Flu activity in the U.S. rises for fourth week

The United States’ flu activity recently rose for the fourth week in a row, and, for the first time, the number of positive results for the 2009 H1N1 virus topped that of the H3N2, which had previously dominated.

According to a report published by the Centers for Disease Control and Prevention, most indicators have increased, including visits to the doctor for flu-like symptoms, CIDRAP News reports. That particular marker rose by .6 percent, up from four percent of all recorded visits. The baseline in the United States is 2.5 percent.

The flu expanded both its reach and intensity in recent weeks. Only 13 states have not reported widespread flu activity. Nine states reported that they had regional activity. The District of Columbia was the only location that reported local activity.

The CDC tracks lab-confirmed flu cases through its FluSurv-NET system. The system recorded higher flu activity throughout the country. Those under the age of five and over the age of 65 had the highest flu rates, according to CIDRAP News.

There were 11 pediatric deaths attributable to the flu for the week of February 7, raising the total number to 30 from 18 different states. Four of the deaths were linked to influenza B, two to 2009 H1N1, one to H3N2 and four to undetermined types of influenza A.

In a flu update summary, the CDC announced that the flu generally peaks in January or later during most years. The CDC still believes that the seasonal vaccine is a good match to the circulating strains. Antiviral resistance testing since October 2010 has yet to find that the flu strains present are particularly resistant to Tamiflu or Relenza.