While most COVID-19 vaccines in development rely on arm injections, leading immunologists argue that nasal delivery could provide superior protection by targeting the virus at its entry point.
Global research into SARS-CoV-2 vaccines presses on. As the New York Times reported on July 14, 2020, the majority of the 150 candidates then in testing required intramuscular arm injections. Yet experts question if this is optimal.
SARS-CoV-2 primarily invades via mucous membranes—the moist tissues lining the nose, mouth, lungs, and digestive tract. These barriers mount a rapid immune response through specialized cells and molecules. Yale University immunologist Akiko Iwasaki emphasizes that nasal vaccines could harness this frontline defense.
Iwasaki highlights how mucosal immunity might curb the virus's rapid spread, attacking it on multiple fronts as it breaches our defenses. In her view, a nasal vaccine could match—or surpass—the efficacy of intramuscular ones.
Without robust mucosal responses, vaccines fall short. Johns Hopkins vaccinologist Anna Durbin notes that sterilizing immunity—eliminating the virus before it infects cells—is more achievable nasally. Intramuscular shots protect against severe disease but leave recipients vulnerable to mild infections and transmission.
Developing nasal vaccines is challenging. Replicating mucosal immunity reliably proves difficult, and targeting these tissues often involves riskier components. Safer options like inactivated virus or genetic material may not trigger strong enough responses. Consequently, effective nasal vaccines could take longer to develop and likely won't lead the market race.
