What hasn't been clear in the past is whether RSV and other viruses actually cause asthma, or whether children who are predisposed to asthma are the ones most likely to get such viruses, according to Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital in Detroit.
The current study, which included a group of more than 95,000 infants born between 1995 and 2000, hoped to answer that question.
All of the infants were part of the Tennessee Medicaid program and were followed from birth through early childhood to see if the timing of birth in relation to winter virus season had any effect on the development of asthma.
And, the researchers found that it clearly did. Babies born in the fall, which is generally about four months before the peak of the winter virus season, had a 29 percent higher risk of asthma, according to the study.
For fall-born babies, said Hartert, the winter virus season tends to coincide with a vulnerable period of development, where babies are transitioning from maternal antibodies to their own. But, she said, babies' immune systems aren't really developed until about 6 months of age.
Hartert said she "hopes this study's findings will generate heightened interest in development of an RSV vaccine." She said that RSV is unique among viruses because the human body doesn't ever develop antibodies against it. She said there are vaccines in development currently, but that they're "probably a ways off."
Appleyard said that parents shouldn't worry if they've had, or are going to have a fall baby, "because no one specific trigger is going to be the cause of all asthma."
Likewise, she said, don't feel like you're to blame if your child has ever had RSV, because most children have had this ubiquitous virus.
However, Hartert, Appleyard and Stein all suggested that parents might want to take steps
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