In the review there were 47 studies, describing 50 outbreaks and at least 54,300 mumps cases.
The highest proportion of mumps cases was among those vaccinated with the Rubini strain and the lowest was among those vaccinated with the Urabe strain. With the exception of one outbreak, the percentages of mumps cases were lower in those vaccinated with two doses of vaccine.
Vaccine effectiveness after one dose (23 studies) ranged from 73% to 91% for the Jeryl Lynn strain vaccine, 54% to 93% for the Urabe strain vaccine, and from -55% to 40% for the Rubini strain vaccine. The effectiveness of two doses (3 studies) was higher than one dose, but no statistical differences were reported.
Four studies reported that the time since vaccination was not associated with an increased risk of disease, and three studies reported that participants who were vaccinated more than five years before an outbreak were at increased risk of developing disease.
Mean rates of primary vaccine failure did not significantly differ for the Jeryl Lynn, RIT-4385, Urabe, and L-Zagreb vaccine strains (range: 5% to 9%).