While a fourth dose of COVID-19 vaccine led to an increase in antibodies, it was not enough to protect against infection from the omicron variant, preliminary findings from an Israel-based study suggest.
Researchers presented the early findings during a news conference Jan. 17, CNN reports.
"These are very preliminary results. This is before any publication, but we're giving it out since we understand the urgency of the public to get any information possible about the fourth dose," said Gili Regev-Yochay, MD, director of the infection prevention and control unit at Sheba Medical Center in Israel.
The findings are based on a study involving 274 healthcare workers at Sheba Medical Center who received a fourth dose of either the Pfizer-BioNTech or Moderna mRNA vaccine. There was also a control group who did not receive a fourth dose. The findings showed fourth doses led to a slight boost in antibodies but did not prevent infection from omicron.
"Despite increased antibody levels, the fourth vaccine only offers a partial defense against the virus," Dr. Regev-Yochay said, according to USA Today.. "The vaccines, which were more effective against previous variants, offer less protection versus omicron."
Dr. Regev-Yochay added the current data indicates a fourth vaccine for vulnerable populations makes sense though is "probably not enough to support the decision to give it to all of the population."
On Jan. 4, Israeli Prime Minister Naftali Bennet announced preliminary findings showing people who received a fourth dose of Pfizer's vaccine had a fivefold increase in antibodies a week later. The latest findings are based on additional analysis.
Israel became the first country to broadly roll out fourth doses for healthcare workers and people 60 and older Jan. 2.