Influenza (FLU) Update for Week Ending 3-16-19

Influenza (FLU) Update for Week Ending 3-16-19

For week #11 (ending 3-16-19) the CDC reported that Influenza (Flu) activity, which includes diagnosed flu as well as ILI (Influenza-Like-Illness), was elevated during Week #11.  The percentage of respiratory specimens testing positive for flu increased slightly to 26% from 25.8% last week, all 10 Regions reported flu levels above their baselines, and the number of hospitalizations from flu continued to increase.  The CDC expects flu and ILI activity to stay at elevated levels into April, however none of the numbers approach last season’s (2017/18) flu severity.

In the samples tested, Influenza A viruses were the largest percentage of viruses.  However, for the fourth week in a row this flu season, Influenza A(H3) was more prevalent nationally and has now dominated all the Regions except Region 1 (CT, ME, MA, NH, RI, VT), which had about equal A(H1N1)pdm09 and A(H3) and Region 3 (Mid-Atlantic), which was dominated by A(H1N1)pdm09.  Overall, Influenzas A (H1N1), A (H3N2) and Influenza B viruses were co-circulating.

The majority of the flu viruses were genetically similar to the 2018/19 Flu Vaccine.

The CDC has published its 2018/19 Flu Season Preliminary Burden Estimates, and from October 1, 2018 through March 16, 2019, and there have been an estimated with 28.5 – 32.8 million flu illnesses, 13.2 – 15.4 million medical visits for flu, 375,000 – 454,000 flu-related hospitalizations, and 25,000 – 41,500 flu deaths.

As part of the CDC’s Epidemic Prediction Initiative (EPI), their forecast as of 3/18/19, is that flu activity is likely to remain elevated through early April.  Also, there is about a 90% chance that this year’s flu season peaked mid-February at a national level, although different areas of the U.S. may differ in their timing.  This link provides info on the EPI prediction:

FirstWatch RIN (Regional Influenza Network):  RIN Alerts for Week #11 repeated a decrease in numbers.

For the most recently reported week, ending March 16, 2019, the CDC reported:
Influenza-like illness (ILI) visits to clinics & other non-hospital facilities decreased slightly to 4.4% (l. w. 4.5%), but remained well above the national baseline of 2.2%.  All 10 regions reported ILI at or above their region-specific baselines, with a range of 3.1% to 7.7%. Twenty-six (26) states reported high ILI activity.

Flu cases, documented by positive flu tests of respiratory specimens, were reported as Widespread in 44 states.  Clinical lab testing for influenza was positive for 26.0% of specimens, compared to 25.8% last week, with a range of 12.2% (Region 9) to 35.9% (Region 10).  All regions were in the double digits, with four (4) at > 20% (1 of them at > 29.0%) and three (3) at > 30%.

Influenza A remained the dominant flu for 96.4% of the flu tests reported (last week 97.2%), and the H3N2 subtype remained the dominant Influenza A virus at 65.4% (61.3% last week), as A(H1N1)pdm09 viruses decreased to 34.6% (38.7% l.w.).  The rest of the tests showed 3.6% (2.8% l.w.) tested as Influenza B viruses, with Yamagata at 20% and Victoria at 80% again.  Typically, Influenza B viruses occur more towards Spring and cause less severe illness.  This pattern is mirrored in much of the world.

More than 99% of the flu viruses tested were found to be sensitive to the antivirals oseltamivir, zanamivir (100%), and peramivir (Tamiflu, Relenza, and Rapivab, respectively).
The CDC recommends treatment with antivirals, as early as possible, for those with confirmed or suspected flu with severe, complicated, or progressive disease, those who are hospitalized, or at high risk for complications of flu.  See this link for a list of those at risk for complications from flu: 

The CDC provides an interactive U.S. map that will link to each state’s public health authorities.  ILI and Flu information and processes, as well as other diseases and public health topics.   This site includes a tremendous amount of information at the State and even Local level.  Find it at this site:

For Influenza-Like Illness:

High ILI Activity:  (26 states):  Alabama, Alaska, Arkansas, Colorado, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, New Jersey, New Mexico, North Carolina, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Utah, Virginia, Washington, and Wisconsin
Moderate ILI Activity:  (12 states):  California, Hawaii, Maine, Maryland, Michigan, Minnesota, Montana, Nevada, New York, Ohio, West Virginia, and Wyoming
Low Activity:  (New York City, Puerto Rico, & 8 states):  Arizona, Connecticut, Idaho, Massachusetts, Nebraska, North Dakota, South Dakota, and Vermont
Minimal Activity:  (4 states):  Delaware, Florida, New Hampshire, and Tennessee
Insufficient Data:  Washington D.C., & the U.S. Virgin Islands

For Flu (positive flu tests): 

Widespread Activity:  (44 states):  Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Utah, Virginia, Washington, Wisconsin, and Wyoming
Regional Activity (Puerto Rico & 4 states):  Nebraska, Tennessee, Texas, and West Virginia
Local Activity: (Washington D.C. & 2 states):  Hawaii and Vermont
Sporadic Activity:  the U.S. Virgin Islands
Guam did not report

Other Data:

The Hospitalization rate from Flu increased to 47.1 per 100,000 (last week 41.3/100,000).  Older adults (age > 65 years) had the highest hospitalization rate at 146 per 100,000 (l.w. 123.9/ ); adults (age 50-64 years) were at 61 per 100,000 (l.w. 54/ ); and children (ages 0-4) had 59 per 100,000 (last week 54.8/ ).  Most hospitalizations, 95.9% (l.w. 95.6%), were caused by Influenza A viruses; 3.4% (l.w. 3.6%) were from Influenza B viruses; 0.3% (the same for 2 weeks) showed co-infection with both Influenza A and B viruses; and 0.5% (same as the last 5 weeks) were not typed for a specific flu virus.

As of 3/14/19, the death rate for pneumonia & influenza in adults was at 7.1%, below the epidemic threshold of 7.3% for week #10 (death reports often aren’t reported for data purposes the same week and are typically reported by the CDC a week behind).

There were another eight (8) pediatric deaths attributed to flu reported this week, occurring in Weeks 4, 8, 9, 10 & 11, for a total of 76 for this Flu Season.

Flu in Canada, Europe & the World:

According to the Public Health Agency of Canada (PHAC), for Week #11, ending 3/16/19, Influenza was reported in almost all the Regions, though circulation was at greater levels in the Eastern Regions.  The PHAC also reported that Influenza A(H3N2) cases have been increasing since the middle of Jan and was at 64% this week of the Influenza A subtyping, compared to 56% for last week, though overall A(H1N1)pdm09 was still the dominant type for this Flu Season as a whole.  Meanwhile, very little Influenza B has been identified this season when compared to other seasons.  The WHO announced that they have made a change to the H1N1 and H3N2 virus strains for the 2019-2020 Flu Vaccine, compared to this year’s vaccine.  This is due to changes in the circulating strains.

Widespread Activity in 0 Regions:
Localized Activity in 19 Regions:  Alta. (2), Man. (1), Ont. (6), Que. (3), N.S. (4), and N.B. (1) and N.L. (2),
Sporadic Activity in 29 Regions:  B.C. (5), Alta. (3), Man. (2), Ont. (1), Que (3), N.B. (6), N.L. (2), P.E.I (1), Nvt. (1), Y.T. (1), and N.W.T. (1) (as reported by PHAC, it adds to 26)
No Activity Reported in 5 Regions:   Man. (2), Nvt. (2), N.W.T (1)

For more specific information see: 
On flu activity

Canadian Flu Information: 

General Page for Canadian Flu Watch Surveillance with links to different components:

About the Canadian Influenza Activity Surveillance System:

According to the European Center for Disease Prevention & Control (ECDC), for Week #11 (Mar 11 – 17, 2019), Influenza activity remained widespread in a third (1/3) of the European Region, namely the Northern, Southern, and Western areas.  The samples taken from those with ILI or ARI (acute respiratory illness) by sentinel primary healthcare sites, decreased to 34% positive for flu viruses, compared with 42% last week.  A slight majority of circulating viruses remained Influenza A, with A(H1N1)pdm09 rather than A(H3N2), with very few Influenza B viruses found.  Data from 24 Member States reported a continued decrease in the excess mortality, but was still seen in those aged >65 and the 15 – 64 age group.

For more information see:

WorldThe World Health Organization (WHO) provides info on Influenza in Member Countries here:

First Responder Specific Information

There are many websites that may be helpful in planning and managing seasonal flu within First Responder organizations.  A few of those websites are included here:  

NIOSH on Flu for Employers/Employees:

Protection from Flu:  

Weekly Flu Map: 

World Map Showing Flu & Other Infectious Diseases:

Other Actions First Responders Should Consider

  • First Responders should be vaccinated for Flu each season to prevent getting flu themselves, taking it home to family members, or transmitting it to patients in their care. Family members and patients may be at increased risk of complications from flu.
  • Perform proper hand hygiene including frequent handwashing and the use of hand sanitizers in general, and particularly when providing patient care or after touching surfaces.
  • Masks (N95 or N100) should be used in the presence of patients with cough and/or fever; preferably before being within 6 feet of the patient. This becomes even more important if droplet producing procedures are being performed (i.e. suctioning, nebulizer treatments, BVM, intubation).
  • Care should be taken to avoid touching your own face and mucous membranes (eyes, mouth, nose) since the flu virus is frequently found on surfaces such as door knobs, writing & recording tools (pens and tablets), cot and equipment handles, phones, light switches, as well as clothing, bed clothes, etc.
  • Report signs/symptoms of flu to your physician or other appropriate provider for early assessment and care. Alert your employer per policy.
  • Cough and sneeze into your sleeve, if a tissue is not available, and not onto your hands. Watch this Youtube video for a humorous but educational approach on the subject.
  • Stay away from others if you are sick.
  • Be aware of your exposure risk and history to prevent exposing others. Take extra precautions or avoid those with immunocompromise, when possible, if you have a known or likely exposure.
  • Antivirals may be indicated for the treatment of flu, particularly for those in high risk groups, those who are hospitalized or have severe, complicated or progressing flu. Those that present with 48 hours of the onset of symptoms may also be given antivirals, based on PCP judgement but make sure the practitioner is aware of their First Responder Role.  See

And, for consideration when looking at yourself, your family and friends, or your patients, consider the following information regarding complications of flu:

Flu is much more worrisome for the very young and the elderly, as well as those who fit into one of the high risk categories see this link for the list: . Signs of ILI/Flu in this group requires careful assessment to rule out complications and these groups are much more likely to need medical oversight to assure adequate care.  Young children and those over 65 are typically at greater risk for complications, hospitalization, and even death.

Consideration should be given to perhaps monitoring these groups more closely, with inclination for more comprehensive assessment and transport for further evaluation, when presented with possible flu and any signs of complications.

Complications of flu, sometimes requiring hospitalization and even leading to death, tend to occur after the person has begun to get better from the flu and then appears to relapse.  EMS personnel may want to look more closely at those patients when the call is not about the initial signs and symptoms of flu, but about increasing or different signs that have appeared, often from five days to two weeks after the initial flu symptoms began.

A study was published by the Institute for Clinical Evaluative Sciences in NEJM (New England Journal of Medicine).  See details below:

Study confirms importance of flu vaccination

Image courtesy of ICES/PHO

“The researchers add that patients should not delay medical evaluation for heart symptoms particularly within the first week of an acute respiratory infection.”  (Lisa Schnirring, News Editor:  CIDRAP News ;Jan 25, 2018)

For more information on Influenza and the Heart Attack Study, please see the link below.

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