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A recent study has revealed that undernutrition may significantly contribute to the persistence of measles outbreaks in low- and middle-income countries, even among children who have received vaccinations. The study, published in the Vaccine journal, was conducted by researchers from UC Berkeley School of Public Health, McGill University, and the University of Pretoria. It highlights the critical role undernutrition plays in weakening the immune response to vaccines, making children more vulnerable to infectious diseases.
The global impact of measles is concerning, with an estimated 136,200 deaths recorded in 2022, most of which occurred in children under five. While the number of measles cases had been steadily declining from 2000 to 2016, the trend reversed starting in 2018, a change exacerbated by the COVID-19 pandemic and insufficient vaccination efforts.
Professor Brenda Eskenazi, lead author of the paper and Director of the Center for Environmental Research and Community Health at UC Berkeley, emphasized the link between undernutrition and vaccine efficacy. “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,” she said. The study also suggests that undernutrition may impact the longevity of vaccine protection, potentially leaving children vulnerable long after receiving their vaccinations.
The research tracked 621 fully vaccinated children up to the age of five in South Africa, as part of the Venda Health Examination of Mothers, Babies and the Environment (VHEMBE) birth cohort. Findings showed that children who were stunted or exhibited signs of diminished growth at three and a half years old had antibody levels 24.1% to 27.2% lower than those with normal growth. This discrepancy points to a weakened immune response, particularly in relation to measles, despite vaccination.
Moreover, the study revealed that the impact of undernutrition on vaccine response might differ by sex, with girls less likely to maintain adequate protection, especially from vaccines like the tetanus shot.
Undernutrition remains a significant global health challenge, with nearly 148 million children under five years old affected by stunting in 2022, the majority of whom live in Asia and sub-Saharan Africa. Jonathan Chevrier, Associate Professor of Epidemiology at McGill University, explained, “Undernutrition is associated with deficiencies in energy and essential nutrients that may impair the development of an adequate immune response to vaccines.”
The study’s findings underline the importance of addressing undernutrition in parallel with vaccination efforts. “It is imperative that we vaccinate children against infectious diseases to prevent unnecessary disease and deaths,” Eskenazi urged. “However, given our data suggesting that undernourished children may not be adequately protected even when fully vaccinated, we must also prioritize the global fight against childhood undernutrition.”
As climate change and potential new infectious diseases pose increasing challenges, the study underscores the need for comprehensive strategies that tackle both malnutrition and vaccine accessibility to protect the health of the world’s most vulnerable children.
For further information, see the study: Brenda Eskenazi et al, Undernutrition and antibody response to measles, tetanus, and Haemophilus influenzae type b (Hib) vaccination in pre-school South African children: The VHEMBE birth cohort study, Vaccine (2024). DOI: 10.1016/j.vaccine.2024.126564.
