Many researchers are excited about the prospect of nasal vaccines for COVID-19. “Yes with an exclamation point,” says Troy Randall, an immunologist at the University of Alabama at Birmingham, when asked if they’re worth exploring.

In countries like the U.S., where about 76% of people have had at least one dose of the COVID-19 vaccine, nasal vaccines would by default be used primarily as booster shots, and some research teams are studying them specifically in this capacity. But if they’re found to be effective and eventually authorized, they could also give young children and people who fear needles more options.

There’s a long road ahead. While oral vaccines are fairly common, the only nasal vaccine cleared by the U.S. Food and Drug Administration to fight a respiratory pathogen is FluMist, which is used to prevent influenza among people ages 2 to 49. FluMist was in development for decades but was briefly taken off the market due to efficacy issues, which could foreshadow the challenges awaiting vaccine researchers working to create a nasal COVID-19 vaccine.