FluView: A Weekly Influenza Surveillance Report Prepared by the Influenza Division

2018-2019 Influenza Season Week 11 ending March 16, 2019

All data are preliminary and may change as more reports are received.

An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at http://www.cdc.gov/flu/weekly/overview.htm.


Influenza activity remains elevated in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending March 16, 2019:

National and Regional Summary of Select Surveillance Components

HHS Surveillance Regions* Data for current week National data is for the current week
Regional data is for the most recent three weeks

Out-patient ILI Number of jurisdictions reporting regional or widespread activity§ % respiratory specimens positive for flu in clinical laboratories Predominant flu virus reported by public health laboratories
Nation Elevated 49 of 54 26.0% Influenza A(H3)
Region 1 Elevated 5 of 6 19.6% Approximately equal Influenza A(H1N1)pdm09 and Influenza A(H3)
Region 2 Elevated 3 of 4 22.5% Influenza A(H3)
Region 3 Elevated 5 of 6 25.0% Influenza A(H1N1)pdm09
Region 4 Elevated 8 of 8 13.9% Influenza A(H3)
Region 5 Elevated 6 of 6 29.5% Influenza A(H3)
Region 6 Elevated 5 of 5 27.9% Influenza A(H3)
Region 7 Elevated 4 of 4 30.3% Influenza A(H3)
Region 8 Elevated 6 of 6 31.7% Influenza A(H3)
Region 9 Elevated 3 of 5 12.2% Influenza A(H3)
Region 10 Elevated 4 of 4 35.9% Influenza A(H3)

† Elevated means the % of visits for ILI is at or above the national or region-specific baseline
§ Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands