From the Guidelines
Unvaccinated infants under 12 months of age are most at risk from measles. These young children are particularly vulnerable because they have lost the protective maternal antibodies they received during pregnancy but are still too young to receive the first dose of the measles vaccine, which is typically administered at 12-15 months of age. This creates a critical immunity gap. Infants who contract measles face higher rates of complications including pneumonia, encephalitis, and death compared to older children. The risk is especially high in settings where there is ongoing measles transmission or outbreaks. According to 1, children aged 6-11 months should receive a dose of monovalent measles vaccine before traveling or living abroad, highlighting the increased risk for this age group. To protect these vulnerable infants, it's essential to ensure high vaccination rates in the surrounding community to provide "herd immunity," and to vaccinate all eligible family members and caregivers. In outbreak situations, infants as young as 6 months may receive an early dose of measles vaccine for temporary protection, though they will still need the regular doses at the recommended ages. Key considerations for protecting unvaccinated infants under 12 months of age include:
- Ensuring high vaccination rates in the surrounding community
- Vaccinating all eligible family members and caregivers
- Administering an early dose of measles vaccine in outbreak situations for infants as young as 6 months
- Providing temporary protection with monovalent measles vaccine for infants aged 6-11 months traveling or living abroad, as recommended by 1.
From the Research
Unvaccinated Children at Risk for Measles
- Unvaccinated children with compromised immune systems are at a higher risk for severe complications from measles, including death 2
- Measles infection can lead to immune suppression for weeks to months, making children more susceptible to secondary bacterial and viral infections 3, 4
- Younger children are at a higher risk for complications from measles, and treatment with vitamin A is recommended to decrease mortality 4, 5
- Children with underlying health conditions, such as those with HIV or cancer, are at a higher risk for severe measles and may experience a higher case fatality rate 2
- The absence of a rash does not rule out measles, and immunocompromised patients may not always exhibit typical symptoms 2