A nasal spray Covid-19 vaccine co-developed by Hong Kong microbiologist Professor Yuen Kwok-yung and his team with a mainland China university and pharmaceutical firm has been approved for emergency use by the national authorities.
The intranasal vaccine DelNS1 from Hong Kong University, Xiamen University and Beijing Wantai Biological has been approved in mainland China. This is the second vaccine approved in China after CanSino’s inhaled vaccine. China is aiming to speed up vaccinations in the elderly people aiming to ease unpopular zero-COVID curbs given that booster uptake in those over 80 years old is ~40%.
DelNS1 uses the influenza vector to express SARS-CoV-2 receptor binding domain proteins. The vaccine will be delivered by syringe with a special tip designed to produce a mist.
Currently, five intranasal/inhaled vaccines have been approved worldwide. CanSino and DelNS1 in China, Bharat in India, Razi Cov Pars in Iran, and Sputnik V in Russia, however, there are no such vaccines approved in Western market.
The developers mentioned in a media article that DelNS1 is 80% effective against Omicron infection in participants previously vaccinated with an inactivated vaccine, and 55% effective in the unvaccinated population. However, published data from their phase III trials is not yet available.
Intranasal vaccines can offer several advantages including ease of administration, logistical benefits, and generation of immunity at the site of infection (mucosal immunity) on top of systemic immunity, which could increase efficacy against infection.
It is hoped intranasal vaccines will increase protection against infection and transmission by inducing an immune response in the mucosa, however, data for such a response is lacking for most, and even in the approved, candidates. Codagenix and AstraZeneca found their intranasal vaccines induced mucosal IgA antibodies in less than 50% of participants, as a primary series and/or booster, in phase I trials.