CDC Flu Update: Sporadic Activity Continues

According to this week’s FluView report, overall flu activity remains low nationally although small increases in flu activity were reported. Eight states and Guam are now reporting regional or local flu activity (Connecticut, Kentucky, Maryland, Massachusetts, New Hampshire, North Dakota, Oregon, and Texas). That means those states are seeing outbreaks of flu and laboratory-confirmed flu in at least one or less than half of the regions of the state, respectively. However 40 states, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands continue to report only sporadic flu activity, which means those states are seeing small numbers of flu or one laboratory confirmed flu outbreak. Influenza A(H1N1)pdm09 viruses have been the most commonly identified flu viruses since September 30, 2018.

An annual flu vaccine is the best way to protect against influenza and its potentially serious complications. There are many benefits to vaccination, including reducing the risk of flu illness, doctor’s visits, hospitalization, and even death in children. CDC recommends that everyone 6 months and older get vaccinated now. Below is a summary of the key flu indicators for the week ending November 3, 2018:

Influenza-like Illness Surveillance: For the week ending November 3 (week 44), the proportion of people seeing their health care provider for influenza-like illness (ILI) was 1.8% and remains below the national baseline of 2.2%. One of 10 regions (Region 7) reported a proportion of outpatient visits for ILI at or above their region-specific baseline level. Additional ILINet data, including national, regional, and select state-level data for the current and previous seasons, can be found at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.
Influenza-like Illness State Activity Indicator Map: One state (Georgia) experienced moderate ILI activity. Three states (Alabama, Louisiana, and Missouri) experienced low ILI activity. New York City, the District of Columbia, Puerto Rico and 46 states experienced minimal ILI activity. Additional data, including data for previous seasons, can be found at https://gis.cdc.gov/grasp/fluview/main.html.

Geographic Spread of Influenza Viruses: Regional influenza activity was reported by two states (Maryland and Texas). Local influenza activity was reported by Guam and 6 states (Connecticut, Kentucky, Massachusetts, New Hampshire, North Dakota, and Oregon). Sporadic activity was reported by the District of Columbia, Puerto Rico, the U.S. Virgin Islands and 40 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Maine, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming). No influenza activity was reported by 2 states (Mississippi and Virginia).
Geographic spread data show how many areas within a state or territory are seeing flu activity. Additional data are available at: https://gis.cdc.gov/grasp/fluview/FluView8.html.

Flu-Associated Hospitalizations:
Reporting of influenza-associated hospitalization data from the Influenza Hospitalization Surveillance Network (FluSurv-NET) for the 2018-2019 influenza season will begin later this season.
Additional data, including hospitalization rates during previous influenza seasons, can be found at http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.

Mortality Surveillance:
The proportion of deaths attributed to pneumonia and influenza (P&I) was 5.4% during the week ending October 27, 2018 (week 43). This percentage is below the epidemic threshold of 6.1% for week 43 in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
Additional P&I mortality data for current and past seasons and by geography (national, HHS region, or state) are available at https://gis.cdc.gov/grasp/fluview/mortality.html.

Pediatric Deaths:
No influenza-associated pediatric deaths were reported to CDC during week 44. A total of two influenza-associated pediatric deaths have been reported for the 2018-19 season.
Additional information on influenza-associated pediatric deaths reported during past seasons, including basic demographics, underlying conditions, bacterial co-infections, and place of death is available on FluView Interactive at: https://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html. More detailed information about pediatric deaths reported during the current season will be available later in the season.

Laboratory Data:
Nationally, the percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories during the week ending November 3 was 0.9%. Regionally, the three week average percent of specimens testing positive for influenza in clinical laboratories ranged from 0.2% to 5.2%. During the week ending November 3, of the 155 (0.9%) influenza-positive tests reported to CDC by clinical laboratories, 115 (74.2%) were influenza A viruses and 40 (25.8%) were influenza B viruses. The most frequently identified influenza virus type reported by public health laboratories was influenza A(H1N1)pdm09 virus. During the week ending November 3, 42 (91.3%) of the 46 influenza-positive tests reported to CDC by public health laboratories were influenza A viruses and 4 (8.7%) were influenza B viruses. Of the 36 influenza A viruses that were subtyped, 4 (11.1%) were H3N2 viruses and 32 (88.9%) were (H1N1)pdm09 viruses. The majority of the influenza viruses collected from the United States during May 20 through November 3, 2018 were characterized antigenically and genetically as being similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses. None of the viruses tested from May 20-November 3, 2018 were found to be resistant to oseltamivir, zanamivir, or peramivir. Antiviral resistance data will be updated weekly starting later in the season.

Source: CDC