Oxford vaccine 95% effective if given 2-3 months apart: SII

By Rahul Vaimal, Associate Editor
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Oxford University and UK-based AstraZeneca will soon release data showing that if the two shots are separated by around 2-3 months, the efficacy of its COVID-19 vaccine increases to as much as 95 percent, said Adar Poonawalla, chief executive of the Serum Institute of India (SII), which is the manufacturing partner for the vaccine.

“You’ll be hearing some good news from the UK very soon. It would be a 90-95 percent effective vaccine if you just keep a two-to-three months’ gap between dose 1 and dose 2. They will make that public with documentation,” Mr. Poonawalla said at a press conference.

Winning formula

The comments from Mr. Poonawalla follow a remark by AstraZeneca CEO Pascal Soirot that the company has worked out a “winning formula to get efficacy up there with everybody else.” Mr. Soirot, however, did not provide details to support his claim, saying that the data will be released at “some point.”

Efficacy results of AstraZeneca’s vaccine, which it has co-developed with Oxford University, sparked a controversy after it claimed that a dosing error increased the effectiveness of the vaccine. Mr. Soirot had earlier admitted that “We would have preferred a simpler set of results.”

AstraZeneca’s clinical trials for its vaccine in the UK and Brazil included two separate dosing regimens. A lower dosage gave a greater efficacy of 90 percent while two full doses a month apart gave a 62 percent efficacy.

Researchers were unable to explain why the lower dosing regimen, a half dose followed by a full dose one month later, was more effective. Instead, the researchers said they had stumbled upon it by accident and called the superior results “serendipity”.

Serum Institute, the contract manufacturer of the vaccine, conducted its own phase 2 and 3 bridging study in India using two full doses, which showed a 62 percent efficacy in AstraZeneca’s trial. Bridging studies look at safety and immune response to prove that the version being contract manufactured is the same as the original.

Mr. Poonawalla also said the vaccine is expected to get an emergency-use license from the UK Medicines and Healthcare products Regulatory Agency and the Indian regulator by early January.

The Oxford-AstraZeneca vaccine is a more popular option among developing nations due to its price and ease of storage. For instance, the vaccine from American drugmaker Pfizer has to be transported and stored at -70 degree Celsius which is not a very feasible option for the poorer countries of the world.