Over the past week in the region:

• Very high flu activity last week, during the fifth week of the epidemic. All indicators reached levels far higher than in previous years (SOS doctors, emergency room visits, and virus isolations by virology laboratories). Analysis of daily data from last week shows that a plateau has been reached, indicating a slowdown in virus transmission. A decline can reasonably be expected in the coming weeks.

• Nationally, the predominance of a variant of the A(H3N2) virus, which differs from the vaccine strain, has been confirmed. The vaccine’s efficacy against this virus, as assessed in North America, is very low to nonexistent.

• This epidemic has a particular impact on the elderly, with emergency room visits and mortality rates exceeding expected thresholds. A total of 26 cases of severe influenza have been hospitalized in intensive care since the start of the season; nearly half of them are over 65 years of age.

• Outbreaks of acute respiratory infections (ARI) in nursing homes are rising sharply, with 22 new outbreaks in the past week out of the 84 reported since September 2014. The hospitalization rate is higher than that observed in previous years (9.7% vs. 7%). Recommendations for the use of antivirals for both treatment and prevention have been distributed to nursing homes (HCSP advisory of November 9, 2012).