Undernutrition may be key driver of measles outbreaks in low- and middle-income countries

There were an estimated 136,200 deaths caused by measles across the globe in 2022, primarily affecting children under the age of five. The global number of cases of measles had declined from 2000–2016, then reversed in 2018, in part due to the pandemic and undervaccination.

But a new study from a collaboration between researchers at the UC Berkeley School of Public Health, McGill University, and the University of Pretoria shows that undernutrition may also play an important role in measles outbreaks in low- and middle-income countries, even in children who have been vaccinated.

“Our results show that child undernutrition could have a negative impact on the efficacy of vaccines by compromising the immune system’s ability to mount an effective response to certain types of vaccines,” said Professor Brenda Eskenazi, lead author of the paper, which was published in Vaccine, and director of the Center for Environmental Research and Community Health at UC Berkeley School of Public Health.

The research also indicates that undernutrition can affect the longevity of vaccine protection.

The study followed 621 fully-vaccinated children up to age five in South Africa, all part of the Venda Health Examination of Mothers, Babies and the Environment (VHEMBE) birth cohort. Children who were stunted or had any indicator of diminished growth at three and a half years old showed a 24.1% or 27.2% lower level of antibodies for measles, respectively, compared to the children with normal growth.

“For certain vaccines, such as the tetanus vaccine, our data suggest that some of the negative impacts of undernutrition may be sex specific with girls being less likely to be protected than boys,” said Eskenazi.

“Approximately 22.3% or 148 million children under five years worldwide in 2022 are stunted, with the highest burden in Asia and sub-Saharan Africa,” said Jonathan Chevrier, Associate Professor of Epidemiology at McGill University and principal investigator of the study. Undernutrition is associated with deficiencies in energy and essential nutrients that may impair the development of an adequate immune response to vaccines.”

Furthermore, even if a sufficient response had initially developed, an undernourished child may not maintain long-term protection.

“It is imperative that we vaccinate children against infectious diseases to prevent unnecessary disease and deaths,” said Eskenazi. “Given our data suggesting that children who are undernourished may not be protected adequately even when fully vaccinated, we must also address worldwide undernutrition in children. This is especially important with climate change and the future possibility of new infectious diseases.”