by An intranasal SARS-CoV-2 vaccine could quickly reach the respiratory tract, where the virus most often causes symptoms. And a spray or drops might be a more pleasant option for people who are afraid of needles. But so far, only a few countries have approved nasal vaccines against COVID. Now researchers report in DHW Nano they have developed one that can fight the original virus and two variants in hamsters.
The current batch of injected COVID vaccines have been effective in combating SARS-CoV-2 infection worldwide. But these injections enter the body in muscle tissue, while the virus enters and causes many of the typical COVID symptoms in the respiratory tract. Therefore, intranasal immunizations with an aerosol or droplet might be a better option. Although India and a couple of other countries have approved intranasal COVID vaccines in recent months, the road to formulating successful intranasal vaccines is not an easy one. For example, AstraZeneca announced this month that its intranasal candidate failed to produce a strong immune response in nasal tissues and offered less systemic protection than the intramuscular version. So Madhavan Nallani, Pierre Vandepapeliere and their colleagues wanted to formulate an intranasal COVID vaccine that would stimulate both a systemic and respiratory tract immune response, and would also work against SARS-CoV-2 variants.
The researchers based their vaccine on the spike protein of the beta variant of SARS-CoV-2, separately encapsulating the antigen and an immunostimulatory adjuvant in nanoparticles known as artificial cell membrane polymerosomes. They packaged the two components separately so they could more easily swap out the tip component for one of another variant if needed. Intramuscular co-administration of the parts produced a strong immune response in both mice and hamsters. However, when hamsters injected with the new vaccine were exposed to the live virus, they developed an infection. In contrast, intranasal coadministration in hamsters produced a strong systemic immune response. It also eliminated viruses from the respiratory tract and prevented lung damage associated with infections. Regardless of how the vaccine was administered, it provided protection against multiple variants, including omicron. Based on these results, the researchers are now recruiting participants for a Phase 1 clinical trial.
The authors acknowledge funding from the National Health Innovation Center Gap Funding Award Singapore.
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