Ebola Disruptions: Can Measles Catch-Up Protect

Why can Ebola-related care disruptions increase measles risk?

The consequences of an Ebola outbreak can extend beyond people infected with the virus. When routine vaccination is interrupted, children may miss protection against unrelated diseases. In guidance updated in September, WHO emphasizes that routine immunization should continue during Ebola outbreaks wherever it can be provided safely. Even brief interruptions can increase vulnerability to measles, polio and diphtheria. This makes childhood vaccination an essential part of maintaining health services during an outbreak. [WHO: Ebola vaccines](https://www.who.int/news-room/questions-and-answers/item/ebola-vaccines).

Measles is particularly concerning because it spreads readily through the air and can cause pneumonia, severe diarrhea and encephalitis, an inflammation of the brain. Young children are especially vulnerable to complications. Missing a vaccine does not itself cause an infection, but it can leave a child susceptible when exposure occurs. The possibility of a secondary outbreak is therefore a public health risk to address, not proof that a new measles outbreak has already begun. [WHO: Measles](https://www.who.int/news-room/fact-sheets/detail/measles).

Does a child need to restart measles vaccination after a delay?

Catch-up vaccination starts with reviewing which doses a child has already received and which remain due. CDC guidance states that delayed childhood vaccine series do not need to be restarted simply because time has passed. However, clinicians must check the child's age when previous doses were given, the intervals between doses and any medical precautions. Families should bring available vaccination records so the next appointment can address the actual gap. National schedules differ, so an individual plan should follow local recommendations. [CDC: Catch-up Immunization Schedule](https://www.cdc.gov/vaccines/hcp/imz-schedules/child-adolescent-catch-up.html).

Completing the recommended course matters. CDC estimates that one dose of measles vaccine is approximately 93% effective at preventing measles, compared with approximately 97% after two doses. These are estimates of protection, not guarantees for every recipient. WHO explains that the second dose provides another opportunity for children who did not develop immunity after their first vaccination. A missed second appointment therefore deserves follow-up even when the first dose is documented. [CDC: Measles Vaccine Recommendations](https://www.cdc.gov/measles/hcp/vaccine-considerations/index.html), [WHO: Measles](https://www.who.int/news-room/fact-sheets/detail/measles).

How can health services help children catch up during an outbreak?

WHO recommends making catch-up vaccination a continuing part of routine care. Its guidance calls for identifying eligible people who missed doses and vaccinating them at the earliest opportunity. Following substantial service disruption, additional efforts may be needed to reach children who have fallen behind. The practical implication is that reopening appointment slots alone may be insufficient: services also need a way to find missed children and help them return. [WHO: Leave no one behind](https://www.who.int/publications-detail-redirect/9789240016514).

During an active Ebola outbreak, vaccination arrangements must also follow local infection prevention measures. WHO's advice to continue routine immunization is conditional on safe delivery; families should confirm where services are operating and follow instructions from their local health team. Catch-up planning and infection prevention need to work together so children can regain protection without assuming that every clinic is operating normally. [WHO: Ebola vaccines](https://www.who.int/news-room/questions-and-answers/item/ebola-vaccines).