Have we come up with a cure for the common cold? How about flu shots every year? The cold and flu strains are getting stronger and mutating and we are not. I got a flu shot once and was immediately sick, haven't had a flu shot in over 10 years now and although I have gotten the flu in that time, it's not on a yearly basis like others at my work place.
To be fair, a cold or flu is a virus, not a parasite. Your body has specific measures for writing into your immune system the instructions to eliminate the threat of that particular virus in the future, if you survive it this time. All a vaccine does is add that immunity without your body having to do it. Viruses mutate continuously no matter the method of immunity. A mite is quite a bit different. Occasional side effects of immunization do include getting sick. Everybody gets to be the 1% of something eventually.