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

2018-2019 Influenza Season Week 47 ending November 24, 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 increased slightly. The increase in the percentage of patient visits for ILI may be influenced in part by a reduction in routine healthcare visits during the Thanksgiving holidays, as has occurred in previous seasons. 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 November 24, 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 5 of 54 2.4% Influenza A(H1N1)pdm09
Region 1 Normal 2 of 6 1.8% Influenza A(H1N1)pdm09
Region 2 Elevated 0 of 4 1.3% Influenza A(H1N1)pdm09
Region 3 Normal 0 of 6 0.6% Influenza A(H1N1)pdm09
Region 4 Elevated 1 of 8 5.4% Influenza A(H1N1)pdm09
Region 5 Normal 0 of 6 1.6% Influenza A(H1N1)pdm09
Region 6 Normal 0 of 5 2.0% Influenza A(H1N1)pdm09
Region 7 Elevated 0 of 4 1.7% Influenza A
Region 8 Elevated 1 of 6 1.6% Influenza A(H1N1)pdm09
Region 9 Elevated 0 of 5 2.1% Influenza A(H1N1)pdm09
Region 10 Normal 1 of 4 1.5% Influenza A

† 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