[Daily Surveillance of Pandemic Influenza (H1N1) 2009 by primary care electronic clinical records in the Madrid region].

Background: Pandemic influenza (H1N1) 2009 led to implementation in the Madrid Region of new strategies of epidemiology surveillance in order to give response to the need of immediacy and exhaustiveness.
Methods: Descriptive cross-sectional study between May 1th 2009 and May 22th 2010. All disease episodes registered and reported as influenza disease were collected every day from electronic clinical records in primary care of Madrid Regional Public Health System. Data were analyzed by date, age, sex and health zoning, disaggregating into health professionals.
Results: 165.492 influenza episodes were registered (53,8% in women). The main number of cases was in the 25-49 years group (70.691), and the 5-14 years group reached the maximum weekly incidence rate (1.618,65/100.000 in the week 43). The highest weekly total incidence rate was 458,47/100.000 (week 44). Pediatricians reached the maximum of cases visited and of cumulated rates (12 pediatricians visited more than 20% of their total assigned population).
Conclusions: Surveillance of pandemic influenza (H1N1) 2009 by automatic daily data collection from electronic clinical records in primary care has meant a specially useful information source for monitoring the development of pandemic influenza and for the strategic decision making.