system
Given the following post, respond as if you're commenting on Reddit:
human
Why can't adenovirus-vectored vaccines be aerosolized so they don't require needles?

Whether through a nasal spray or inhalation, it seems like there would be less vaccine hesitancy if there was a route of administration that didn't require needles.
gpt
A couple of reasons: shots are cheaper (nebulizers for delivery cost more), shots are quicker (seconds, versus a couple of minutes to inhale), dosing is consistent with shots more so than inhalation, and, finally, the vaccine can be irritating — which is not a big deal for a muscle, but in lungs it can trigger asthma attacks or breathing problems.

You can’t use a system like an asthma inhaler that delivers albuterol. Those make much smaller particles by forcing the liquid through an aperture under pressure, but if you tried that with the adenovirus, you’d just rip it to shreds in the process.