No Link Between Childhood Vaccinations and Allergies or Asthma

Joel N. Shurkin

July 23, 2021

A meta-analysis by Australian researchers found no link between childhood vaccinations and an increase in allergies and asthma. In fact, children who received the BCG vaccine actually had a lesser incidence of eczema than other children, but there was no difference shown in any of the allergies or asthma.

The researchers, in a report published in the journal Allergy, said, "we have found no evidence that childhood vaccination with commonly administered vaccines was associated with increased risk of later allergic diseases."

"The epidemic was first noted in developed countries, but developing countries are catching up," said Caroline J. Lodge, PhD, principal research fellow at the University of Melbourne in Australia, and one of the authors, in an interview with Medscape Medical News. "In developing countries, it is still a crisis." No one knows why, and that was the reason for the recent study, she said.

Allergic diseases such as allergic rhinitis and food allergies have a serious influence on quality of life, and the incidence is growing. According to the Global Asthma Network, there are 334 million people living with asthma. Between 2% and 10% of adults have atopic eczema, and more than a quarter of a million people have food allergies. This coincides temporally with an increase in mass vaccination of children. "This is especially true of asthma and to a lesser extent, food allergies," Lodge said.

Unlike the controversy surrounding vaccinations and autism, which has long been debunked as baseless, a hygiene hypothesis postulates that vaccination may influence children's immune responses to become more allergic.

That immunity leads to suppression of a major antibody response, increasing sensitivity to allergens and allergic disease. Suspicions of a link with childhood vaccinations has been used by opponents of vaccines in lobbying campaigns jeopardizing the sustainability of vaccine programs. In recent days, for example, Tennessee has halted a program to encourage vaccination for COVID-19 as well as all other vaccinations, the result of pressure on the state by antivaccination lobbying.

But the Melbourne researchers reported that the systematic review of 42 published research studies doesn't support the vaccine-allergy hypothesis. Using PubMed and EMBASE records between January 1946 and January 2018, researchers selected studies to be included in the analysis, looking for allergic outcomes in children given BCG, or vaccines for measles or pertussis. Thirty-five publications reported cohort studies, and seven were based on randomized, controlled trials.

Vaccination was compared with placebo or with no vaccination. "These represent the best objective evidence," Lodge said. "They showed no increase in allergic disease and suggested protection from eczema."

The Australian study is not the only one showing the same lack of linkage between vaccination and allergy. The International Study of Asthma and Allergies in Childhood found no association between mass vaccination and atopic disease. A Swedish study of 669 children found no differences in the incidence of allergic diseases between those who received pertussis vaccine and those who did not.

"The bottom line is that vaccines prevent infectious diseases," said Matthew B. Laurens, MD, associate professor of pediatric infectious diseases at the University of Maryland School of Medicine in Baltimore, in an interview with Medscape Medical News. Laurens was not part of the Australian study. "Large-scale epidemiological studies do not support the theory that vaccines are associated with an increased risk of allergy or asthma. Parents should not be deterred from vaccinating their children because of fears that this would increase risks of allergy and/or asthma."

Allergy. Published online March 20, 2021. Abstract

Lodge and Laurens report no relevant financial relationships.

Joel Shurkin was a national reporter for Reuters in New York and covered the space program. He was science editor at the Philadelphia Inquirer and science writer and instructor in science journalism at Stanford University, the University of California Santa Cruz, and the University of Alaska Fairbanks. He was part of the team that won a Pulitzer Prize at the Inquirer. He is the author of 10 books on science and the history of science.

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