CDC Flu Update: Activity Increasing Slightly

According to the CDC's FluView report for the week ending Nov. 19, 2016, flu activity increased slightly, but remains low overall in the continental United States. Influenza A (H3) viruses were most commonly reported during week 46. While the timing of influenza activity varies and is unpredictable, flu activity is expected to increase in the coming weeks. CDC recommends that everyone 6 months of age and older get an annual flu vaccine before the end of October, or as soon as possible after October.

For the week ending November 19, the proportion of people seeing their healthcare provider for influenza-like illness (ILI) was 1.6%. This is below the national baseline of 2.2%. Two regions (Region 2 and 4) reported ILI at or above their region-specific baseline level.

Puerto Rico experienced high ILI activity. Two states (Georgia and Oklahoma) experienced low ILI activity. New York City and 48 states experienced minimal ILI activity. The District of Columbia did not have sufficient data to calculate an activity level. ILI activity data indicate the amount of flu-like illness that is occurring in each state.

Regional influenza activity was reported by Guam, Puerto Rico, and the U.S. Virgin Islands. Local flu activity was reported by 11 states (Alabama, Connecticut, Hawaii, Maine, Massachusetts, New Hampshire, North Carolina, Oklahoma, Oregon, Texas, and Washington). Sporadic flu activity was reported by the District of Columbia and 36 states (Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, New York, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Utah, Vermont, Virginia, West Virginia, Wisconsin, and Wyoming). No activity was reported by 3 states (Nebraska, Rhode Island, and Tennessee). Geographic spread data show how many areas within a state or territory are seeing flu activity.

Influenza-associated hospitalization data from the Influenza Hospitalization Surveillance Network (FluSurv-NET) for the 2016-2017 influenza season will be updated weekly starting later this season.

The proportion of deaths attributed to pneumonia and influenza (P&I) was 5.6% for the week ending November 5, 2016 (week 44). This percentage is below the epidemic threshold of 6.8% for week 44 in the NCHS Mortality Surveillance System.

No influenza-associated pediatric deaths for the 2016-2017 season have been reported to CDC.

Nationally, the percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories during the week ending November 19 was 2.7%.

Regionally, the three week average percent of specimens testing positive for influenza in clinical laboratories ranged from 0.3% to 7.4%.

The most frequently identified influenza virus type reported by public health laboratories during the week ending November 19 was influenza A viruses, with influenza A (H3) viruses predominating.   During the week ending November 19, 73 (97.3%) of the 75 influenza-positive tests reported to CDC by public health laboratories were influenza A viruses and 2 (2.7%) were influenza B viruses. Of the 60 influenza A viruses that were subtyped, 57 (95.0%) were H3 viruses and 3 (5.0%) were (H1N1)pdm09 viruses.

One human infection with a novel influenza A virus was reported by the state of Iowa.  The person was infected with an influenza A (H1N2) variant virus.

For viruses collected between May 22–November 19, 2016, antigenic and/or genetic characterization shows that the majority of the tested viruses remain similar to the recommended components of the 2016-2017 Northern Hemisphere vaccines.

Since Oct. 1, 2016, CDC tested 91 specimens (8 influenza A (H1N1)pdm09, 67 influenza A (H3N2), and 16 influenza B viruses) for resistance to the neuraminidase inhibitors antiviral drugs. None of the tested viruses were found to be resistant to oseltamivir, zanamivir, or peramivir.

Source: CDC