Iron deficiency cuts vaccine protection, according to new research.
About 40% of children around the globe suffer from anemia because they don’t consume enough iron.
Despite the fact that global immunization programs now reach more people than ever, about 1.5 million children still die every year from diseases that vaccination could have prevented. Vaccination is also less effective in low-income countries than in high-income countries, although it is not yet clear why.
Findings in Frontiers in Immunology from two clinical studies with children in Kenya now suggest that iron deficiency during infancy may reduce the protection that vaccinations provide.
Babies with anemia
In the first study, researchers wanted to determine the levels of body iron and antibodies against antigens from the administered vaccines in blood samples of 303 Kenyan children followed from birth to age 18 months.
“In Switzerland, babies are born with iron stores that are normally sufficient for their first six months of life,” says Michael Zimmermann, professor of human nutrition at ETH Zurich. “But in Kenya and other sub-Saharan countries, iron reserves in babies are much lower, especially in those born to anemic mothers or with a low birth weight.”
Infections and bloody diarrhea aggravate the problem, and babies’ iron reserves are often exhausted after two to three months, he says.
The study shows that more than half the children already had anemia at the age of 10 weeks, and by 24 weeks, more than 90% had low hemoglobin and red blood cell counts.
Using statistical analyses, the researchers found that, despite several vaccinations, the risk of finding a lack of protective antibodies against diphtheria, pneumococci, and other pathogens in the blood of 18-month-olds was more than twice as high in anemic infants compared to those who were not anemic.
Iron and vaccinations
In a second study, the researchers administered a powder containing micronutrients to 127 infants slightly over six months old on a daily basis for four months. In 85 of these children, the powder also contained iron; the other 42 children received no iron supplement.
When the children received vaccine against measles at the age of nine months—as the Kenyan vaccination schedule stipulates—those children who also received iron as a dietary supplement developed a stronger immune response in two respects: not only did they have more measles antibodies in their blood at the age of 12 months, but their antibodies did a better job recognizing the pathogens.
The World Health Organization (WHO) recommends feeding infants exclusively with breastmilk for the first six months to avoid infection with diseases transmitted in contaminated water.
For that reason, Zimmermann and his research team did not give the children the dietary supplement powder until they were seven months old, although most of the vaccinations had generally been administered by this point; the measles vaccination was the only exception.
However, Zimmermann says that many places have made great progress with their water supply and health systems in recent years, which is why discussions in professional circles about updating the WHO’s recommendation are becoming ever more important.
He believes that adapting the recommendation would be a good move because preventing anemia in young children by supplementing the iron in their diet would improve the protection provided by other vaccinations. In turn, this may help to prevent many of the 1.5 million annual deaths due to vaccine-preventable diseases.
Source: Ori Schipper for ETH Zurich