Sheba Hospital last month began giving a fourth vaccine to more than 270 medical workers — 154 who received the Pfizer-Biontech vaccine and another 120 who received the Moderna vaccine. They were all previously vaccinated three times with the Pfizer-Biontech vaccine.
The clinical trial found that both groups showed an increase in antibodies “slightly higher” than following the third dose of the vaccine last year. But, she said, the increased antibody did not prevent the spread of the omicron.
“Despite increased antibody levels, the fourth vaccine offers only partial defense against the virus … The vaccines, which were more effective against the earlier variants, offer less protection compared to Omicron,” said Dr. Gilly Regev Yochai, director of the hospital’s infectious disease unit.
The initial findings raised questions about Israel’s decision to provide a second booster dose – and a fourth overall – to its population over the age of 60. The government says more than 500,000 people have received the second dose in recent weeks.
Dr. Nahman Asch, director of the Israeli Ministry of Health, said the research does not mean that the fourth vaccine effort was wrong. “It brings the antibody level back to what it was at the start of the third booster. “This is of great importance, especially among the older population,” he told Channel 13 TV.
But he said the research would be taken into account as authorities debate whether to extend the additional booster-dose campaign to the entire population.
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