Outcomes
SECONDARY, INFLUENZA
The pre-registered primary outcome for this study was the proportion of eligible children in the school years for each of years 1–3 (i.e. those aged 5 to 7 years on 31st August 2016) who received influenza immunisation as part of the national childhood immunisation programme. We focused only on children in years 1–3 during the 2016/17 winter season as they were the target age group for the national childhood influenza immunization campaign. The secondary outcomes also pre-registered were the proportion for whom the consent form was returned, the proportion of consent forms returned with consent granted, and the proportion of consent forms returned with consent denied.