Friday, January 11, 2019

CDC FluView Week 1 & First In-Season Estimate Of Flu Burden


The CDC has released both their standard Friday FluView report along with their first ever in-season Estimate of Flu Illnesses, Medical Visits, and Hospitalizations - both of which indicate that most of the nation is now well into the winter flu season.

First a snippet from a much larger FluView report.

2018-2019 Influenza Season Week 1 ending January 5, 2019

All data are preliminary and may change as more reports are received.

An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at,

Influenza activity remains elevated in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending January 5, 2019:
Viral Surveillance: The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories decreased slightly. Influenza A viruses have predominated in the United States since the beginning of October. Influenza A(H1N1)pdm09 viruses have predominated in most areas of the country, however influenza A(H3) viruses have predominated in the southeastern United States (HHS Region 4).
  • Virus Characterization: The majority of influenza viruses characterized antigenically and genetically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
  • Antiviral Resistance: All viruses tested show susceptibility to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir).
Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) decreased from 4.0% to 3.5%, but remains above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
  • ILI State Activity Indictor Map: New York City and 15 states experienced high ILI activity; 12 states experienced moderate ILI activity; the District of Columbia, Puerto Rico and eight states experienced low ILI activity; and 15 states experienced minimal ILI activity.
Geographic Spread of Influenza: The geographic spread of influenza in 30 states was reported as widespread; Puerto Rico and 17 states reported regional activity; two states reported local activity; the District of Columbia, the U.S. Virgin Islands and one state reported sporadic activity; and Guam did not report.
Influenza-associated Hospitalizations A cumulative rate of 9.1 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (22.9 hospitalizations per 100,000 population).
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: Three influenza-associated pediatric deaths were reported to CDC during week 1.

While this year's flu season hasn't mirrored the meteoric rise we saw in last year's very severe H3N2 season, we are none-the-less seeing significant flu illness, medical visits and hospitalizations.

This from the CDC's Media site:

CDC Provides First In-Season Estimates of Flu Illnesses, Medical Visits, and Hospitalizations
Media Statement
For Immediate Release: Friday, January 11, 2019
Contact: Media Relations
(404) 639-3286

According to new data released by CDC, so far during the 2018-2019 season between about 6 and 7 million people have been sick with flu, up to half of those people have sought medical care for their illness, and between 69,000 and 84,000 people have been hospitalized from flu. This is the first time these estimates— which cover the period from October 1, 2018 through January 5, 2019— are being provided during the flu season. CDC has estimated the burden of flu since 2010.

These data are derived using the same mathematical model used to generate previous end-of-season estimates. Calculations are based on adjusted rates of laboratory-confirmed, influenza-associated hospitalizations collected through a surveillance network that covers approximately 8.5% of the U.S. population, or about 27 million people.

Based on this methodology, CDC estimates that as of Jan. 5:
  • 6.2 to 7.3 million people have been sick with flu,
  • 2.9 to 3.5 million people have been to the doctor because of flu, and
  • 69,300 to 83,500 people have been hospitalized because of flu
These estimates are cumulative and will be updated over the course of the annual flu season on Fridays.

CDC’s weekly FluView reports when and where influenza activity is occurring, which influenza viruses are circulating and reports the impact influenza is having on hospitalizations and deaths in the United States based on data collected from eight different surveillance systems. Data presented in FluView allow CDC to track flu activity, but do not provide exact case counts, with the exception of flu-associated pediatric deaths and human infections with novel influenza A viruses, which are nationally notifiable.

Each year seasonal flu places a significant burden on the health of people in the United States. These new in-season estimates fill out the picture of the burden of flu in the United States.

CDC continues to recommend flu vaccination as the best way to reduce the risk of flu and its potentially serious complications, including death in children. People who are very sick or who are at high risk of serious flu complications and get flu symptoms should see a health care provider early in their illness for possible treatment with a flu antiviral drug.

In addition to vaccination and appropriate use of antiviral drugs, CDC recommends everyday preventive actions to help stop the spread of germs. If you are sick with flu-like illness, CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. Cover your nose and mouth with a tissue when you cough or sneeze and wash your hands often with soap and water. Avoid touching your eyes, nose and mouth as germs spread this way. Clean and disinfect surfaces and objects that may be contaminated with germs like flu.

The CDC also introduced their new FluSight Forecasting system this week, which currently projects:

Current Flu Forecasting:

Each week during the influenza season, CDC displays the forecasts received through the Epidemic Prediction Initiative(EPI). This week forecasts indicate
  • Flu activity will likely increase over the next four weeks and the highest flu activity will likely occur in the next two months.
  • There is about a 70% chance that the highest flu activity for this season will occur by the end of January and a greater than 95% chance that the highest flu activity will occur by the end of February.
While ideally you've already gotten the flu shot for this year, with another 8 to 12 weeks of flu season ahead, it still makes sense to get one. And flu shot or not, now is the time to practice good fly hygiene - cover your coughs and sneezes, stay home if you are sick, and wash or sanitize your hands often.

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