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Israeli study: Fourth shot not effective vs. Omicron

The fourth dose campaign was part of Israel's strategy to tackle the fifth wave

An Israeli study on the efficacy of a fourth COVID shot shows that it has been less effective against the Omicron variant – a study which comes after more than half a million Israelis already took the fourth vaccine dose.

“The vaccine, which was very effective against the previous strains, is less effective against the Omicron strain,” said Prof. Gili Regev-Yochay who was one of the lead researchers for the Sheba Hospital study.

“We see an increase in antibodies, higher than after the third dose," she said. "However, we see many infected with Omicron who received the fourth dose. Granted, a bit less than in the control group, but still a lot of infections.”

The vaccine was geared toward the original variant of COVID-19 which could explain its lower efficacy in subsequent strains.

The study followed 150 healthy hospital staff members and began on Dec. 27.

Israel was the first – and only country – to roll out a fourth shot for the immunocompromised in December and for the the 60 and older population earlier this month. Banking on the success of its pioneering third shot, which managed to get the Delta wave under control, Prime Minister Naftali Bennett pinned his hopes on a fourth dose to slow the spread of Omicron.

Since then, nearly 540,000 Israelis have taken the latest booster including Finance Minister Avigdor Liberman, who contracted COVID just days after he received his fourth shot.

On Jan. 15 some 19,200 people who tested positive for COVID were considered fully vaccinated while 10,000 were unvaccinated and 2,700 were only partially vaccinated, according to the official Health Ministry dashboard.

Graph from the Israeli Health Ministry dashboard ( with English translation

On the same date, 434 people were in serious condition. Of that group, 194 were vaccinated, 135 were not and 37 had vaccines that were out of date which likely indicates that their Green Passport had expired.

The Omicron wave, as it is called in Israel, has led to record-high infections here with official numbers reaching 48,000 in one day. Since then, the numbers have dipped, but that was after the introduction of home testing for the vaccinated only, which may have led to false negatives or possible underreporting of positive cases.

Nicole Jansezian is the news editor for both ALL ISRAEL NEWS and ALL ARAB NEWS and senior correspondent for ALL ISRAEL NEWS

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