CDC Flu Update: Low Activity is Holding Steady

According to the CDC's FluView report for the week ending Nov. 12, 2016, flu activity is low overall in the continental United States. Influenza A (H3) viruses were most commonly reported during week 45. 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 Nov. 12, the proportion of people seeing their health care provider for influenza-like illness (ILI) was 1.6%. This is below the national baseline of 2.2%. One region (Region 4) reported ILI at 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.

Widespread influenza activity was reported by Guam. Regional influenza activity was reported by Puerto Rico, the U.S. Virgin Islands, and one state (New Hampshire). Local flu activity was reported by five states (Hawaii, Maryland, Massachusetts, Oklahoma, and Oregon). Sporadic flu activity was reported by the District of Columbia, and 40 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming). No activity was reported by four states (Nebraska, Rhode Island, Tennessee, and Vermont). 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 5.4% for the week ending October 29, 2016 (week 43). This percentage is below the epidemic threshold of 6.7% for week 43 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 12 was 1.7%.

Regionally, the three week average percent of specimens testing positive for influenza in clinical laboratories ranged from 0.2% to 5.9%.

The most frequently identified influenza virus type reported by public health laboratories during the week ending November 5 was influenza A viruses, with influenza A (H3) viruses predominating.  During the week ending November 12, 34 (97.1%) of the 35 influenza-positive tests reported to CDC by public health laboratories were influenza A viruses and 1 (2.9%) was an influenza B virus. Of the 31 influenza A viruses that were subtyped, 30 (96.8%) were H3 viruses and 1 (3.2%) was a (H1N1)pdm09 virus.

For viruses collected between May 22–November 12, 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 53 specimens (6 influenza A (H1N1)pdm09, 33 influenza A (H3N2), and 14 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