According to lab studies at the University of Oxford, the third dose of AstraZeneca Plc’s Covid-19 vaccine significantly increased neutralizing antibody levels against Omicron.
The vaccine, developed by Astra and Oxford, increased neutralizing antibodies to levels comparable to those seen after two doses of the Delta variant with a booster shot, the drug company said in a statement Thursday. According to the company, a third dose produced higher levels of neutralizing antibodies than individuals who had recovered naturally from the alpha, beta, and Delta strains.
The findings are largely positive for the vaccine, which has been reduced to the role of a booster in the West after messenger RNA vaccines were shown to be more effective in various trials. The study included 41 people who had received the third dose.
In early London trading, Astra shares were up 0.3%.
Individuals vaccinated with two doses of Astra’s shot retained neutralizing activity against Omicron, despite a 36-fold decrease from the original virus strain, according to data from another lab study.
Because of Omicron’s rapid spread and ability to reduce antibody protection in many vaccines at first, many countries launched accelerated booster campaigns. For the first time, the United Kingdom reported more than 100,000 new Covid cases on Wednesday, exerting pressure on Prime Minister Boris Johnson, who has resisted imposing additional restrictions before Christmas.
Early research from South Africa, Scotland, and England, however, indicates that the highly mutated Omicron variant appears to be less likely to land patients in the hospital than the Delta strain. The findings raise hopes that there will be fewer cases of severe disease; however, due to Omicron’s greater infectiousness, it could still have a significant impact on health services, fueling the need for boosters.
“It is very encouraging to see that current vaccines have the potential to protect against Omicron following a third dose booster,” said John Bell, a professor of medicine at Oxford and one of the study investigators. “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.”
Astra’s findings follow recent studies by Pfizer Inc. and Moderna Inc. on how their vaccines fare against Omicron. Pfizer and partner BioNTech SE preliminary lab tests revealed that the third dose of their Covid-19 vaccine may be required to neutralize Omicron after researchers observed a 25-fold reduction in neutralizing antibodies that fight the variant after two doses.
A booster dose also increased antibody levels against Omicron, according to Moderna.
Novavax Inc. stated on Wednesday that its vaccine induces an effective immune response against the variant, but that an Omicron-targeted vaccine may be needed.