New Delhi: An aerosolised Covid-19 vaccine — one which is inhaled instead of being injected — developed in China has been shown to be safe and to elicit an antibody response in the first reported human trials of such a vaccine, according to a study published Monday in The Lancet Infectious Diseases journal.
So far, all the major Covid-19 vaccines that have been approved for use are intramuscular ones.
In a Phase 1 clinical trial by researchers from CanSino Biologics and Zhongnan Hospital in Wuhan, China, researchers aimed to evaluate the safety and immunogenicity of an aerosolised vaccine in adults without Covid-19.
The vaccine is an adenovirus type-5 vector-based — similar to Convidecia, a single-dose Covid vaccine developed by CanSino Biologics.
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Fever, fatigue and headache the most common reactions
For the trials, participants were enrolled and randomly assigned into five groups to be vaccinated with the intramuscular injection, aerosol inhalation, or both.
The first two groups either received an initial high dose or low dose of the aerosolised Ad5-nCoV vaccine on the first day, followed by a booster on Day 28.
The third group, which was the mixed vaccination group, received an initial intramuscular vaccine on the first day, followed by an aerosolised booster vaccine on Day 28.
The fourth group received one high dose of the intramuscular vaccine. The last group received two low doses of intramuscular vaccine.
Since phase 1 trials are primarily designed to evaluate the safety of the vaccine, the researchers looked for adverse events 7 days after each vaccination.
“To our knowledge, this study is the first to report clinical data for an aerosol COVID-19 vaccine,” the researchers wrote in their study. Along with this, they also evaluated the antibody levels 28 days after the last vaccination.
Between September 28 and 30, 2020, 130 participants were enrolled in the trial and randomly assigned into one of the five groups.
Within 7 days after vaccination, the most common adverse events reported included fever, fatigue, and headache.
Participants who received intramuscular vaccination reported more adverse events than those who received the aerosol vaccine. Importantly, the team detected no serious adverse events within 56 days after the first vaccine.
The team noted that two doses of aerosolised vaccine neutralising antibody responses were similar to one dose of intramuscular injection.
With the safety of the vaccine established, the researchers said now the efficacy and cost-effectiveness of aerosol vaccination will need to be evaluated in future studies.
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