Highlight: Start of winter surveillance for the 2013–2014 season

As is customary in week 40 each year, surveillance for winter illnesses begins. Indicators for gastroenteritis, influenza-like illness, and bronchiolitis will be presented in the Epidemo Reports through week 15 of 2014. During the previous season (2012–13), mainland France experienced a more intense community-based influenza epidemic than in the three preceding seasons, lasting 13 weeks—the longest among the 29 seasonal epidemics monitored since 1984. The epidemic began in late December and peaked two months later, exceeding the peak of the 2009 pandemic and subsequent seasons. Influenza viruses A(H1N1)pdm09, A(H3N2), and type B circulated, with type A viruses initially dominant; this trend reversed in favor of type B viruses by late January. The number of outbreaks of acute respiratory infections in long-term care facilities remained lower than in 2011–12. The number of flu-related visits to emergency departments increased compared with the two previous flu seasons. Among these patients, 6.8% were hospitalized, a proportion significantly lower than that of the previous season (8.2%). In total, 818 severe cases were admitted to intensive care, a number higher than in the previous season but lower than the 1,305 severe cases during the pandemic. These severe cases, younger than in 2011–2012, were primarily infected with the A(H1N1)pdm09 virus. The case fatality rate for severe cases remained comparable to that observed in 2011–12, 2010–11, and 2009–10. In conclusion, the 2012–13 influenza epidemic was particularly long, marked by the co-circulation of three influenza viruses. Consequently, even though the severity of the flu during this season was comparable to that of previous seasons, the impact of the epidemic in terms of visits for flu-like symptoms and hospitalizations was greater. An article in the BEH is dedicated to the summary of flu surveillance for the 2012-2013 season.