Bharat Biotech seeks nod for phase-3 clinical trials of nasal vaccine

Covaxin maker Bharat Biotech has sought approval to start phase-3 clinical trials for its intranasal Covid-19 vaccine candidate BBV154 from India’s drug regulator. The company plans to administer the nasal vaccine as a booster dose for those who have already received two shots of any Covid vaccine, sources revealed.

A company source said, “We have submitted a phase 3 clinical trial application to DCGI. An intranasal vaccine as a booster dose will be easier to administer in mass vaccination campaigns. Intranasal vaccines have the potential to prevent transmission.”

Details about the size of the phase 3 clinical trial are not yet known.

The Hyderabad-based vaccine maker conducted phase 2 trials on 650 volunteers, whose recruitment was completed by September. The first phase had 175 participants.

It had conducted a three-legged phase 2 clinical trial for its intra-nasal vaccine, which was tested in three combinations — two intranasal shots, first a Covaxin shot followed by the nasal vaccine, or a Covaxin shot following a nasal one.

The idea was to see which combination induced better and long-lasting immune response. Therefore, the intranasal vaccine could be used as a combination with the intramuscular Covaxin shot. The two vaccines have different mechanisms of action, and trigger slightly different immune responses.

Shahid Jameel, a senior research fellow at Green Templeton College at the Oxford University, had told Business Standard earlier, that a different kind of antibodies protect the nasal mucosa - these are called IgA antibodies. "This is not sufficiently generated when a vaccine is administered through the intramuscular route," Jameel said.

Commenting on the nasal vaccine, Jacob John, the former head of Centre for Advanced Research in Virology at the Indian Council of Medical Research (ICMR), said that to have nasal vaccine was a 'fantastic idea' for two reasons - one it can potentially create sterile immunity (the nasal mucosa is sterile. When the pathogen comes in contact with the nasal mucosa it has antibodies to neutralise the pathogen) and secondly, it is easy to administer and thus scalable.

Experts feel that when one gets sterile immunity in the nasal tract, one does not shed the virus, which prevents transmission.