Influenza surveillance during the 2009-2010, 2010-2011, 2011-2012, and 2012-2013 seasons in Algeria.

We report the activity and circulation of influenza viruses in Algeria during four influenza seasons, from a national surveillance study carried out from 2009-2010 to 2012-2013. A total of 2766 samples from in- and outpatients, with no age restriction, were collected. The overall proportion of specimens that tested influenza positive was 46.0%. Overall, 96.6% of influenza A viruses were subtyped, and A/H1 subtypes accounted for 57.3% of influenza A viruses. Influenza A/H1 and A/H3 virus subtypes cocirculated in 2009-2010. In 2010-2011, a high proportion of type B viruses (66.2%) was observed. The subtype H3N2 was identified in 99% of cases typed in 2011-2012. Influenza A/H3N2 and B virus cocirculated in 2012-2013. A remarkably low influenza vaccination rate of 2.4% was observed among all age groups. Antibiotics were prescribed for 926 (41.3%) patients, and no difference was observed between patients with confirmed influenza and patients with influenza-like illness not related to influenza. The burden of influenza is largely undocumented in Algeria and strategies to expand this surveillance across the country are needed. Strategies to increase vaccination coverage are warranted to control and prevent influenza in individuals at risk of complications as well as in the general population.