Includes Expert Content
MMR vaccination
flakey posted:
My son is almost 5 he had his first MMR jab age 2, 2nd booster last April and accidentally today the doctor gave him another MMR injection as didn't check his records. Is he safe from this - i'm quite worried.

Roy Benaroch, MD responded:
There is nothing to be especially worried about. An extra dose is not more likely to cause any problems.

There are have been studies of a third dose of MMR for use during outbreaks to provide extra immunity, and some have even suggested routinely using three doses since the rates of measles and mumps are increasing (because of misguided vaccine refusal.) These studies have confirmed that a third dose is no more likely to cause any problems than the second or first doses. One study is summarized here: