Weekly U.S. Influenza Surveillance Report | Seasonal Influenza (Flu) | CDC

Weekly U.S. Influenza Surveillance Report | Seasonal Influenza (Flu) | CDC

2018-2019 Influenza Season Week 41 ending October 13, 2018

Synopsis:

Influenza activity in the United States remains low. 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 during the most recent three weeks. The first influenza-associated pediatric death occurring during the 2018-2019 season was reported this week. Below is a summary of the key influenza indicators for the week ending October 13, 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) remained low at 1.4%, which is below the national baseline of 2.2%. All regions reported ILI below their region-specific baseline level.
• ILI State Activity Indictor Map: New York City, the District of Columbia, and 49 states experienced minimal ILI activity, and Puerto Rico and one state had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam and two states was reported as local activity; the District of Columbia, the U.S. Virgin Islands and 40 states reported sporadic activity; eight states reported no activity; and Puerto Rico did not report.
• 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 that occurred during the 2018-2019 season was reported to CDC.