that COVID-19 vaccines remain effective for the purpose for which they were designed, which is to protect humans from serious illness and death,” said Linda-Gail Bekker, co-lead investigator of the study.
“This is yet another proof that we have not lost that influence, even in the light of a highly mutated variant.”
Bekker said the jury was “still out” on the question of further boosters of the J&J shot.
“What we’re showing is that two doses really restores full protection, and I do not think we can extrapolate from this that we will need a third or fourth boost at all.”
Researchers said their analysis had several limitations, including short follow-up times, which averaged eight days for healthcare professionals who had received their boost within the previous 13 days, or 32 days for those who had been boosted for 1-2 months previously. , and which could distort. overall vaccine efficacy.
Another South African-based study this month found that a first round of inoculation with two doses of Pfizer-BioNTech’s COVID-19 vaccine had been less effective in South Africa in keeping people infected with the virus out of hospital since the Omicron variant appeared. .
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