of course there was a reason. probably multiple.

what antivax people don't understand is that vaccines are extremely well understood, especially boosters for vaccines which have already been through testing.

it's not like a vaccine for a new virus is 100% experiment, or even 1%. a vaccine is like a Rubik's cube; a known thing which you hope is in the right configuration to do its job. if it's in the wrong configuration then you're basically vaccinated against nothing or you are vaccinated against something you didn't need a vaccine for.

once you've built a few million Rubik's cubes you can stop doing human testing and quality control on every single one of them.

like Rubik's cubes, vaccines are made from known and understood ingredients, each with known and understood behaviors.

vaccines are inert to every part of a human body, except the immune system, by design.

vaccines are not an unknown thing, which could be made from any random junk on the shelf, and which may or may not kill you; vaccines are safe.

the amount of scare-tactic half-truth coming from antivaxxers is nuts because they are just repeating stuff they've heard that they don't understand but that sounds super bad on the surface, and then letting their fear override everything else then repeating the half-truth to the next person.

Yes? Because trials would make the formulation less timely, and therefore less efficacious.

They've done this on the flu shot for YEARS.

Or are you implying that a reason for fast tracking must necessarily be nefarious?

The big reason is to make it available before the fall, when people spend more time indoors and spread it more. Also you don't really need to test it, it's known to be safer than the disease.