Weekly U.S. Influenza Surveillance Report | CDC

Weekly U.S. Influenza Surveillance Report | CDC

2018-2019 Influenza Season Week 2 ending January 12, 2019

Synopsis:

Influenza activity remains elevated in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending January 12, 2019:

• Viral Surveillance: The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories decreased slightly. Influenza A viruses have predominated in the United States since the beginning of October. Influenza A(H1N1)pdm09 viruses have predominated in most areas of the country, however influenza A(H3) viruses have predominated in the southeastern United States (HHS Region 4).
• 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: None of the viruses tested were associated with highly reduced inhibition by any of the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir).
• Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) decreased from 3.5% to 3.1%, but remains above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
• ILI State Activity Indictor Map: Nine states experienced high ILI activity; New York City and 13 states experienced moderate ILI activity; 10 states experienced low ILI activity; and the District of Columbia, Puerto Rico and 18 states experienced minimal ILI activity.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam and 30 states was reported as widespread; Puerto Rico and 16 states reported regional activity; three states reported local activity; and the District of Columbia, the U.S. Virgin Islands and one state reported sporadic activity.
• Influenza-associated Hospitalizations A cumulative rate of 12.4 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (31.9 hospitalizations per 100,000 population).
• 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: Three influenza-associated pediatric deaths were reported to CDC during week 2.