To decrease data entry for the clinic staff date of birth and gender were entered on-line by survey respondents. The survey provided simple check-boxes and free text boxes as required. The 2013 Vaxtracker online survey was simplified by adding a screening question so that the 11 symptom questions

only appeared if the parent or carer clicked “yes” to the question: “Did (child’s Inhibitor Library order first name) experience and kind of reaction, illness or discomfort after the vaccination?” An answer of “yes” to any of the symptom questions in the first online survey activated a drop down box with additional questions regarding severity, whether medical advice was sought and duration of the event. The 11 symptoms explored in the 2012 and

2013 pilot studies were: reaction at injection site, fatigue, influenza-like illness, muscle aches, headaches, joint pain, fever, LY2109761 lymph node swelling, weakness, seizures and “other” symptoms. Recruitment and adverse events were reviewed by surveillance staff to detect any signal of adverse events. Data on recruitment and adverse events were available through the dedicated secure website and was downloaded twice weekly to monitor adverse events, recruitment by each clinic and prepare weekly reports. An automated email alert to the Vaxtracker team was generated when a seizure or hospitalisation was reported so that review could occur rapidly. Survey completion rates were calculated as the number of participants who completed the survey divided by the total participants due to have completed the survey. Weekly reports were shared with health departments at State and National level and a final report with the Therapeutic Goods Administration (TGA). All serious adverse events including high fever, seizures, unresolved systemic symptoms or hospitalisation were Digestive enzyme followed up by telephone by a registered nurse and reviewed with a public health physician and if required notified to NSW Health through usual AEFI notification channels. Adverse events were described according to demographic characteristics of the participants, previous vaccine history and the brand of IIV administered.

Factors associated with adverse events were investigated by comparing participants who experienced an adverse event with those who did not experience an adverse event by the following factors; age (t test of mean age), gender and first year of IIV administration (comparison of proportions using Pearsons Chi-squared test). The analysis controlled for gender, age by year and whether first time influenza vaccine was received in the current season. There is a Vaxtracker Standing Operating Procedure for validating reports that are questionable with attending clinicians. Surveillance of AEFIs is conducted in NSW under the NSW Public Health Act, therefore ethical review was not required for this enhancement to existing surveillance.