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

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

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.

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.

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.

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.