Serendipity and science aside, AZ-Oxford to evaluate ‘shortened’ dosing regimen on Covid-19 vaccine candidate

As concerns are raised over the shortened dosing pattern of the Covid-19 vaccine candidate from the AstraZeneca-OxfordUniversity combine, AZ has clarified that it would evaluate the dosing regimen that, in fact, served-up a better outcome on the vaccine.

“Now that we’ve found what looks like a better efficacy we have to validate this. The specific details for how this evaluation will be done has not yet been finalised,”AZ said in a response to BusinessLine.

In India, Serum Institute is in alliance with the AZ-Oxford combine for the vaccine and is undertaking clinical trials here. The vaccine-maker clarified, India trials were running “smoothly” and in “strict adherence” to protocols.

Dosing regimen

The source of the “shortened dose” controversy lies in details shared recently on the vaccine, where it was revealed that trial participants had been given half a dose first, followed by a second full dose. And, this achieved greater efficacy, than two full doses.

Though an AZ representative called it “serendipity”, international scientific circles have not stopped buzzing on the impact of this development and whether it could delay or change protocol and production plans on this vaccine, in other countries as well. “As we communicated earlier this week, there is strong merit in continuing to further investigate the half-dose/ full dose regimen. We are further evaluating the data and will work with regulators on the best approach for further evaluation. This would add to data from existing trials which are currently being prepared for regulatory submission,” AZ said.

During the earlier global media interaction to share their interim analysis, AZ-Oxford representatives did not explain the rationale for the shortened dosing, except to say that it was seen to work better and more work needed to be done.

In subsequent interactions, though, company officials reportedly said that a manufacturing error had resulted in the changed dosing.

Patience, not panic

Responding to the development, Serum Institute said, “So far, there are no concerns. However, we are going through the data that is available and will make further statement, if needed."

“The AstraZeneca-Oxford vaccine is safe and effective. Even the lowest efficacy results are at 60-70 percent, making it a viable vaccine against the virus. That said, varied age groups with different dosage forms will result in slight variations and efficacy. We must be patient and not panic,” it added.

A representative with the Indian drug regulator added that nothing changes, as serum trials are on the approved two-dose regimen.

It would be reviewed if the trial protocol was changed in the UK and other global trials, the source said.

Serendipity and science

Epidemiologist and health systems expert Chandrakant Lahariya explains that serendipity is seen in science, where an inadvertent development happens, and happens for the better. The important part is that it is not harmful, he says, citing the discovery of penicillin, famously described as serendipitous. Lahariya is co-author of “Till We Win: India’s fight against Covid-19 pandemic”, along with Gagandeep Kang and Randeep Guleria. While efficacy and protocols are two different things, watched-over by regulators, “Safety is a concern for Government, regulators and manufacturers,” he said. It could, for example, expose companies to massive litigation if something went wrong when large numbers are vaccinated.