CanSino's one-shot COVID-19 vaccine

The world's first aerosolized inhalable adenovirus type-5 vector-based COVID-19 vaccine (Ad5-nCoV) is progressing well toward obtaining emergency-use approval, and it is expected to be in wide use soon thereafter with proven safety, more robust immune responses, and better effects as a booster, the Global Times learned from the vaccine developer and an industry insider on Wednesday.

Aerosolized inhalable Ad5-nCoV can produce a strong cellular immune response, which maintains the same level as that obtained by traditional intramuscular injections in 14 days.

Besides, the increase of IgG antibodies after inhaling Ad5-nCoV as a booster shot could be seven to eight times that of an inactivated vaccine as a booster, the Global Times learned from the developer CanSinoBIO.

The vaccine was jointly developed by CanSinoBIO and researchers from the Institute of Military Medicine under the Academy of Military Sciences led by Chen Wei. Further clinical trials are ongoing.

Experts recommend the inhaled vaccine as a promising candidate for booster shots of inactivated vaccines.

The phase I clinical trials found that an aerosolized booster vaccination taken 28 days after the first intramuscular injection "induced strong IgG and neutralizing antibody responses," said the report of the trial, which was published in The Lancet Infectious Diseases on Monday. 

The trial also showed that two doses of the aerosol form of Ad5-nCoV were well tolerated, without causing any vaccine-related serious adverse events.

The combination of an inactivated vaccine with inhaled Ad5-nCoV has also been proven to yield highly neutralizing antibodies against the coronavirus prototype, as well as the Alpha, Beta, Gamma and Delta strains, according to the developer.

Animal studies have proven the best enhancement effects of Ad5-nCoV vaccine as a booster shot after two inactivated doses, while the effect of the mRNA vaccine as a booster was second only to that of Ad5-nCoV. 

Inactivated or subunit vaccines were significantly less effective as booster shots than Ad5-nCoV and mRNA vaccines, with a nearly 10-fold difference in antibody levels.

The latest clinical trial results showed good safety results when children aged 6-17 years old were given reduced doses of Ad5-nCoV, and the incidence of adverse reactions was lower than for adults.

If the inhalable Ad5-nCoV is approved for emergency use, it would be the world's first vaccine to achieve triple immunity - humoral, cellular and mucosal - Tao Lina, a Shanghai-based vaccine industry insider, told the Global Times on Wednesday.

The inhalable vaccine can stimulate an immune response in the mucous membranes of a person's respiratory tract. This makes it less painful and more accessible, especially for children and vulnerable people, experts said, as it avoids regional pain and swelling.

What's more, the inhaled form requires only one-fifth of the dosage of an injected one, which preserves more doses and relieves production pressure, according to experts.