Dr. Monica Gandhi, a professor of medicine at the University of California San Francisco, who was not involved in the new research, said it is important to reassure parents about the safety of vaccines.
Asthma is a condition in which your airways narrow and swell and may produce extra mucus. This can make breathing difficult and trigger coughing, a whistling sound (wheezing) when you breathe out and shortness of breath.
A new study found a possible link between aluminum used in early childhood vaccines and the risk of children developing asthma before age 5. However, the authors of the study caution that the results are not strong enough to suggest “questioning the safety of aluminum in vaccines.” Instead, they call for additional research to better understand this risk. This might include studies using other large vaccine safety databases, and laboratory studies looking at children’s immune responses after vaccination.
Aluminum is used in many vaccines as an adjuvant which helps create a stronger immune response in people who receive a vaccine. Childhood vaccines that contain an aluminum adjuvant include Diptheria, tetanus, and acellular pertussis (DTaP); hepatitis B; Haemophilus influenzae type b (HiB) vaccine; and pneumococcal conjugate vaccine. The COVID-19 vaccines and seasonal flu vaccines do not use an aluminum adjuvant.
The authors of the new study noted that there has been conflicting prior research on the relationship between childhood vaccinations and asthma. While other studies indicated no greater risk or a much lower risk of asthma, one research found a little elevated risk of asthma in kids who received specific vaccinations. But unlike the present investigation, none of these studies specifically examined the exposure to aluminium in vaccinations. Additionally, according to CDC data, asthma rates among American kids rose in the 1980s and 1990s but mostly stayed the same between 2001 and 2016. Thus, a number of causes are probably causing these developments.
The new study is based on electronic health records of nearly 327,000 children born between 2008 and 2014 who received care at seven sites that participate in the Vaccine Safety Datalink, a collaboration with the CDC to study vaccine safety. The researchers divided the children into two groups those with a diagnosis of eczema by 12 months of age and those without.
Like asthma, an eczema is a form of allergic disease. Children with eczema also have a higher risk of developing persistent asthma. So if there is a link between aluminum in vaccines and the risk of developing asthma, it might show up differently in the two groups.
Researchers estimated each child’s exposure to aluminum by looking at how many vaccines they received before the age of 2. They then looked to see which children developed persistent asthma between the ages of 2 and 5. Researchers defined persistent asthma as children having at least one inpatient healthcare visit or two outpatient or emergency department visits for asthma, and receiving at least two prescriptions for long-term asthma medication.
In both children with and without eczema, researchers found a positive association between exposure to aluminum in vaccines and the risk of developing asthma. The risk was higher for children with eczema. This association remained when researchers accounted for other factors such as sex, race, ethnicity, food allergies, and the number of healthcare visits. However, in some of the other analyses that the researchers did, the association was no longer present.
The study was published in the journal Academic Pediatrics.
Dr. James Gern, a professor of pediatrics and vice chair of research in the School of Medicine and Public Health at the University of Wisconsin-Madison, said that one of the strengths of the study is that it included a large number of children. Gern was not involved in the new study. However, he said because this was a retrospective study looking back at medical visits that have already happened it can raise questions, but can’t provide definitive answers.
One reason for this is that in this kind of observational study, it is impossible to rule out all “confounders,” said Gandhi. For example, “aluminum is also found in dietary and other sources,” said Gandhi, such as breast milk, formula, and solid foods.
The authors of the new study did not have data on children’s dietary aluminum exposures. But some research suggests that “little to none of the ingested aluminum appears to be absorbed,” so the absence of this data may not have impacted the results of the new study. Other environmental factors and genetics can also increase a child’s risk of developing asthma.