Covid: Nasal vaccine key development

The emergency use authorisation for Bharat Biotech’s nasal vaccine INCOVACC for primary immunisation against Covid-19 is considered to be an important step forward in the fight against the pandemic. It is India’s first nasal vaccine and is intended for restricted use in emergencies for the 18-plus age group. The vaccine was developed in partnership with scientists at Washington University and is manufactured by Bharat Biotech. The Government of India partly funded product development and clinical trials. It uses a version of the chimpanzee adenovirus to take the spike protein to the lining of the nose. China has developed a similar vaccine, and INCOVACC is the second such vaccine to get approval, and more are at various stages of development in different countries. The Chinese vaccine is inhaled through the nose and mouth as an aerosolised mist; INCOVACC is administered in the form of nasal drops.

Nasal vaccines that target the membranes that line the nose, mouth and lungs are considered to be more effective than other vaccines. They produce immune responses when the Covid virus enters the body and are thought to be able to prevent even mild cases of illness and block transmission to other people. Other vaccines cannot prevent the transmission of the disease. Nasal vaccines are also cost-effective and are more suited for use in poor and developing countries. They are easy to preserve as they are stable at 2-8 degrees Celsius. INCOVACC is to be used as a two-dose primary inoculation, rather than as a booster. Bharat Biotech has claimed that the vaccine will be a global game changer in intra-nasal vaccine technology.

The company has said that it has finished phase 3 trials with over 3,000 people who received two doses of the nasal vaccine. It also made a booster trial with 875 people who received a single dose as a heterogenous vaccine. It has said that the trials were effective but has not published the data yet. If the vaccines are able to prevent transmission it is a big achievement, but more data is needed to prove this. The advantages of the nasal vaccine should lead to its wide use in the country. There are still large numbers of people who have not gone in for vaccination. But precisely because the nasal vaccine has the potential to be a game changer, it would be better for the regulatory authority and the government to put it through the regular approval process and give it full authorisation rather than the emergency use authorisation given now. It was perhaps unnecessary for the vaccine to be given emergency authorisation at this stage when other vaccines are available and when the World Health Organisation has said that Covid is receding.