CDC

During week 2 (January 8-14, 2017), influenza activity increased in the United States.

• Viral Surveillance: The most frequently identified influenza virus subtype reported by public health laboratories during week 2 was influenza A (H3). The percentage of respiratory specimens testing positive for influenza in clinical laboratories increased.
• 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.
• Influenza-associated Hospitalizations: A cumulative rate for the season of 10.2 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 3.3%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline levels. New York City and six states experienced high ILI activity; Puerto Rico and eight states experienced moderate ILI activity; 14 states experienced low ILI activity; 22 states experienced minimal ILI activity, and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 29 states was reported as widespread; Guam and 17 states reported regional activity; the District of Columbia and four states reported local activity; and the U.S. Virgin Islands reported sporadic activity.

Neuraminidase Inhibitor Resistance Testing Results on Samples Collected Since October 1, 2016

	Oseltamivir		Zanamivir		Peramivir
	Virus Samples tested (n)	Resistant Viruses, Number (%)	Virus Samples tested (n)	Resistant Viruses, Number (%)	Virus Samples tested (n)	Resistant Viruses, Number (%)
Influenza A (H1N1)pdm09	59	0 (0.0)	59	0 (0.0)	59	0 (0.0)
Influenza A (H3N2)	385	0 (0.0)	385	0 (0.0)	319	0 (0.0)
Influenza B	101	0 (0.0)	101	0 (0.0)	101	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 viruses and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at http://www.cdc.gov/flu/antivirals/index.htm.