A biotechnology company in Finland has developed an antiviral nasal spray called TriSb92, which has shown promise in preventing COVID-19 infection as well as treating it if used within four hours after infection inside the nose. The treatment, which works by blocking the virus, appears effective against all variants of concern, including the Omicron variants BA.5, XBB, and BQ.1.1. TriSb92 targets a stable site on the spike protein of the virus that is not known to mutate, making it potentially effective against future variants as well. The treatment could offer an alternative to people who cannot or do not respond to a vaccine, including elderly people and individuals who are immunodeficient for various reasons. The antiviral, however, requires multiple doses per day compared to a single dose of a nasal vaccine that may protect for months.
TriSb92 is one of multiple nasal spray approaches but is unlikely to be as durable as effective nasal vaccines. Many laboratories are shifting from treatments using monoclonal antibodies to treatments using smaller antibody fragments called "nanobodies" because they are more cost-effective and are able to last longer in storage. Several of these nanobodies have shown promise against viruses in cell culture or animal models, including as an intranasal preventive treatment for SARS-CoV-2. These nanobodies and TriSb92 target a specific part of the coronavirus spike protein called the receptor-binding domain (RBD).
TriSb92 is currently in early development, and the company is working to secure funding for clinical trials of TriSb92 in humans. The study was published online in Nature Communications.