Posts Tagged ‘centers for disease control’

Flu Activity Picks Up Nationwide

Last week, the Center for Disease Control (CDC) issued this press release, followed by immediate headlines. “Flu outbreak leaves thousands in New York sick”, “CDC says 2012-2013 influenza season to be the worst since 2009”, “Influenza season hits severe spike early nationwide”. Sounds horrible, doesn’t it? Many of us secretly fear a killer pandemic (how else to explain zombie movies?), so these headlines get readers. However, much of your “flu” knowledge might be wrong.  What is it, do you have it, how bad is it, should you get vaccinated, and could it really become a dreaded disaster? Everyone gets influenza sooner or later, so let’s try to understand it better.

An influenza virus seen through an electronic microscope.  Photo by  Sanofi Pasteur.

An influenza virus seen through an electronic microscope. Photo by Sanofi Pasteur.

Influenza vs Flu

Influenza is a big dysfunctional family of viruses that cause fever, muscle aches, headache, general blahs, dry cough, sore throat, and runny nose (kids add on ear aches, nausea, and vomiting).  Influenza makes us suffer for 3—7 days, although cough and malaise can last 2 weeks or more. The problem? Lots of non-influenza viruses cause similar symptoms. Patients and doctors label them as “the flu”, but they’re not actually influenza. Even published reports interchange the words when discussing influenza.

24-hour flu = not influenza. Nausea and diarrhea = not influenza. Sore throat, stuffed up nose, no fever = not influenza. Real influenza lasts longer, has prominent fever and cough, and minimal stomach symptoms (although 1/3rd of people are asymptomatic despite infection – hurrah for immune systems!). A lab test is the only way to diagnose influenza accurately, but unless it changes treatment, why pay for it?

How Dangerous is Influenza?

Do people die from the flu? Trick question! If it isn’t really influenza, chances of major problems are minimal. With real influenza, the chronically ill, the elderly, and very young children (<2) definitely have increased risk of death, but it’s often not the virus itself that kills. Influenza increases the likelihood of pneumonia, dehydration, and worsening of medical problems like heart failure, lung disease, asthma, or diabetes. These complications are the main reason for hospitalization and death.

Influenza Numbers (With Caveats)

The science behind influenza is grayer than other areas of medicine. Epidemiologists never know for sure how many people get true influenza. They estimate from things like increased doctor visits for “influenza-like-illness” (ILI) – one reason for last week’s press release. They look at “laboratory-confirmed influenza-associated hospitalizations” – when ILI is bad enough to need the hospital, a lab test is usually done.  They estimate death rates by combining statistics on respiratory illness deaths with statistics on lab results. Influenza science isn’t bad or incorrect – it just has limits. With that understanding, here are some numbers:

  • Influenza-associated deaths in the US vary annually from 3,000 to 49,000. For comparison sake, in 2009 there were 31,347 gun-related deaths, 41,592 poisoning deaths, and 34,485 motor vehicle deaths.
  • About 8.5% of all pneumonia related deaths and 2.1% of all heart and lung deaths are associated with influenza.
  • About 200,000 people in the US are hospitalized each year for problems associated with influenza.
  • People lose 1-5 days of work from each episode of influenza – lots of lost income and stressed co-workers.


Epidemics and Pandemics – Because I Need Something Scary in This Post!

An epidemic occurs when new cases of a disease are much greater than expected. Pandemics are just epidemics spreading across large areas. Influenza epidemics and pandemics usually arise when a new member of the influenza virus family appears, often spreading to humans from an animal. The danger from a new virus depends on 1) how easily it spreads and 2) how badly it affects the body. The Spanish Flu of 1918 killed 50 million people in one year. It spread easily from person to person and overwhelmed the victims. The Asian H5N1 bird flu affects the body the same way (60% chance of killing you). Luckily, it doesn’t spread from person to person (at least not yet).

The 2009 pandemic was a new Influenza A variant called “swine-origin H1N1”. The total cases and deaths weren’t too bad, but the types of patients were a bit frightening. “Normal” influenza endangers primarily the elderly and chronically ill, but 80% of the 2009 pandemic deaths were under 65, and 30% were previously healthy.

Because of pandemic fears, the CDC watches closely for new influenza viruses. There are always a few, but this year the number is low. No reason to worry about a pandemic right now, but keep your eye on evolving strains of influenza around the world. A Spanish Flu like pandemic could completely overwhelm the world’s healthcare system, and kill more people than most natural disasters combined!

Graveyard, Lawrence Massachusetts where more than 2000 people died from the Spanish Flu. Photo by Patti Gravel.

Graveyard, Lawrence Massachusetts where more than 2000 people died from the Spanish Flu. Photo by Patti Gravel.

2012-2013 Flu Season

Is this year worse than others? It’s definitely worse than last year’s mild season. CDC currently thinks this year is moderately severe, similar to 2007-2008.  Flu season severity largely depends on the most common influenza virus of the year. This year, a nasty called Influenza A (H3N2) accounts for about ¾ of the cases. Whenever H3N2 predominates, there tend to be more cases, symptoms, hospitalizations, and deaths.

Spreading Infection (Influenza and Other Respiratory Viruses)

When an infected person coughs, sneezes, or just breathes, they launch infected droplets into the air. People within 3 feet can breathe them in and get infected. Cover your mouth and nose with a tissue!

Most infected droplets fall on surfaces, and then get on the hands of the next person touching the surface. When contaminated hands touch face or mouth, you get infected. Wash hands, wash hands, wash hands!

Contaminated hands can spread virus to another hand (no polite hand shaking during flu season), another surface, or to food. Wash hands, wash hands, wash hands!

Incubation from influenza exposure to symptoms averages 2 days, but you start spreading the virus 24 hours before and 5-10 days after symptoms start. Young children can spread it several days before and up to 10 days afterwards (explaining pre-school and day care outbreaks!). Wash hands, wash hands, wash hands. (Do you get the theme here?)

Stay home if you are sick. Being macho and showing up at work (or school) usually just guarantees that more peers get sick.    

Flu Shots (More Appropriately Called Influenza Vaccination)

There is a lot of confusing press about flu shots- do they work or not? In addition, every time someone gets “the flu” despite vaccination, they complain about vaccine failure. Often, their illness just wasn’t influenza. So what’s the truth about influenza vaccines?

1)      Overall effectiveness of influenza vaccine is about 60%, averaged over years.

Vaccine Research. Photo from Novartis AG.

Vaccine Research. Photo from Novartis AG.

2)      The vaccine only targets 3 of the most common influenza viruses. It doesn’t prevent other influenza viruses, and it definitely doesn’t decrease other ILI.

3)       The CDC chooses the 3 influenza viruses almost a year in advance. Some years, estimates are very good (like this year) and the vaccine works well. Other years, the most common viruses aren’t covered by the vaccine.

4)      The vaccine generates the best immune response in young healthy people, but doesn’t work as well in the very young, the elderly, or the chronically ill – the groups that need it most.

5)      The vaccine works better if you had vaccine the year before – boosting your immunity instead of starting from scratch.

6)      Influenza vaccine is extremely safe, although it hurts and makes your arm sore for up to 2 days.

7)      Mild flu-like symptoms can occur after vaccination in children and teens with no previous vaccine exposure.

8)      Mild flu-like symptoms in adults are often blamed on the vaccine, but usually happen because IFI are darn common. The vaccine also takes 2 weeks for full effectiveness. If exposed within 2 weeks of the shot, you might still get sick.

Influenza Vaccine. Photo by El Alvi.

Influenza Vaccine. Photo by El Alvi.

My Vaccine Recommendations

Children under 4, pregnant women, adults over 50, and anyone with chronic illness should definitely get the vaccine every year, as soon as it is available. These groups risk serious complications and death from influenza, and statistics clearly show vaccine benefit, even if not as great as we could hope for.

For others, it simply makes sense to get the vaccine. It decreases your chance of feeling miserable for a week, missing work or school, and infecting others, including your family.  I think of flu vaccine like the lottery. Would you buy a ticket if you had a 60% chance of winning, and the cost was minimal?  If you didn’t win with those odds, would you give up on lotteries forever? Just get the shot!

Stay safe,

Sheila Sund, M.D.