Wicked Flu Season: Are Boomers More Susceptible to H3N2?

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This year’s flu has been reported as being particularly difficult but has not reached “pandemic” level, however, the number of people going to see their doctor or heading to the emergency room for flu-like symptoms this season is the highest since the swine flu pandemic of 2009.

The United States experiences epidemics of seasonal flu each year. In the United States, flu viruses are most common during the fall and winter months. Influenza activity often begins to increase in October and November. Most of the time flu activity peaks between December and February and can last as late as May. CDC monitors certain key flu indicators (for example, outpatient visits of influenza-like illness (ILI), the results of laboratory testing and reports of flu hospitalizations and deaths). When these indicators rise and remain elevated for a number of consecutive weeks, “flu season” is said to have begun. Usually ILI increases first, followed by an increase in flu-associated hospitalizations, which is then followed by increases in flu-associated deaths.

Out of every 100,000 hospitalizations in the U.S., 22.7 were for the flu in the first week in January. According to the CDC, the number had doubled from the week before. During the severe flu season that ended in 2015, rates of hospitalizations reached 29.9 for every 100,000.

The exact number of flu illnesses that occur each season is not known because flu is not a reportable disease and not everyone who gets sick with the flu seeks medical care or gets tested. CDC estimates the total number of flu-associated hospitalizations in the United States. While CDC’s flu surveillance systems, such as FluSurv-NET, monitor rates of flu-associated hospitalizations in the United States, flu surveillance has limitations because most surveillance systems only capture portions of the U.S. population and in some cases can under-report severe illness, including flu hospitalizations. That is why CDC also uses mathematical modeling to fill in the picture of the disease burden. Since 2010, CDC estimates that flu has resulted in between 140,000 and 710,000 hospitalizations each year.

As of this writing, the most frequently identified influenza virus subtype reported by public health laboratories during week 3 was influenza A(H3). The percentage of respiratory specimens testing positive for influenza in clinical laboratories slightly increased.

Detailed statistics from the CDC show that during week 3 (January 14-20, 2018), influenza activity increased in the United States.

Recent disaster events in Texas, Puerto Rico, Florida, the US Virgin Islands and elsewhere may also contribute to the spread of influenza activity:  Widespread influenza activity was reported by Puerto Rico and 49 states. This is the first time in the 13 years of the CDC’s current flu-tracking system that the entire continental US has widespread flu activity.

CDC Map of flu reach week 3Seniors aged 65 and older are being hospitalized more than any other age group, according to the Centers for Disease Control and Prevention’s latest data. And as of January 20, 37 children or infants had died because of flu.

So far, more than 86,000 people have confirmed cases of the flu, and the number of children who have died from the virus is now at 37. While the elderly are getting hit the hardest, the CDC informs us that Baby Boomers, 50 to 64-years-old, are seeing high levels of hospitalization.

While there are multiple reasons for higher rates of hospitalization, chief among them may be the vaccination level is not as high in the Boomer group and they may be more susceptible to the circulating H1N1 virus.

A group of Canadian researchers pose a differently theory related to “imprinting.” While past exposure to influenza A viruses often builds immunity to similar, and sometimes different, strains of the virus, researchers of McMaster University and the Université de Montréal are calling for more attention to exceptions to that rule in a joint study.

New data analysis suggests that people born at the time of the 1957 H2N2 or Asian Flu pandemic were at a higher risk of dying during the 2009 H1N1 Swine Flu pandemic as well as the resurgent H1N1 outbreak in 2013-2014. And it is not the first time this has happened.

“Reported situations in which previous influenza virus exposures have enhanced susceptibility are rare and poorly understood,” said Matthew Miller, senior author of the paper, an assistant professor of biochemistry and biomedical sciences at McMaster University, and senior researcher with its Michael G. DeGroote Institute of Infectious Disease Research.

Cold or Flu chart“This study’s results have important implications for pandemic risk assessment and should inform laboratory studies aimed at uncovering what’s responsible for this effect.”

Read the study press release here and related study results at mBio, published by the American Society for Microbiology.

The best way to prevent the flu is to get the flu shot, and it’s still not too late. Wash your hands for at least 30 to 45 seconds, cover your cough with your arm, not your hands, and stay home if you’re sick.

According to the CDC, most people with the flu have mild illness and do not need medical care or antiviral drugs. If you get sick with flu symptoms, in most cases, you should stay home and avoid contact with other people except to get medical care.

If, however, you have symptoms of flu and are in a high-risk group, or are very sick or worried about your illness, contact your health care provider (doctor, physician assistant, etc.). There are drugs your doctor may prescribe for treating the flu called “antivirals.” These drugs can make you better faster and also may prevent serious complications.

The emergency warning signs of flu sickness

In children

  • Fast breathing or trouble breathing
  • Bluish skin color
  • Not drinking enough fluids
  • Not waking up or not interacting
  • Being so irritable that the child does not want to be held
  • Flu-like symptoms improve but then return with fever and worse cough
  • Fever with a rash

In addition to the signs above, get medical help right away for any infant who has any of these signs:

  • Being unable to eat
  • Has trouble breathing
  • Has no tears when crying
  • Significantly fewer wet diapers than normal

In adults

  • Difficulty breathing or shortness of breath
  • Pain or pressure in the chest or abdomen
  • Sudden dizziness
  • Confusion
  • Severe or persistent vomiting
  • Flu-like symptoms that improve but then return with fever and worse cough
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