very simple. they should post name of vaccine in bold at vaccination center. if pfizer, 2 doses apart in 21 days. if moderna, 2 doses apart in 28 days. if j&j, only 1 dose. nurses can’t get it wrong as they need to know which vaccine they are administering in order to use the right dosage and needles. and they need to give you the 2nd appointment if you have a 2-dose regimen. administering various vaccines in the same vaccination center will only confuse everybody and is a no-no. one type of vaccine per vaccination center is the safest way to reduce mistakes and eliminate confusion. if they give you sinovac fuck them hard as it is not approved yet.