Omicron "Boost": Proof of Concept for a Transmission-Blocking COVID-19 Vaccine?

Lye McKinnon of the University of Manitoba in Canada together with Ali Ssetaala of the Uganda Virus Research Institute in Uganda will determine whether nasal mucosal immune responses induced by COVID-19 vaccines and natural infection can help prevent infection and transmission. Although COVID-19 mRNA vaccines effectively prevent severe disease, they are less effective at preventing transmission, which is critical for protecting vulnerable populations particularly against emerging, highly transmissible variants. Boosting nasal immunity may locally inhibit replication of the SARS-CoV-2 virus and thereby limit both infection and transmission. To test this, they will perform a two-site longitudinal study in Winnipeg, Canada and Kampala/Entebbe, Uganda of fully vaccinated individuals with and without breakthrough Omicron infections to determine whether existing nasal immunity is protective. They will also test whether Omicron breakthrough boosts virus-specific IgA and T cell responses in the nasal mucosa, which may further protect against transmission. The results may strengthen the case for nasal-delivered vaccines to better contain the COVID-19 pandemic.