A: Scientists are working on it, but it may be a year or longer before they are available in the U.S. and E.U.
Several groups in the U.S. are working to develop nasal vaccines for COVD-19, but most are still doing pre-clinical trials in animals. Two groups have progressed to studying humans, and one of them reported favorable Phase 1 trials results just last week. So far so good, but Phase 1 trials are done on small groups of people to mainly assess safety and if they work at all. The next step is Phase 2, which looks at safety and dosing. The final research step would be Phase 3, which is a study that enrolls lots of people to measure actual effectiveness of the vaccine as well as safety. Even if all of these studies go well, they take time to do, so it will be a while before a nasal vaccine will be available in the U.S.
Interestingly, there ARE nasal COVID-19 vaccines that have been approved in China, India, Iran, and Russia, but we do not have good access to the data on those (and they are not available in other countries). In the U.K., a Phase 1 trial by AstraZeneca showed disappointing results back in October, so they had to go back to the drawing table. Not everything always pans out in science!
Nasal vaccines are worth pursuing, as they have two main advantages. One is that no shot is needed, which can be great for kids, those who are needle-phobic, and areas of the world without a lot of health care infrastructure. The second is that the immunity that develops from nasal vaccines is often more effective at preventing infection than what you get from injected ones. This is because the immunity develops in the linings of the nose itself, rather than just in the bloodstream.
Think of your body like a castle, with your immune system being soldiers. With an injected vaccine (shot), you develop excellent immunity (trained soldiers) inside the castle walls. Enemies (infection) might get in, but you can usually defeat them before they take over. With a nasal vaccine, however, you have soldiers manning the castle walls (the lining of your nose) and can prevent the enemy from getting inside in the first place! This could be a hugely important tool in controlling COVID-19. Not only would there be fewer overall infections, but there would also be less transmission (spreading) of the virus. That would decrease risk of exposure for high risk folks and help reduce the frequency of new variants.
Bottom line: A nasal vaccine against COVID-19 could be very helpful in many ways, but the U.S. and E.U. likely still have a while to wait.
Stay safe. Stay well.
Those Nerdy Girls
Article about recent Phase 1 study results
Vaccine Development Timeline and Phases
How nasal spray vaccines could change the pandemic, from Nature