Good advice from both Posters.
I have only given my horses strangles vaccines once in my entire life and my horse that is drug sensitive got really sick from the shot --- sick as in the vet had to come back out
The intranasal hadn't been developed back then.
The only reason the vet hesitatingly suggested the vaccine was because the Amish community had had a handful of horses die from strangles, wouldn't call the vet, just let the horses die their own death, then buried the horses on their property.
Nothing the law could do either.
For my part, I wouldn't give strangles vaccines again, not even if my closest neighbor ended up with an outbreak. My horses were vaccinated "back then", so I'll take my chances