H1N1 Novel Influenza A Activity Report
Surveillance for the 2008-09 influenza season started October 1, 2008. Hospitalized cases of influenza are reported to the Minnesota Department of Health. The first laboratory-confirmed, hospitalized influenza case (seasonal influenza A) occurred in early December. The first hospitalized seasonal influenza type B case occurred in early January (Figure 1).
Peak seasonal influenza activity lasted from early February to early March. During this time, seasonal influenza A virus infection accounted for the majority of hospitalizations. Seasonal influenza B virus accounted for the majority of hospitalizations from late March through mid-May.
The first laboratory-confirmed, hospitalized case of Novel H1N1 influenza virus occurred in mid May and has since accounted for the vast majority of influenza hospitalizations. Hospitalizations for novel H1N1 influenza virus peaked during mid to late June and has decreased over the past several weeks. While data over weeks 26 and 27 are preliminarily, activity of Novel H1N1 influenza appears to be waning in Minnesota.