Pharmaceutical firm AstraZeneca on Thursday announced that the booster shot of its Covid-19 vaccine significantly increases the level of antibodies against the Omicron variant of the coronavirus disease.

In a statement, the company said that the antibody levels in a person’s body after administering the booster dose were similar to those which the vaccine provided against the Delta variant after two of its doses.

The statement added that the level of antibodies after the booster jab was higher than that of natural antibodies among people who had previously been infected with Covid-19.

However, the study is yet to be peer reviewed.

In the study, blood samples from coronavirus-positive patients who had received a booster shot and those who had reported previous infection from other variants of concern were analysed. It included samples from 41 individuals who had received three doses of Vaxzevria, the version of AstraZeneca vaccine being used in the United Kingdom.

In India, the vaccine is called Covishield, which is being manufactured by Pune-based Serum Institute of India.

Besides AstraZeneca, Pfizer and Moderna too have said that their booster shots were effective against the Omicron variant.

“It is very encouraging to see that current vaccines have the potential to protect against Omicron following a third dose booster,” said Professor Sir John Bell, Regius Professor of Medicine at the University of 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.”

AstraZeneca said it was collecting more evidence on the effectiveness of the vaccine against the Omicron variant and also conducting the trials for a new vaccine.

The new vaccine is being tailored for Omicron, the company had said on Tuesday, according to Reuters.

The Omicron variant, which has a large number of mutations, was first detected in South Africa on November 24. Two days later, the World Health Organization declared it a “variant of concern”.

Omicron has spread to 89 countries as of December 16, according the global health body.

On December 17, the World Health Organization had said that number of cases of the variant is doubling in 1.5 to 3 days in areas with community transmission.