I2. Pediatric Vaccines
Background : Numerous mumps outbreaks occurred in the United States over the last decade, with outbreaks affecting young adults on college campuses being among the largest and most widely publicized. However, at least half of mumps cases and outbreaks occurred in other age-groups and settings. We describe reported mumps cases among children and adolescents during 2015 through 2017.
Methods : The Centers for Disease Control and Prevention (CDC) analyzed reports of confirmed and probable mumps cases in persons aged ≤18 years (defined here as pediatric mumps) transmitted electronically through the Nationally Notifiable Diseases Surveillance System (NNDSS) by the 52 reporting jurisdictions.
Results : Between January 1, 2015–December 31, 2017, 49 jurisdictions reported 4,886 pediatric mumps cases (35% of all US reported cases, 13,807); 8 jurisdictions reported >100 cases each, representing 82% of all pediatric cases. Overall, 29 (1%) cases were in infants <1 yr, 406 (8%) were in children aged 1–4 yrs, 1,408 (29%) in children aged 5–10yrs, 1,365 (28%) in adolescents aged 11–14yrs, and 1,678 (34%) in adolescents aged 15–18yrs. Most (3,548, 73%) cases did not travel outside the state during their exposure period; only 37 (1%) traveled outside the country. Cases in patients aged 1–4 yr were more frequently non-outbreak associated (38%) than those in patients <1 yr and 5–18 yrs (24% and 9%, respectively). Among 3,309 (68%) patients with known number of MMR doses received, 81% of those 5–18 yrs had ≥2 MMR doses, while 67% of those 1–4 yrs had ≥1 dose. Median time since last MMR dose for patients with 2 doses was 8 years (IQR: 4, 11 years). Four patients had meningitis and 1 had encephalitis; all were ≥10 years old and previously received 2 MMR doses. Of male mumps patients older than 10 years of age (2,113), 46 (2%) reported having orchitis; of these, 33 (72%) had 2 MMR doses. Sixty-four patients were hospitalized and there were no deaths.
Conclusion : About one-third of cases reported during the recent US mumps resurgence were in children and adolescents. The low rate of mumps complications compared with previous studies suggests mumps complications may not be adequately captured in national surveillance or identified by providers. Providers should remain vigilant that mumps can still occur among fully vaccinated pediatric patients, even those recently vaccinated.