Weekly U.S. Influenza Surveillance Report

CDC's Influenza Division produces a weekly influenza surveillance report, FluView. According to last week's report (Nov 18-24), seasonal influenza activity has increased to levels above baseline in the United States.

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Synopsis:

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:

Viral Surveillance: Influenza A viruses have predominated in the United States since the beginning of July. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.

Virus Characterization: The majority of influenza viruses characterized antigenically and genetically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
Antiviral Resistance: All viruses tested since late May show susceptibility to the antiviral drugs oseltamivir, zanamivir, and peramivir.

Influenza-like Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) increased to 2.3%, which is above the national baseline of 2.2%. Five of 10 regions reported ILI at or above their region-specific baseline level.

ILI State Activity Indictor Map: Two states experienced high ILI activity; three states experienced moderate ILI activity; New York City, the District of Columbia, Puerto Rico and eight states experienced low ILI activity; and 37 states experienced minimal ILI activity.

Geographic Spread of Influenza: The geographic spread of influenza in five states was reported as regional; 16 states reported local activity; the District of Columbia, Puerto Rico, the U.S. Virgin Islands and 28 states reported sporadic activity; and Guam and one state reported no influenza activity.
Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
Influenza-associated Pediatric Deaths: Two influenza-associated pediatric deaths were reported to CDC for week 47.