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Allergic sensitization and viral respiratory illness may increase asthma risk

Published online: April 13, 2020

Asthma is the most common chronic childhood disease. Many factors, including genetics and the environment, have been considered important in the development of asthma. There has been interest in whether early childhood viral respiratory illness has greater effects in allergic sensitized children and thereby increases their risk for later asthma. While viral illnesses in childhood are common, there remains uncertainty whether and how these may affect allergic sensitized children differently to children who are not sensitized. It has been considered that allergic children may have immune system defects that could put them at a higher risk of developing asthma if exposed to early life viral respiratory illness.

Wadhwa et al report in The Journal of Allergy and Clinical Immunology: In Practice the results of their systematic review that considers whether there is evidence for an association between viral respiratory illness and allergic sensitization in children who develop persistent wheezing and asthma. Their review included all human studies that have investigated this association. They have undertaken a meta-analysis to investigate the magnitude of the effect in wheeze and asthma outcomes that relates to the association of viral illness in children according to their allergic sensitization status.

There were a total of 9 studies that were considered for the systematic review and, of these, 4 followed children from birth and were included in the meta-analysis. They found that there appeared to be greater association between early life viral respiratory illness and asthma in children who had allergic sensitization compared to those who did not. They also observed that the difference between the two groups was greatest up to the age of 7 years. However, they acknowledge that the conclusions were limited by the few available studies of small sample sizes that investigated this association.

The findings suggest that there may be a greater effect of viral respiratory illness on subsequent wheezing and asthma outcome in children who have allergic sensitization. This difference was most strongly observed in children aged up to the age of 7 years. The clinical implications of this study are that protection of the developing respiratory system in at risk groups through prevention of infection may be crucial.  In these groups, approaches to optimise immunity and minimise exposure to other noxious agents should also be considered.  

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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