ba Van Buynder 2010.

Methods	Pandemic vaccines; case–control study on vaccine efficacy Carried out on children under 10 years of age with ILI who were tested for H1N1 infection at the central provincial laboratory. Laboratory‐confirmed influenza was the primary outcome and vaccination status the primary exposure to assess VE.
Participants	All children throughout New Brunswick, 6 months to 9 years of age, who were tested for H1N1 were selected for inclusion. Children were classified as cases if the respiratory sample was H1N1 positive. Children were classified as a control if the  test was negative and the child met a clinical case definition of ILI (the presence of fever and at least 1 respiratory symptom or sign). Information on age, sex, hospitalisation, indigenous status, prematurity, immunosuppression, coexisting medical conditions, previous seasonal vaccination, and recent pandemic vaccination was collected by direct telephone interview. The diagnosis of an ILI was confirmed using a simple questionnaire. The interviews were conducted by staff from CDCB.
Interventions	Vaccination status and date of vaccination was determined through access to New Brunswick’s universal pandemic vaccination registration programme. This programme recorded the personal details of every person vaccinated in New Brunswick, including the date of administration. Children were classified as vaccinated if the child had received a dose of the H1N1 vaccine at least 14 days before the onset of symptoms and as "not vaccinated" if the child had received no vaccination or had received the first dose < 14 days before the onset of symptoms. No child in the study was 14 days' postreceipt of a second vaccine dose.
Outcomes
Funding Source	Government
Notes	The authors conclude that “A single 0.25 ml dose of the GSK adjuvanted vaccine (Arepanrix) protects children against laboratory‐confirmed pandemic influenza potentially avoiding any increased reactogenicity associated with second doses. Adjuvanted vaccines offer hope for improved seasonal vaccines in the future”. This is a poorly reported study in which selection criteria for cases are not clearly described.
Risk of bias
Bias	Authors' judgement	Support for judgement
CC‐Case Selection	High risk	Insufficient description
CC‐Control Selection	Unclear risk	Possibly drawn from the same population
CC‐Comparability	Unclear risk	Adjustment by confounding factors
CC‐Exposure	Unclear risk	Structured interview
Summary assessments	High risk	Plausible bias that seriously weakens confidence in the results