Can Someone Who Contracts Measles After Age 5 Develop SSPE?
Yes, individuals who contract measles after age 5 can absolutely develop SSPE, and the claim that measles after age 5 carries negligible risk is definitively false. 1
Risk Across All Ages
While the highest risk occurs in children who contract measles before age 5, SSPE can develop following measles infection at any age:
The Advisory Committee on Immunization Practices (ACIP) explicitly states that measles vaccination remains the only effective prevention strategy regardless of age at infection. 1
SSPE occurs in approximately 4-11 per 100,000 measles-infected individuals overall, demonstrating that risk exists across the entire infected population. 1
The typical onset of SSPE symptoms occurs 5-15 years of age, with presentation generally 6-8 years after the initial measles infection—meaning many of these patients contracted measles well after infancy. 1
Age-Related Risk Patterns
The evidence shows a gradient of risk rather than an absolute cutoff:
Children who contract measles under age 5 (particularly under age 2) have the highest risk of developing SSPE. 2, 3
However, adult-onset SSPE cases have been documented in patients presenting at ages 20-35 years, with measles-to-SSPE intervals ranging from 14-22 years, demonstrating that infection at older ages (after 9 years) can still lead to SSPE. 4
The literature documents SSPE cases following measles infection acquired at various ages throughout childhood and even into adolescence. 5, 6
Critical Clinical Implications
All children should receive two doses of MMR vaccine regardless of age, as measles vaccination has essentially eliminated SSPE in highly vaccinated populations. 1
The first dose should be given at 12-15 months (or exactly at 12 months in high-risk areas), and the second dose at 4-6 years. 1
Adolescents and adults born after 1957 without documentation of two MMR doses or laboratory evidence of immunity should receive catch-up vaccination to prevent SSPE. 1
The second dose addresses the approximately 5% primary vaccine failure rate from the first dose. 1
Common Pitfall to Avoid
Do not assume that older children or adults who contract measles are protected from SSPE—this is a dangerous misconception. While younger age at infection increases risk, SSPE remains a potential complication of measles infection at any age, and prevention through vaccination is universally critical. 1, 2