The shortened dosing pattern of the Covid-19 vaccine candidate from the AstraZeneca-Oxford University combine has ended up raising several questions from the scientific community. An interim analysis shared just days ago on the AZ-Oxford vaccine revealed that they had given a shortened half-a-dose first, followed by a second full dose to trial participants. And this achieved greater efficacy, than two full doses.

While an AZ representative called it “serendipity”, it has triggered off queries on whether the protocol has since been changed on the clinical trial and whether it would require changes at the production level as well.

At the global media interaction on the interim analysis, the rationale for the shortened dosing was not explained, except to say that it was seen to work better and more work needed to be done. But in subsequent interactions, company officials reportedly clarified that a manufacturing error had resulted in the changed dosing.

Little clarity

Serum Institute has an alliance with the AZ-Oxford combine on the vaccine and is undertaking clinical trials here. However, there is little clarity from Serum Institute and the Indian drug regulatory authority on whether the shortened vaccine dose would change trial protocols and the production pattern in India. Business Line has reached out to the company and the regulator, a response is awaited.

Epidemiologist and health systems expert Dr Chandrakant Lahariya explains that serendipity is a seen in science, where an inadvertent development happens, and it happens for the better. “The important part is that it is not harmful,” he says, citing the discovery of penicillin, famously described as serendipitous. Dr Lahariya is co-author of “Till We Win: India’s fight against Covid-19 pandemic”, along with Dr Gagandeep Kang and Dr Randeep Guleria.

Efficacy and protocols are two different things, he says, adding that regulatory authorities would be looking into it. “Safety is a concern for Government, regulators and manufacturers,” he says, pointing out that companies would not risk hiding a problem as it could expose them to massive litigation if something goes wrong when large numbers are vaccinated.

Letter to PM

Questions on the AZ-Oxford vaccine come even as health experts in India have written to Prime Minister Modi, urging him to be “very selective” in the immunisation of people using the Covid-19 vaccine, when there is one. This coronavirus infection, like others caused by the same virus family, can be managed through medication, they point out, raising concerns over the many variables that exist in Covid-vaccines.

“Efficacy data has not been presented through peer reviewed article in any medical journal of repute but through press releases. The released data does not provide any differentiation between ages, sex, geographies, co-morbidities, body mass index, antibodies status prior to trial and after testing positive. Therefore, the efficacy of these vaccine candidates for the entire range of human beings is still to be established,” the letter said.

Pointing to new-tech m-RNA vaccines from Pfizer and Moderna, it said, “Some of the companies have used mRNA technology to develop a vaccine. This RNA is being created through use of genetic engineering. Gene based technology have been used for developing vaccine earlier but none for vaccine of any human illnesses so far. What could be its long term effects on human body are uncertain.” The funds used to procure these vaccines should be put into public health infrastructure that benefits more people, it added.