"Experts", as in the vast majority of all scientists and physicians with relevant credentials amongst whom there's a near unanimous consensus on their efficacy and safety.
Of course, I bet that astrologers are in near-unanimity about the efficacy of horoscopes!
Not that I think vaccines are either ineffective or unsafe — just that 'these conclusions are accepted by people who accept these premises' is hardly persuasive to those who don't accept those premises.
Scientists/physicians have done the necessary research studies to demonstrate both efficacy and safety. They are, in fact, legally required to do both before their products can even be administered to patients. Studies have been done involving tens of millions of patients, entire diseases have been wiped off the earth, etc.
Meanwhile, astrologers are in possession of plenty of empirical data that it's a bunch of hooey with no evidence supporting its efficacy. (It is, of course, generally regarded as safe.)
