MetroWest Daily News, Framingham, MA
  • Dr. Jeff Hersh: It's flu season, time for a vaccination

  • The close quarters of being huddled inside due to cold weather, as well as the seasonality of flu cycles, makes the winter months the most common time for flu outbreaks.

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  • The flu is an infection due to influenza virus. It is spread from an infected person to someone else via droplets from coughs, sneezes or even talking.
    It can also be spread when the infected person has droplets on their hands and touches something that is then touched by someone who infects themselves by touching their own mouth or nose.
    The influenza viruses rapidly mutate, minimizing the ability of people’s immune systems to fight them off. There are two major immunogens (the proteins that stimulate the immune system) on the surface of a flu virus, hemagglutinin and neuraminidase; this is what the "H" and "N" stand for in the description of a flu virus (for example the H1N1 pandemic that killed over half a million people in the U.S. in 1918, and which was also flu type in the 2009 ‘bird flu’ outbreak that caused so much concern).
    In order to "prime" the immune system, a yearly vaccination is developed which is aimed at the type of virus predicted to "go around." Since it takes nine months to manufacture a sufficient supply of vaccines, the predicted flu strains for the annual vaccine is based on worldwide monitoring and tracking by the Centers for Disease Control and Prevention and the World Health Organization. As you can imagine, this is not a precise science, and some years the "prediction" is a closer match to the actual viral strains that "go around" than other years.
    The closer the prediction to the actual viral strain, the better the efficacy of the vaccine to prevent disease. When the match is very good, vaccination can prevent 50 to 90 percent of people from developing infection (based on blood tests); when the match is poor the efficacy can go down to 30 percent or less.
    There are two major ways to make vaccine. One is by using inactivated strains of the "predicted" flu strains (the yearly vaccine is developed against the three major candidates for the year’s flu); this is the type that is given by injection, and is called TIV (trivalent inactivated vaccine).
    The other major vaccine production method relies on live virus that is manipulated so as not to be able to multiply (live attenuated influenza vaccine, LAIV); this is the type of vaccine that is squirted into the nose.
    Flu vaccine is recommended for everyone over 6 months of age unless they have a contraindication (discussed below). LAIV is approved for people 2 to 49 years old. TIV should be used in the other age groups, with intradermal (under the skin) vaccination a possibility in those 18 to 64.
    Flu vaccine is especially important in high-risk people, such as those over age 65, healthcare workers (to prevent them from spreading the flu to their patients), pregnant women and those at risk for complications if they get the flu (such as those with lung or heart disease or those who are immune-compromised).
    Page 2 of 2 - Kids six months to eight years old should get two doses separated by a month (unless they had two doses in a previous year, in which case one dose is sufficient). Everyone else typically requires only one dose.
    People with a history of a severe allergic reaction to flu vaccination or those who developed Guillain-Barre syndrome within 6 weeks of a previous flu vaccination should not receive vaccination. LAIV should not be given to anyone with a compromised immune system, lung disease (such as asthmatics or those with COPD), cardiovascular disease, diabetes, kidney insufficiency, pregnant women, kids less than 2 years old or close household contacts of these patients (TIV should be used instead).
    Eggs are used to prepare flu vaccines, however new research has shown that egg allergy is not a contraindication to flu vaccine; people with a history of egg allergy should receive the flu vaccine only after consultation with the physician, and under close observation (in case a vaccination allergic reaction occurs).
    Arm soreness in those getting an intramuscular vaccination, runny nose for those getting intranasal administration, and/or minor flu-like symptoms commonly occur after flu vaccination, but should not dissuade people from getting vaccinated.
    Research is being done to develop a universal flu vaccine that would be beneficial against all strains of flu. In the meantime, the flu vaccine based on the year’s predicted strains should be part of our annual routine to prevent illness.
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