Influenza Activity in the United States Slightly Decreased

Influenza activity has been decreasing in recent weeks, but remains elevated in the United States, according to the CDC.

In the March 15, 2019 FluView update, the CDC reported a slight decrease in the percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories, from the previous week. According to the agency’s preliminary data, 97% of the 10,591 positive specimens indicated Influenza A viruses, and 2.8% of the positive specimens showed Influenza B. Nationally, of the influenza A viruses, H3N2 was reported more frequently than H1N1 in the last 3 weeks.

In addition to virus type, the CDC reported widespread influenza activity in 46 states and Puerto Rico, and Hawaii, Tennessee, Texas and Vermont with regional activity, for the week ending March 9. This indicates a slight decrease over a 2-week period. During this season’s most widespread week to date, ending February 23, 49 states and Puerto Rico reported widespread activity with Hawaii reporting local activity.

Outpatient visits for influenza-like illnesses (ILI) also decreased slightly in the week ending March 9, from 4.7% to 4.5%. Thirty states reported high ILI activity, and 11 states reported moderate ILI activity. New York City, the District of Columbia and 5 states reported low activity. At its highest this season, the rate of outpatient visits for ILI was 5.5%, during the week ending February 16.

Four pediatric deaths were reported in the week ending March 9. Overall, 68 pediatric deaths have been reported since the start of the 2018-2019 flu season.

Cumulatively, a rate of 41.3 laboratory-confirming influenza-associated hospitalizations per 100,000 population was reported in the week ending March 9. The highest hospitalization rate was among adults aged 65 years and older (123.9 per 100,000).

Reference

Centers for Disease Control & Prevention. Weekly U.S. Influenza Surveillance Report: 2018-2019 Influenza Season Week 10 ending March 9, 2019. FluView. https://www.cdc.gov/flu/weekly/index.htm#S1. Updated March 15, 2019. Accessed March 15, 2019.