CDC Flu Update: Activity is Low But Expected to Increase in Coming Weeks

According to the CDC's FluView report for the week ending Nov. 5, 2016, flu activity is low overall in the continental United States. Influenza A (H3) viruses were most commonly reported during week 44. 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 5, the proportion of people seeing their healthcare provider for influenza-like illness (ILI) was 1.4%. This is below the national baseline of 2.2%. All 10 regions reported ILI below their region-specific baseline levels.

Puerto Rico experienced moderate ILI activity. One state (Georgia) experienced low ILI activity. New York City and 49 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 one state (New Hampshire). Local flu activity was reported by six states (California, Hawaii, Maine, Massachusetts, Oklahoma, and Oregon). Sporadic flu activity was reported by the District of Columbia, the U.S. Virgin Islands, and 39 states (Alabama, Alaska, Arizona, Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming). No activity was reported by 4 states (Illinois, Nebraska, Rhode Island, 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 5.6% for the week ending October 22, 2016 (week 42). This percentage is below the epidemic threshold of 6.6% for week 42 in the NCHS Mortality Surveillance System.

No influenza-associated pediatric deaths were reported to CDC this week.

Nationally, the percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories during the week ending November 5 was 2.2%.

Regional clinical laboratory data percentages ranged from 0.2% to 4.2% for the most recent three weeks.

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 5, 31 (91.2%) of the 34 influenza-positive tests reported to CDC by public health laboratories were influenza A viruses and 3 (8.8%) were influenza B viruses. Of the 23 influenza A viruses that were subtyped, 18 (78.3%) were H3 viruses and 5 (21.7%) were (H1N1)pdm09 viruses.

For viruses collected between May 22–November 5, 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 October 1, 2016, CDC tested 26 specimens (0 influenza A (H1N1)pdm09, 16 influenza A (H3N2), and 10 influenza B viruses) for resistance to the neuraminidase inhibitors antiviral drugs. None of the tested viruses were found to be resistant to either oseltamivir, zanamivir, or peramivir.

Source: CDC