Influenza (FLU) Update for Week Ending 3-23-19

Influenza (FLU) Update for Week Ending 3-23-19

For week #12 (ending 3-23-19) the CDC reported that Influenza (Flu) activity, which includes diagnosed flu as well as ILI (Influenza-Like-Illness), decreased but was still elevated during Week #12.  The percentage of respiratory specimens testing positive for flu decreased to 22.1% from 26% last week with all 10 Regions reported flu levels above their baseline. Also, the number of hospitalizations from flu continued to increase.  The CDC expects flu and ILI activity to stay at elevated levels into mid-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.  For the fifth week in a row this flu season, Influenza A(H3) was more prevalent nationally and dominant in all the Regions.  Overall, Influenzas A (H1N1), A (H3N2) and Influenza B viruses were co-circulating, with Influenza B cases increasing slightly, a sign typically seen in the spring.

The majority of the flu viruses were genetically similar to the 2018/19 Flu Vaccine, but an increasing amount of the Influenza A(H3N2) viruses are antigenically different from the H3N2 reference virus used in the 2018/19 North American Hemisphere Flu Vaccine.  Changes to the 2019/20 North American Hemisphere Vaccine have been recommended and adopted.

The CDC has published its 2018/19 Flu Season Preliminary Burden Estimates, and from October 1, 2018 through March 23, 2019, and there have been an estimated with 31.2 – 35.9 million flu illnesses, 14.4 – 16.8 million medical visits for flu, 419,000 – 508,000 flu-related hospitalizations, and 28,000 – 46,800 flu deaths.

As part of the CDC’s Epidemic Prediction Initiative (EPI), their forecast as of 3/26/19, is that flu activity is likely to remain elevated through mid-April.  Also, there is about a 95% 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 #12 showed an increase in numbers.

For the most recently reported week, ending March 23, 2019, the CDC reported:
Influenza-like illness (ILI) visits to clinics & other non-hospital facilities decreased to 3.8% (l. w. 4.4%), but remained above the national baseline of 2.2%.  All 10 regions reported ILI at or above their region-specific baselines, with a range of 2.8% to 5.6%. Twenty (20) states reported high ILI activity.

Flu cases, documented by positive flu tests of respiratory specimens, were reported as Widespread in Puerto Rico and 34 states.  Clinical lab testing for influenza was positive for 22.1% of specimens, compared to 26% last week, with a range of 11.5% (Region 9) to 36.7% (Region 10).  All regions were in the double digits, with five (5) at > 20% and two (2) at > 30%.

Influenza A remained the dominant flu for 94.6% of the flu tests reported (last week 96.4%), and the H3N2 subtype remained the dominant Influenza A virus at 68.1% (65.4% last week), as A(H1N1)pdm09 viruses decreased to 31.9% (34.6% l.w.).  The rest of the tests showed 5.4% (3.6% l.w.) tested as Influenza B viruses, with Yamagata at 23.1% and Victoria at 76.9%.  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:  (20 states):  Alabama, Arkansas, Colorado, Indiana, Iowa, Kentucky, Louisiana, Michigan, Missouri, New Mexico, New York, Oklahoma, Oregon, Rhode Island, South Carolina, Texas, Utah, Virginia, Washington, and Wisconsin
Moderate ILI Activity:  (Puerto Rico & 13 states):  Arizona, California, Georgia, Illinois, Kansas, Maine, Maryland, New Jersey, North Carolina, Ohio, Pennsylvania, West Virginia, and Wyoming
Low Activity:  (New York City, Washington D.C., & 7 states):  Connecticut, Idaho, Massachusetts, Minnesota, Mississippi, Nevada, and Vermont
Minimal Activity:  (10 states):  Alaska, Delaware, Florida, Hawaii, Montana, Nebraska, New Hampshire, North Dakota, South Dakota, and Tennessee
Insufficient Data:  the U.S. Virgin Islands

For Flu (positive flu tests):

Widespread Activity:  (Puerto Rico & 34 states):  Alabama, Arizona, Arkansas, California, Connecticut, Delaware, Georgia, Illinois, Indiana, Iowa, Kansas, Maine, Maryland, Massachusetts, Michigan, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Virginia, Washington, Wisconsin, and Wyoming
Regional Activity (14 states):  Colorado, Florida, Idaho, Kentucky, Louisiana, Minnesota, Nebraska, North Dakota, South Dakota, Tennessee, Texas, Utah, Vermont, and West Virginia
Local Activity: (Washington D.C. & 2 states):  Alaska and Hawaii
Sporadic Activity:  the U.S. Virgin Islands
Guam did not report

Other Data:

The Hospitalization rate from Flu increased to 52.5 per 100,000 (last week 47.1/100,000).  Older adults (age > 65 years) had the highest hospitalization rate at 167 per 100,000 (l.w. 146/ ); adults (age 50-64 years) were at 67.4 per 100,000 (l.w. 61/ ); and children (ages 0-4) had 63.6 per 100,000 (last week 59/ ).

As of 3/28/19, the death rate for pneumonia & influenza in adults was at 7.4%, above the epidemic threshold of 7.2% for week #11. Note:  the epidemic threshold number may change from week to week.  Death reports often aren’t reported for data purposes the same week and are typically reported by the CDC a week behind.

There was one (1) pediatric death attributed to flu reported this week and occurred in Week 12, for a total of 77 for this Flu Season.

Flu in Canada, Europe & the World:

According to the Public Health Agency of Canada (PHAC), for Week #12, ending 3/23/19, Influenza was reported in almost all the Regions, though circulation was at greater levels in some Eastern Regions.  The PHAC also reported that Influenza A(H3N2) cases have been increasing since the middle of Jan and represented 72% of the Influenza A subtyping, this week, compared to 64% for last week, though A(H1N1)pdm09 was still the dominant type for this Flu Season as a whole.  Influenza A(H1N1) peaked at the end of December, but a smaller wave of flu cases with A(H3N2) dominating for the past month, has been seen in most Regions of the country.  Meanwhile, very little Influenza B has been identified this season when compared to other seasons.

Widespread Activity in 0 Regions
Localized Activity in 15 Regions:  Alta. (1), Ont. (6), N.S. (3), and N.B. (2),  P.E.I (1), and N.L. (2),
Sporadic Activity in 33 Regions:  B.C. (5), Alta. (4), Sask. (3),  Man. (4), Ont. (1), Que (6), N.B. (5), N.L. (2), N.S. (1), Y.T. (1), and  Nvt. (1)
No Activity Reported in 3 Regions:   Man. (1) and Nvt. (2)

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 #12 (Mar 18 – 24, 2019), for the 45 countries reporting on geographic spread of influenza activity, only 11 had widespread activity, namely in the Northern, Southern, and Western areas of Europe.  The samples taken from those with ILI or ARI (acute respiratory illness) by sentinel primary healthcare sites, decreased to 38% positive for flu viruses, compared with 39% last week.  Those reported with severe acute respiratory infection (SARI) that were tested for flu viruses, resulted in a result of 21% and almost all were Influenza A.  Overall, Influenza A viruses dominated, with more A(H3N2 than A(H1N1)pdm09; with few Influenza B viruses found.  Data from the reporting Member States and areas that reported to the EuroMOMO project indicated that excess mortality had returned to normal levels.

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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