Measles, mumps, rubella, and varicella antibodies among international and domestic university students.

BACKGROUND: Vaccine-preventable infections are generally well-controlled in Australia. However, gaps in immunity can lead to outbreaks and are important to identify. Young adults are a highly mobile population and a potential source of imported infections. We aimed to evaluate anti- measles, mumps, rubella and varicella (MMR&V) IgG seroprevalence and explore factors relating to antibody seropositivity.

METHODS: A cross-sectional online survey was conducted among students from a large Australian university to collect demographic, vaccination, infection and travel characteristics. Blood samples were collected to measure MMR&V seroprevalence. Logistic regression was used to identify factors associated with seropositivity.

RESULTS: Among 804 university students, seroprevalence (positive or equivocal) for measles was 82.3% (95% CI 79.6%-84.8%), mumps 79.5% (95% CI 76.7%-82.3%), rubella 91.5% (95% CI 89.6%-93.5%), and varicella 86.2% (95% CI 84.1%-88.8%), with 452 (56.2%, 95% CI 52.8-59.6) seropositive to all four viruses. Varicella seropositivity was highest in the older birth cohort (born 1988-1991). Measles seropositivity was higher for international students compared to domestic students. Among international students, mumps seroprevalence was significantly lower than measles and rubella seroprevalence. International travel in the previous 12 months was reported by 63.1% of students, but only 18.2% of travellers reported seeking pre-travel health advice prior to most recent international travel.

CONCLUSIONS: Overall, this study suggests immunity to MMR&V is sub-optimal. We found the university student population to be highly mobile and unlikely to seek pre-travel advice, thus are a potential source of infection importation. The implementation of university immunisation policies could address the gaps identified and our findings can inform the development of targeted vaccination campaigns.