Relationship between all fevers or fever after vaccination, and atopy and atopic disorders at 18 and 36 months.

Background: Studies have reported that early febrile episodes and febrile episodes with infections are associated with a decreased risk of developing atopy.

Objective: To examine further the association between presence of and number of febrile episodes are with atopy and atopic diseases and if there was a difference between all fevers and fever after vaccination.

Methods: We studied 448 infants in a Singapore mother-offspring cohort study (Growing Up in Singapore Towards Healthy Outcomes) which had complete data for the exposures and outcomes of interest. Fever was defined as more than 38.0℃ and was self-reported. The presence of and number of febrile episodes were examined for association with outcome measures, namely parental reports of doctor-diagnosed asthma and eczema, and rhinitis, which was evaluated by doctors involved in the study at 18 and 36 months. These outcomes were considered atopic if there were 1 or more positive skin prick tests.

Results: The presence of all fevers from 0-6 months of age was associated with reduced odds of having atopy at 36 months of age (unadjusted odds ratio [OR], 0.628; 95% confidence interval [CI], 0.396-0.995). The presence of fever after vaccination from 0-24 months of age was associated with reduced odds of having atopy at 36 months of age (OR, 0.566; 95% CI, 0.350-0.915). The presence of all fevers from 0-6 months of age was associated with reduced odds of having atopic eczema at 36 months (OR, 0.430; 95% CI, 0.191-0.970). Fever was associated with increased odds of having doctor-diagnosed asthma and rhinitis.

Conclusion: There was an inverse relationship between the presence of all fevers from 0-6 months of age and the development of atopy and eczema at 36 months of age. Fever after vaccination might be considered a subclinical infection that did not show the same effect in early life.