Ask Dr. Pat · Health

Influenza 2016: Do I Really Need to Get a Flu Shot?

Patricia Yarberry Allen, M.D. is a Gynecologist, Director of the New York Menopause Center, Clinical Assistant Professor of Obstetrics and Gynecology at Weill Cornell Medical College, and Assistant Attending Obstetrician and Gynecologist at New York-Presbyterian Hospital. She is a board certified fellow of the American College of Obstetrics and Gynecology. Dr. Allen is also a member of the Faculty Advisory Board and the Women’s Health Director of The Weill Cornell Community Clinic (WCCC). Dr. Allen was the recipient of the 2014 American Medical Women’s Association Presidential Award.

The influenza pandemic of 1918-1919 killed more people than World War I, estimated between 30 million and 50 million people. It has been cited as the most devastating epidemic in recorded world history. Known as the “Spanish Flu,” the influenza of 1918-1919 was a global disaster.  More people died of influenza in a single year than in four years of the ”Black Death” from bubonic plague from 1317-1351.

It is my responsibility as a primary care physician to recommend that my patients be up to date on all of their vaccinations. Each fall I have many conversations about the influenza vaccine. I am often told by patients when I recommend that they receive their influenza vaccine in September or October each year that they “never get the flu ” or that “I had it last year so I am protected” or “the people making this vaccine don’t know what kind of viruses will show up this year anyway so I don’t see any reason to have the vaccination.” This is information that I share with patients about influenza and how to prevent it.

What is influenza?  

The flu is a contagious, acute respiratory illness caused by influenza viruses that infect the nose, throat and lungs. It can cause mild to severe illness, and at times can lead to death.

What causes influenza?

In 1933, researchers discovered that viruses cause influenza in humans and isolated the human influenza virus. (Smith, W., C.H. Andrewes, and P.P. Laidlaw. 1933. Lancet. 222:66–68) Viruses are much smaller than bacteria. All they have is a protein coat and a core of genetic material, either RNA or DNA. Unlike bacteria, viruses can’t survive without a host organism. Viruses can only reproduce by attaching themselves to cells.  In most cases, they reprogram these cells to make new viruses until the cells burst, releasing millions of new viruses and the host cell dies.

Seasonal flu is caused by influenza virus types A and B primarily. Influenza A and B viruses are genetically similar enough to be included in the same family of viruses, the Orthomyxoviridae family. However, their genetic differences are significant enough to warrant separating the viruses into two different types, A and B. Influenza A viruses are further categorized by subtype and strain. Influenza B viruses are categorized only by strain. This difference is due to the more rapid mutation rate seen in influenza A viruses compared to influenza B viruses. Influenza A viruses are by far the most important human influenza pathogens but are also found in many different animals, including ducks, chickens, pigs and horses. However, the Centers for Disease Control and Prevention (CDC) states that wild birds are the natural hosts for all influenza type A viruses. Influenza B viruses circulate widely only among humans.

What are the symptoms of the flu?

The flu is different from a cold. Uncomplicated influenza usually comes on suddenly and is characterized by the abrupt onset of constitutional and respiratory signs and such symptoms as:

Muscle aches.
Nonproductive cough.
Sore throat.
Rhinitis (runny or stuffy nose).
Significant fatigue often lasting at least two weeks.

What are the serious complications of influenza?

Most people who get influenza will recover in several days to less than two weeks, but some people will develop complications as a result of the flu. A wide range of complications can be caused by influenza virus infection of the upper respiratory tract (nasal passages, throat) and lower respiratory tract (lungs). Sinus and ear infections are examples of moderate complications from flu, while pneumonia is a serious flu complication that can result from either influenza virus infection alone or from co-infection of flu virus and bacteria. Other possible serious complications triggered by flu can include inflammation of the heart (myocarditis), brain (encephalitis) or muscle (myositis, rhabdomyolysis) tissues, and multiorgan failure (for example, respiratory and kidney failure). Flu virus infection of the respiratory tract can trigger an extreme inflammatory response in the body and can lead to sepsis, the body’s life-threatening response to infection. Flu also can make chronic medical problems worse. For example, people with asthma may experience asthma attacks while they have the flu, and people with chronic heart disease may experience a worsening of this condition triggered by flu.Seasonal influenza is associated with large numbers of hospitalizations. The results of several studies demonstrate the substantial health impact of seasonal influenza and underscore the need to ensure vaccination of people at increased risk of serious influenza complications, especially people 65 years and older.The CDC estimates that from the 1976-1977 season to the 2006-2007 flu season, flu-associated deaths ranged from a low of about 3,000 to a high of about 49,000 people.

(“Influenza-Associated Hospitalizations in the United States 1979 Through the 2000-2001 Respiratory Seasons,” Journal of American Medical Association’s September 14, 2004 issue (volume 292, no. 11).

Thompson MG et al. Updated Estimates of Mortality Associated with Seasonal Influenza through the 2006-2007 Influenza Season. MMWR 2010; 59(33): 1057-1062.

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  • Dr. Pat October 31, 2016 at 2:59 pm

    Dear Holly,
    How kind of you to read and comment. I hope this information helps the readers to understand more about the reasons for influenza vaccination and encourage them to have their annual vaccination.
    Dr. Pat

  • Holly Day October 31, 2016 at 10:10 am

    Thank you, once again, Dr. Allen for this interesting history and good advice.