New study: Pfizer COVID-19 booster protects against Omicron

The findings were similar to those presented by BioNTech and Pfizer earlier in the week, which were an early signal that booster shots could be key to protect against infection from the newly identified variant.

The study, carried out by Sheba Medical Center and the Health Ministry's Central Virology Laboratory, compared the blood of 20 people who had received two vaccine doses 5-6 months earlier to the same number of individuals who had received a booster a month before.

"People who received the second dose 5 or 6 months ago do not have any neutralization ability against the Omicron. While they do have some against the Delta (strain)," Gili Regev-Yochay, director of the Infectious Diseases Unit at Sheba, told reporters.

"The good news is that with the booster dose it increases about a hundred fold. There is a significant protection of the booster dose. It is lower than the neutralization ability against the Delta, about four times lower," she said.

The Israeli team said they worked with the actual virus while the companies used what is known as a pseudovirus, which was bio-engineered to have the hallmark mutations of Omicron.