When can a child with mumps safely return to school, including required exclusion duration and afebrile period?

School Exclusion for Mumps

Children with mumps should be excluded from school for 5 days after the onset of parotitis (parotid gland swelling), regardless of fever status. 1, 2

Isolation Duration and Return-to-School Criteria

• The standard exclusion period is 5 days from parotitis onset, which represents the updated guidance from CDC, AAP, and HICPAC that replaced the older 9-day recommendation. 1, 2

• No specific afebrile period is required for return to school—the 5-day isolation period is the sole criterion, as transmission risk is based on viral shedding patterns rather than fever status. 1, 2

• The change from 9 to 5 days was based on evidence showing that although mumps virus can be isolated from 7 days before through 8 days after parotitis onset, the highest viral loads and transmission risk occur closest to parotitis onset and decrease rapidly thereafter. 2

• Compliance data from university outbreaks demonstrated that students told to isolate for 1-4 days achieved 86% compliance versus only 65% for 9-day isolation, supporting the practical benefit of the shorter 5-day period. 3

Special Circumstances: Outbreak Settings

During school-based mumps outbreaks, different rules apply to susceptible (unvaccinated or incompletely vaccinated) students versus those with active disease:

Students with Active Mumps

• Exclude for 5 days after parotitis onset, as described above. 1, 2

Susceptible Students During Outbreaks

• Unvaccinated or incompletely vaccinated students should be excluded until 26 days after the onset of parotitis in the last person with mumps in the affected school. 4

• Excluded susceptible students can be readmitted immediately after receiving MMR vaccination, without waiting for the full 26-day period. 4, 5

• This extended exclusion for susceptible students is necessary because the incubation period for mumps is most commonly 16-18 days, and surveillance must extend through two full incubation periods (5-6 weeks) to ensure outbreak control. 5

Important Clinical Caveats

• Transmission can occur before symptoms appear: Patients are contagious from 7 days before through 8 days after parotitis onset, meaning transmission often occurs during the prodromal phase or from asymptomatic infections. 6, 2

• Not all mumps cases present with parotitis: Only 30-40% of mumps infections produce typical acute parotitis, while 15-20% are asymptomatic and up to 50% present with nonspecific or respiratory symptoms. 6

• Droplet precautions are required: During the 5-day isolation period, implement droplet precautions with standard precautions, gown, and gloves for all patient contact. 5

• Vaccine failure can occur: Recent outbreaks have occurred in populations with >90% two-dose MMR coverage, indicating that even fully vaccinated students can contract and transmit mumps due to waning immunity or primary vaccine failure. 5, 7, 8