Declining number of children being vaccinated against measles in Aotearoa

There are not enough children under the age of 5 in Aotearoa protected against measles to stop a potential national outbreak, a new University of Otago, Christchurch study shows.

This is because the number of children receiving the first measles, mumps and rubella (MMR) vaccine is declining.

Reported in the New Zealand Medical Journal today, coverage for the first MMR vaccine has decreased from 95.1% for children born in 2017 to 88.9% for those born in 2020.

Lead author Dr. Nienke Hagedoorn, of the Department of Pediatrics, says immunization coverage for measles is insufficient to prevent community transmission in children under 5. More than 95% coverage for the first vaccine is required.

"This is important because young people who are unvaccinated are at high-risk for measles-related complications, such as hospital admissions or even death," Dr. Hagedoorn says.

Researchers used data from the National Immunization Register to investigate how many children born between 2017 and 2020 in Aotearoa received the first and second MMR vaccine.

Results show children of Māori ethnicity had the lowest coverage for the first vaccine and this declined over time, from 92.8% for the 2017 birth cohort to 78.4% for 2020.

The number of children who received the first vaccine is declining in all Te Whatu Ora locations. Six locations—Bay of Plenty, Lakes, Northland, Tairawhiti, West Coast and Whanganui—had, on average, less than 90% coverage for the first vaccine during the study period.

Overall, the coverage for the first vaccine was 92.5% for children born between 2017 and 2020.

Dr. Hagedoorn says nationwide catch-up immunization programs are urgently needed to improve immunization coverage and prevent an outbreak.

"Since the borders in New Zealand have fully opened and the number of measles cases around the world has increased, the chances of measles being imported into New Zealand have also gone up."