Stephanie Longet, Stéphane Paul
The COVID-19 pandemic has accelerated the development of intranasal and inhaled COVID-19. vaccines. Four vector-based and one adjuvanted protein-based vaccines have been licenced. They have been shown to be safe. However, their ability to induce strong protective mucosal immunity in humans remains to be improved. Diversifying intranasal vaccine platforms, improving the delivery of vaccine components and determining mucosal correlates of protection could help in optimizing intranasal COVID-19 vaccine efficacy.