Can Bharat Biotech's intranasal vaccine prevent COVID-19 infection and transmission? 

The existing COVID-19 vaccines largely only address the risk of severe disease and death.

However, most experts say it is crucial that the vaccine is as effective in practice as it claims to be in theory. The scientific data for the vaccine is not available in the public domain yet.

When contacted, Bharat Biotech said that data from the late-stage human clinical trials have been submitted for approval to the regulator Central Drugs Standard Control Organisation and will be released publicly later.

Clinical trials

The Hyderabad-based vaccine maker has said that two separate and simultaneous clinical trials were conducted – one to evaluate the intranasal vaccine as a primary dose schedule; and the second trial as a heterologous booster dose for subjects who have previously received two doses of the two commonly administered Covid-19 vaccines (Covishield and Covaxin) in India.

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While primary dose schedule phase III trials were conducted for safety and immunogenicity in about 3,100 subjects in 14 trial sites, heterologous booster dose studies were conducted for safety and immunogenicity in nearly 875 subjects at nine trial sites across India.

Promising premise

Dr V K Paul, member (health), Niti Aayog and head of the country’s Covid-19 task force in the past, has said that the intranasal vaccine requires minimal training to administer, does not need a needle and syringe and is logistically easier to administer.

Paul and others in the government have said on many occasions that the nasal spray vaccines are also likely to prevent the virus from gaining a foothold in the body at an early stage of the infection, something that most COVID-19 vaccines available as of now are not very good at.

‘Antibodies in nose’

Senior virologist Dr Shahid Jameel, who is associated with the University of Oxford and Ashoka University, said that the intranasal vaccine would in theory produce antibodies at mucosal surfaces like nasal epithelium and the respiratory tract.

This would neutralise incoming viruses early on compared with injectable vaccines that give systemic immunity, he said.

The trick, according to Jameel, is to optimise the dose so that the immune system is triggered and not desensitised.

“The latter is a protection to prevent overwhelming of the immune system. We breathe in many things but don’t make antibodies to all; so unless the data is available on the Bharat Biotech vaccine it’s hard to comment on it,” he said.

Immunologist Dr Dipyaman Ganguly from the Council for Scientific & Industrial Research- Indian Institute for Chemical Biology, too, said that intranasal vaccines are expected to be more efficient in reducing transmission apart from providing similar protection against severity as the vaccines currently in use.

“But definitely data on such efficacies derived from randomised clinical trials should be provided to the peers, regulators and the public,” he said.

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Breakthrough vaccine?

Dr Gopi Krishna Yedlapati, consultant interventional pulmonologist with Yashoda Hospitals in Hyderabad, said that an intranasal vaccine may be welcome in view of the rising infections currently.

However, it needs to be seen whether the vaccine is a breakthrough one as an intranasal vaccine against Swine Flu was not found to be very successful, he said.

According to Yedalapati, the advantage of the vaccine may be its high absorption and convenience of administration for kids as well as the elderly.