Australian vaccine preventable disease epidemiological review series: mumps, 2013-2021

Mumps is a highly contagious acute viral disease. We describe Australian mumps epidemiology, 2013-2021.

National mumps notification, hospitalisation and death data were analysed by age group, Indigenous status, state/territory and vaccination status.

There were 3,643 mumps notifications between 2013-2021 (average annual rate 1.65 per 100,000 population), with highest annual rates 2015-2018 (2.71-3.32 per 100,000 population). Average annual rates per 100,000 population for 2013-2021 and 2015-2018 were highest in the Northern Territory (15.8 and 35.2), Western Australia (4.7 and 9.5) and Queensland (2.6 and 5.0). Average annual rates per 100,000 population were higher in Indigenous people than other Australians in 2013-2021 (25.65 vs 0.82) and 2015-2018 (57.53 vs 1.10). Highest age-specific average annual rates per 100,000 population were in adolescents aged 10-19 years (overall 3.66, Indigenous 48.24 for 2013-2021; 7.60 and 108.52 for 2015-2018), followed by adults aged 20-29 years. Among mumps notifications with vaccination status recorded (n = 2,295 notifications), 64.2% had received ≥ 2 doses of mumps-containing vaccine and 18.1% had received one dose, with 17.7% unvaccinated. Between 2013-2021, 719 hospitalisations had mumps recorded as principal diagnosis (average annual rate, 0.34 per 100,000 population). There were 1-5 deaths coded with mumps as underlying cause of death.

Mumps epidemiology was dominated by large outbreaks predominantly in fully vaccinated Indigenous adolescents/young adults. Mumps outbreaks among highly vaccinated adolescent/young adult populations have occurred overseas related to waning of vaccine-induced immunity, reduced boosting from wild-type virus circulation and high force of infection in close contact settings. A third dose of mumps-containing vaccine is not warranted routinely, but should be considered in the context of outbreaks occurring in high two-dose coverage settings.