Omicron, as the most transmissible variant of SARS-CoV-2, is rapidly spreading over the world and has displaced Delta as the dominant strain in a number of regions. Some experts have indicated that mucosal immunization of the respiratory system with an inhaled form of the vaccine may be more efficient in dealing with the Omicron strain in light of recent results that demonstrate Omicron infections are more concentrated in the upper respiratory tract. Several inhalation vaccines for COVID-19 are also on the horizon in the global fight against Omicron, and are expected to become another major weapon.
Omicron possesses more mutant sites and is more contagious than prior strains, with the majority of them residing in the upper respiratory system rather than the lungs.
While the existing intramuscular vaccines on the market today generally have only humoral and cellular immunity, the vaccine given in the arm produces antibodies in the blood, but few antibodies reach our nasopharyngeal mucosa, which, together with the gradual decline in the level of neutralizing antibodies in the body after vaccination, means a weakening of the immune effect, together with the new characteristics (high immune escape, infestation of the upper respiratory tract) arising from the mutation of strains such as Omicron. Therefore, a vaccine booster has become a widely promoted policy after mass vaccination.
Vaccines with mucosal immunological effects are more effective in preventing respiratory viral infections in general, but the inhaled COVID-19 vaccine accesses the respiratory system and lungs through inhalation, triggering triple protection against mucosal, humoral, and cellular immunity. As a result, while dealing with the Omicron strain, the inhalation vaccine becomes a potentially more effective approach.
Multiple studies back this up: Yale immunologist Akiko Iwasaki and her colleagues published a preprinted paper in which they found that a transnasal vaccine booster shot increased the production of strong antibodies and immune memory cells in the respiratory mucosa and improved protection against the initial vaccination in rats. Furthermore, studies published in the internationally renowned medical journal The Lancet found that adverse responses were less common following heterologous boosting with inhaled COVID-19 vaccine than after homologous boosting with the live attenuated vaccine.
The immunogenicity results showed that the peak was attained 28 days after the inhalation booster, and the neutralizing antibody level was significantly higher than that of the live attenuated vaccine homologous booster group, which was 10.7 times higher. There were no serious side effects in the inhalation group 28 days after booster vaccination, and there were no clinically significant lung function abnormalities in the different dose inhalation groups. It is safer, has fewer negative side effects, and is more suited to the elderly and children.
Inhalation vaccine development is also in full swing around the world, with Bharat India and Washington University in St. Louis collaborating on the BBV 154 vaccine, which entered clinical phase III earlier this year and is expected to be one of the world’s fastest inhalation COVID-19 vaccines to hit the market.
