Nasal spray vaccines aim to halt respiratory pandemics but face major scientific hurdles
Scientists argue that delivering vaccines through the nose could stop infections at their entry point, yet creating effective mucosal shots remains difficult.
While injectable COVID-19 vaccines dramatically reduced severe disease, they failed to block transmission because they do not protect the nasal and throat surfaces where SARS-CoV-2 initially replicates. Immunologists suggest that nasal administration could generate local immune cells that stop pathogens before they spread. To date, the only approved intranasal vaccine in the West is the live-attenuated FluMist flu spray, used in children to limit community spread.
New programs are testing nasal formulations against pneumonia, pertussis, RSV and COVID-19, but many have stumbled, such as Sanofi's RSV trial halted in 2025 for poor infection prevention. Challenges include eliciting a robust response without causing harmful inflammation, as no adjuvant is yet approved for respiratory use, and translating promising mouse data to humans has proved unreliable. Researchers are exploring novel adjuvant nanocages and live-attenuated virus platforms, but without clear blood-based markers of protection, large, costly trials remain essential.
Why it matters
Nasal vaccines could protect individuals and stop disease spread, offering a tool to prevent future pandemics.
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