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

2018-2019 Influenza Season Week 49 ending December 8, 2018

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 in the United States remained slightly elevated. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate, with influenza A(H1N1)pdm09 viruses reported most commonly by public health laboratories since September 30, 2018. Below is a summary of the key influenza indicators for the week ending December 8, 2018:

National and Regional Summary of Select Surveillance Components

HHS Surveillance Regions* Data for current weekPredominant flu virus reported by public health laboratories 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
Nation Elevated 13 of 54 3.6% Influenza A(H1N1)pdm09
Region 1 Elevated 4 of 6 2.9% Approximately equal Influenza A(H1N1)pdm09 and A(H3)
Region 2 Elevated 1 of 4 2.2% Influenza A(H1N1)pdm09
Region 3 Normal 0 of 6 1.6% Influenza A(H1N1)pdm09
Region 4 Elevated 3 of 8 8.1% Approximately equal Influenza A(H1N1)pdm09 and A(H3)
Region 5 Normal 0 of 6 1.8% Influenza A(H1N1)pdm09
Region 6 Normal 1 of 5 3.5% Influenza A(H1N1)pdm09
Region 7 Elevated 0 of 4 2.7% Influenza A(H1N1)pdm09
Region 8 Elevated 0 of 6 3.5% Influenza A(H1N1)pdm09
Region 9 Normal 3 of 5 5.5% Influenza A(H1N1)pdm09
Region 10 Normal 1 of 4 2.1% Influenza A(H1N1)pdm09

† 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
‡ National data are for current week; regional data are for the most recent three weeks