Many of us think that mumps is a disease that has gone away. It rarely comes up in the differential diagnosis. But should we be re-thinking this?
This week, Pediatrics is early releasing an article by Leah Shepersky and colleagues at the Centers for Disease Control (CDC) that describes the current epidemiology of mumps in the US. The article is entitled, “Mumps in Vaccinated Children and Adolescents: 2007-2019” (10.1542/peds.2021-051873).
Remember that mumps is a reportable disease, so all cases are reported by US health departments to the National Notifiable Diseases Surveillance System. The authors analyzed the data from 2007 to 2019 for all pediatric (0-18 years) mumps cases.
A few takeaways from this analysis:
- There has been a >99% reduction in mumps cases since the introduction of mumps vaccination.
- The age group with the highest incidence is college-aged adults. In those younger than 18 years, the majority of cases of mumps are in older children and adolescents (11-17 years).
- Very few (2%) of cases are associated with international travel or with recent immigration to the US.
- Complications are rare (1%), with orchitis and deafness being the most commonly occurring complications.
What should we conclude from this analysis? The data imply that, although the incidence has dramatically decreased, mumps hasn’t gone away. There is likely a waning of vaccine-induced immunity with time, given the high proportion of disease in older children, adolescents, and young adults. Given that, among those >1 year of age who develop mumps and for whom vaccination status is known, 84% are up-to-date on their MMR vaccine, it is also possible that there are circulating mumps strains that are not included in the MMR vaccine. In an invited commentary (10.1542/peds.2021-052761), Dr. Charles Grose from the University of Iowa suggests that a third dose of mumps vaccine – or maybe using a different version of mumps vaccine (that includes a different mumps virus strain) are potential approaches to managing these mumps outbreaks.
Currently, there is no CDC recommendation for a third dose of mumps vaccine. However, it will be important to continue disease surveillance to determine if this is needed in the future.
I encourage you to read the entire article and commentary. There are details about the epidemiology of this disease that you will want to learn. It will also remind you that mumps hasn’t gone away, and it’s something that you should consider in your differential diagnosis for a child with parotitis, orchitis, or hearing loss.