Asthma and respiratory viruses don't go well together. Weakened by the common cold or the flu, a person suffering an asthma attack often responds poorly to emergency treatment; some must be hospitalized. This is especially true for preschoolers. But what if there were a simple solution to help ward off the double whammy of an asthma attack and a respiratory virus? Well, there is one: to prevent getting sick, asthmatics can get an annual flu shot. Unfortunately, however, only about 60% do, but that might change.
In a new study in the journal Pediatrics, researchers at the Université de Montréal-affiliated CHU Sainte-Justine children's hospital and a master's student in epidemiology at McGill University make a strong case for vaccinating asthmatic kids against flu. Just over 1 in 10 Canadian children have asthma, about 600,000 under the age of 12. The chronic disease often starts in early childhood—before age six years, in the preschool years. "These kids should get their flu shot and they should get it systematically—it's worth it," said study coauthor Francine Ducharme, a pediatrician and clinical epidemiologist at CHU Sainte-Justine who's a professor of pediatrics at UdeM.
"We now know that if these kids get the flu the risks are very high that emergency treatment for an asthma attack will fail," said Ducharme. "Instead of having an overall 17% risk of treatment failure, with flu their risk rises to almost 40%." The study is based on the national DOORWAY (Determinants Of Oral Corticosteroid Responsiveness in Wheezing Asthmatic Youth) study that Ducharme and colleagues conducted between 2011 and 2013, with funding from the Canadian Institutes of Health Research. That study looked at close to 1,000 children treated for moderate or severe asthma attacks in emergency rooms at Sainte-Justine, the Montreal Children's Hospital, and three other Canadian hospitals. Nose swabs were taken and analyzed to see if the children also had the flu or other respiratory viruses when they came to the ER.
It turned out almost two-thirds did. Yet when the kids with respiratory viruses were given the standard treatments for their asthma attack—oral corticosteroids and inhaled bronchodilators—20% didn't respond and in most cases needed to be hospitalized. Those with influenza or parainfluenza turned out to have a 37% or more chance of not responding to treatment, compared to 13% for children without a virus. Failure was also high in kids with respiratory syncytial virus (RSV).
By contrast, kids with strains of human rhinoviruses (HRVs)—the usual cause of the common cold—did respond well to treatment for their asthma. To the researchers, this was very reassuring, as HRVs are the most frequent trigger of asthma attacks necessitating a visit to the ER.
"This is the first time we've been able to disentangle the risk of non-response to asthma treatment with the presence of specific viruses—specifically, influenza and rhinovirus," said coauthor Caroline Quach, an associate professor of microbiology and infectious diseases at UdeM, chair of the Quebec Immunization Committee, and chair of the National Advisory Committee on Immunization of the Public Health Agency of Canada. "The more than 20% higher absolute risk of treatment failure in flu cases is very significant."
There's also a simple solution, but with hurdles, she added. "Influenza is the only respiratory virus that is vaccine-preventable. Granted, it's at best only 50% efficacious, but that's no reason for kids with asthma not to get vaccinated yearly, in the fall, before flu season starts. We can start as young as age 6 months. Asthma is not usually diagnosed that early, but in Quebec every child who is diagnosed with asthma is eligible for influenza vaccination. The problem is that not many parents are prevailing themselves of the opportunity."
A major reason is access. Getting a flu shot often means an extra trip to a physician's office clinic, and not all parents can or want to take the time to get it done. "It's an additional step, so what we're trying to promote is that kids get vaccinated where they get care—at Sainte-Justine, for example, where children can be vaccinated onsite at our asthma, respiratory, or general pediatric clinics."
Dr. Kenneth Backman of Allergy & Asthma Care of Fairfield County comments: "We have long known of the link between viral infections and asthma exacerbations. This study is unique in that it quantifies the relation between treatment response and specific infections. This study once again emphasizes the importance of influenza vaccination in all asthma patients. Our office offers influenza vaccination to all of our patients."