Compliance to oseltamivir and subsequent occurrence of self-reported adverse drug reactions among nursery and primary school children following exposure to Influenza A(H1N1)v.

During the containment phase of Influenza A(H1N1)v, a nursery, a primary school and an afterschool club were closed after two pupils were found confirmed cases. Classmates were prescribed postexposure oseltamivir. Compliance was expected to be low. The objective of this study was to assess compliance, the number of children developing adverse drug reactions (ADRs) and the reasons for stopping the course prematurely. We conducted a survey among parents of all classmates of the two cases. Parents were asked about compliance and adverse drug events in a questionnaire or underwent a telephone interview. Response was high, 88%. Seventy-nine percent of the children were compliant to the prescribed dose of oseltamivir. One in four children experienced at least one ADR. Children who took a higher daily dose (treatment dose) developed significantly more often ADRs. No children developed Influenza A(H1N1)v. We found that a high overall compliance to prescribed oseltamivir can be achieved in very young children (1-11 years). The proportion of children developing ADRs was much lower than described in two other recent UK investigations. Possibly, this is related to the socioeconomic status of the population under investigation.