Fourth Dose of Pfizer-BioNTech Vaccine Only Gives Partial Defense Against Omicron, Israeli Study Suggests

In December 2021, Israel became the first country to roll out the fourth dose of Pfizer-BioNTech COVID-19 vaccine shots. Their move was followed by other countries, including Chile and Denmark, who also announced plans to administer extra doses for their citizens.

However, researchers of the Israeli study found that the fourth dose provided insufficient protection against the Omicron COVID-19 variant after two weeks since the start of the trial on 154 medical personnel at the Sheba Medical Center in Tel Aviv.

Israelis Receive Their Fourth Dose of COVID-19 Vaccine

Amid the surge of COVID-19 cases in Israel, the country's health ministry started giving out the fourth dose of the vaccine. According to Associated Press, it was administered to over 500,000 people last month to those immunocompromised residents, people aged 60 and above, and healthcare workers.

The government hopes that the booster shots will prevent a wave of Omicron variant cases since the country has 250,000 active COVID-19 cases and 8,298 deaths since the pandemic started. However, only 317 of them are reported to be severely ill, fewer than the reported cases of other variants.

Israel Prime Minister Naftali Bennett said in a statement that the trailblazing vaccine campaign of Israel had reached another milestone, with half a million residents have already received the fourth dose.

Gili Regev-Yochay, Sheba Medical Center's director and the lead author of the study, said that the decision to roll out the fourth dose of COVID-19 vaccine to the most vulnerable people in Israel is a good choice. However, the findings of a recent study did not support a wider rollout to the whole population of Israel.

Fourth Dose Does Not Provide Sufficient Protection Against Omicron

Almost a month since the Sheba Medical Center launched a landmark study on the fourth dose in Israel, the hospital recently announced that this fourth booster only gave residents partial protection against the Omicron variant, Times of Israel reported.

Professor Regev-Yocha said that the vaccine was very effective against previous strains but is less effective against the Omicron variant as many people got infected even after receiving the fourth dose. Although, analyses showed an increase in antibodies compared to the third dose.

"The bottom line is that the vaccine is excellent against the Alpha and Delta [variants], for Omicron it's not good enough," she said as Times of Israel reported.

For now, the team has not released more specific data from the trial or given further comments on the effectiveness of the fourth dose against hospitalizations or Omicron-related deaths. Forbes reported that it is also the only study so far that has come out on the fourth dose's effects. Also, these are just preliminary findings that have not yet been peer-reviewed.

Regev-Yochay told reporters that the increase in antibodies from the fourth dose is not enough to protect against the Omicron variant, suggesting that the level of antibodies needed is too high.

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