Dubé et al. BMC Public Health 2011, 11:128 http://www.biomedcentral.com/1471-2458/11/128 exclusively, an A(H1N1) pandemic influenza vaccine (Arepanrix™) containing a novel adjuvant (AS03 adju- vant, as an oil-in-water emulsion) was used [8]. Physicians are known to play a key role in public acceptance of new vaccines and their recommendations are an important determinant of vaccine uptake [9-13]. Prior to the A(H1N1) vaccine approval for clinical use and the release of professional association and experts committee recommendations, we documented Canadian family physicians’ and paediatricians’ knowledge, atti- tudes and practice (KAP) regarding A(H1N1) pandemic influenza and its prevention by vaccination [14]. In this study, 59% of paediatricians had had some experience with severe cases of A(H1N1) pandemic influenza and the majority (75%) of them were willing to recommend the A(H1N1) pandemic vaccine to their patients. More than 75% of the respondents also indicated the willing- ness to get the vaccine themselves [14]. The aim of this study was to document paediatricians’ KAP regarding A(H1N1) pandemic influenza and its prevention by vaccination just after the beginning of the A(H1N1) vaccination campaign and to compare these results with those obtained before vaccination campaign initiation. Methods A self-administered, anonymous, mail-based question- naire was sent to all Canadian paediatricians, except subspecialist. The Canadian Medical Directory [15] was used to identify paediatricians. This database con- tains more than 58,000 listings of Canadian physicians medical contact information and is updated each year. A multidisciplinary team developed the questionnaire using the Analytical framework for immunization programs in Canada as a theoretical base [16]. This framework was developed to guide and standardize pub- lic health decision-making process regarding new immu- nization programs in Canada. It includes 58 criteria classified into 13 categories. Three categories of this framework were used to guide the construction of the questionnaire: (1) Burden of disease, (2) Vaccine charac- teristics, and (3) Acceptability of the vaccine program. The final questionnaire included 12 questions on A (H1N1) pandemic influenza and its prevention by vacci- nation as well as 10 questions on KAP about vaccination in general and 10 questions on demographic and profes- sional characteristics of respondents. Respondents were asked to base their answers on their own knowledge and opinions. For most questions, a 6-point Likert answer scale ranging from “strongly disagree” to “strongly agree” was used. No information on A(H1N1) pandemic influenza or the vaccines was provided. The questionnaire was mailed to 1,852 pediatricians. The first two mailings were done in August-September 2009 Page 2 of 9 and the third in November 2009. The last mailing was sent to 1,118 pediatricians who had not responded to the first two mailings. The study protocol was approved by the Ethics Board of the Laval University Hospital Center (reference number 126.05.02). All vaccines authorized for sale in Canada, including the A(H1N1) influenza vaccines, are reviewed and approved by the federal government (Health Canada). However, each province and territory is responsible for the development of publicly funded immunization pro- grams, including the schedules and the logistics of administering vaccines as well as education of the popu- lation and health professionals. The A(H1N1) pandemic vaccine was approved for use in Canada on 21st October 2009 and vaccination campaign started shortly after- wards in all Canadian provinces and territories (within days before or after 29th October 2009). To vaccinate as many persons as possible in the shortest period of time, most Canadian jurisdictions used mass vaccination cen- tres administered by the public system. All provincial and territorial authorities, conjointly with federal autho- rities, have determined a sequence of vaccination by tar- get groups. Throughout Canada, priority to receive the A(H1N1) vaccine was given to healthcare workers. Mass vaccination campaign ended in most Canadian provinces and territories in mid-December 2009. Due to the intense media coverage and the important educational efforts undertaken around the vaccination campaign and their potential impact on physicians’ KAP [17,18], we decided to perform a “before-after” analysis. Questionnaires were analyzed in two subsets: those received before (first subset) and after (second subset) the start of the vaccination campaign (October 29). Descriptive statistics were generated for all variables. Missing responses were excluded from the analyses. Univariate analyses were computed separately for the two data subsets. Comparisons of categorical responses were performed using chi-square or Fisher’s exact tests. A multivariate logistic regression model was used to determine variables independently associated with the paediatrician’s intention to recommend the A(H1N1) pandemic vaccine. Dependent and explanatory variables were dichotomized: the responses “strongly agree” and “agree” versus all others ("strongly disagree”, “disagree”, “somewhat disagree” and “somewhat agree”). Variables associated in the univariate analysis with the intention to recommend the vaccine at p ≤ 0.20 were entered into the multivariate regression models using the stepwise selection technique. The model was adjusted to take into consideration the two subsets of data. A new binary explanatory variable was created (subsequently referred to as “subset variable”) and forced into the model: ques- tionnaires mailed before the beginning of the vaccina- tion campaign and questionnaires mailed after. Variables