Weekly U.S. Influenza Surveillance ReportCDC's Influenza Division produces a weekly influenza surveillance report, FluView. According to this week's report (Dec 2- 8), seasonal influenza activity remained at the national baseline level (2.2%) in the United States.
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:
- Viral Surveillance: Influenza A viruses have predominated in the United States since the beginning of October. The percentage of respiratory specimens testing positive for influenza in clinical laboratories remains 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 show susceptibility to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir).
- Influenza-like Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) remained at 2.2%, which is at 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: One state experienced high ILI activity; Puerto Rico and four states experienced moderate ILI activity; New York City, the District of Columbia and nine states experienced low ILI activity; and 36 states experienced minimal ILI activity.
- Geographic Spread of Influenza: The geographic spread of influenza in three states was reported as widespread; 10 states reported regional activity; 21 states reported local activity; the District of Columbia, Puerto Rico, the U.S. Virgin Islands and 16 states reported sporadic activity; and Guam did not report.
- Influenza-associated Hospitalizations A cumulative rate of 1.9 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
- 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: One influenza-associated pediatric death was reported to CDC for week 49.