AstraZeneca’s booster dose of the Covid-19 vaccine and an antibody combination therapy Evusheld (tixagevimab/cilgavimab) effectively prevented infection with the Omicron variant, studies showed.
The research team of University College Oxford, U.K., and Washington University School of Medicine, St. Louis, U.S., posted the virus neutralization data of the AZ vaccine’s booster shot and antibody cocktail on bioRxiv, a preprint server.
According to the research team of Oxford University, the neutralizing titer against Omicron increased significantly after a third dose of the AZ’s Covid-19 vaccine, compared to that after a second dose.
The neutralizing potency was stronger in people with a booster shot than those who recovered naturally from Covid-19 infection (with the Alpha, Beta, Delta, or the original virus).
Sera collected one month after a third dose of the vaccine showed that the third shot neutralized the Omicron variant at a similar level observed one month after a second dose against the Delta variant.
Professor John Bell at the University of Oxford and one of the study investigators said, “It is very encouraging to see that current vaccines have the potential to protect against Omicron following a third dose booster.”
“These results support the use of third dose boosters as part of national vaccine strategies, especially to limit the spread of variants of concern, including Omicron.”
Also, another data from both University of Oxford and Washington University showed that Evusheld, a long-acting antibody combination for preventing Covid-19, retained neutralization activity against Omicron.
Evusheld combines two long-acting antibodies tixagevimab and cilgavimab derived from B-cells donated by convalescent patients after Covid-19 infection.
Vanderbilt University Medical Center in the U.K. discovered it and licensed it out to AZ, which upgraded the drug with a half-life extension.
On Dec. 8, AZ obtained FDA approval for Evusheld to prevent Covid-19 in people who experienced serious adverse reactions of a Covid-19 vaccine or who are immune-compromised due to medical conditions.
Evusheld’s inhibitory concentration 50 (IC50), which gauges neutralizing power, was 273 ng/ml and 147 ng/ml in the Oxford and Washington University studies, respectively, according to AZ.
These figures are within the range of neutralizing antibody titers found in people who have recovered from Covid-19 naturally, the company said.
The findings are in line with pseudovirus neutralizing data from independent investigators at the FDA announced on Dec. 16 and support evidence that Evusheld retains activity against all Covid-19 variants, the company added.