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Influenza Vaccine: Risks vs Benefits

Influenza

Influenza, or the Flu, is caused by the Influenza Virus. The symptoms vary in severity, however, the most common include high fever, runny nose, sore throat, muscle pains, headache, coughing, and feeling tired. The flu season varies by geographic location and climate. Cold temperature and low humidity facilitate transmission and therefore, the flu season generally occurs in winter. In the United States, seasonal influenza is a cause of substantial illness, hospitalizations, and deaths every year.

Who is at higher risk?  

Adults aged 65 years old and older, healthy children especially those less than 2 years old, pregnant women in their second or third trimester, and persons of any age who have chronic medical conditions like asthma, diabetes, and obesity at higher risk for serious illness and death.

Since the 2010–2011 influenza season, ACIP and CDC have recommended that all persons 6 months old and older, unless medically contraindicated, should receive annual vaccination with the most up to date influenza strains. Before 2010, only persons 50  years old and older, pregnant women, persons aged 18 – 49 years with medical conditions that place them at high risk for influenza complications, health – care personnel (HCP), and children aged 6 months – 17 years were recommended for annual vaccination.

Drawbacks of the Flu Vaccine

Vaccination against influenza is not by any means perfect. Generally a single strain of influenza virus is the predominant cause of cases during an epidemic, however, in some years more than one potentially dangerous strain has been identified. Influenza virus frequently changes its antigenicity referred to as antigenic variation. By changing the antigen structure, a new virus with little or no antibody resistance can be formed and released on the population. This is why it is still possible to get influenza even after receiving a flu shot. Vaccines must be made and ready before the flu season arrives and therefore, it requires research and predictive as well as preventative strategies to prevent illness and death. Occasionally, the end of the influenza epidemic season is characterized by a newly developed strain. This can sometimes help predict the predominant strain the next flu season. Unfortunately, there are too many strains of influenza to cover in a single vaccine and not every strain of the virus can be effectively covered. For this reason, vaccination varies in effectiveness each season.

Another drawback to the vaccine is the decreased effectivity in protecting adults older than 65 years of age, a population considered to be at higher risk for influenza complications. This may reflect a response to the circulating influenza type seen mostly with influenza A virus. For the most part, adults over 65 years of age and those with chronic conditions still benefit from protection from a variety of influenza strains and have a tendency to get vaccinated.

Side Effects of the Flu Vaccine

The vaccine is generally well tolerated mild soreness is the most common complaint more commonly in women than men. Systemic reactions, malaise, flu-like symptoms, and fever are uncommon. Rates of transient fever were only slightly above the placebo recipients and allergic reactions can occur especially in individuals who are allergic to hen egg-containing products. There is also an association with a small increased risk of Guillain-Barré syndrome (GBS), however, the incidence of GBS might vary seasonally either because of circulating respiratory viral infections or owing to factors such as temperature, which can affect the distribution of illnesses that could be risk factors for GBS.

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Benefits of Getting Vaccinated

What makes vaccination so important is prevention and controlling the spread of disease. Getting vaccinated provides an individual with added protection against infection yet at the same it greatly reduces the risk of that same individual from infecting someone else. As mentioned earlier there are several strains of influenza and due to the lack of coverage, it is still possible to get the flu after vaccination. Reported Vaccine Effectiveness against influenza hospitalization ranges widely with some reporting numbers from 28-86%. The most significant factor, however, was the higher effectiveness (89%) against severe cases of influenza. Most patients who previously were infected by influenza and those over 50 years of age and those with chronic conditions were more likely to get the flu shot.

Myths and Beliefs about the Flu Vaccine

U.S. Navy photo by Mass Communication Specialist 2nd Class Laurie Dexter/Released
  • A common belief among health care providers is that they were not likely to experience a severe course of influenza illness and/or that influenza was a “manageable” disease. This was especially true for individuals who believed themselves or their children to be in good health or have a “strong immune system.” For these individuals, seasonal influenza vaccination was either “not necessary” or “optional.” The reality is, not all strains of influenza have the same effects on us and in certain situations antibodies from a previous infection help the body eliminate the virus sooner. This also does not take into consideration the patients that healthcare providers with this belief come in contact with.
  • Younger and self-reported “healthy” people were less likely to see a need for seasonal flu vaccination. The severity of influenza symptoms varies with each strain, however, many associate the common cold with the flu. Influenza symptoms are much more severe lasting approximately one week with 3 to 4 days of bed disability and missing 1 to 2 days of school or work. The symptoms are very severe and anyone can be affected no matter how healthy they are.
  • There is a belief that doctors recommended unnecessary vaccinations such as influenza as a way to make a profit. This is simply not true. Every year thousands of people die from complications caused by influenza. The goal is simply to prevent as much disease as possible and afterward, treat what could not be prevented. Also, the cost of treating a hospitalized flu patient is huge when compared to the cost of a vaccine.
  • Many believe the flu is an illness of manageable duration and tolerable symptoms. In non-severe cases, it is associated with 5 to 6 days of restricted activity and 3 to 4 days of bed disability, however, severe cases require hospitalization.
  • Some do not believe the vaccine would protect them from influenza. Unfortunately, as mentioned earlier the vaccine can not protect us from every single strain of the influenza virus but it does provide protection against the more severe and more common strains. As mentioned above, the virus can change itself and even create completely new strains to which there is no immunity.
  • It is common to hear people say “the flu shot gives you the flu.” This is not the case. The vaccine can produce mild side-effects but these symptoms are more closely related to common cold symptoms than those caused by influenza. The most common complaint is soreness at the site of injection.

Whether to get vaccinated or not, is ultimately your decision. I hope that by reading this, more people will understand that the vaccine is not perfect but it is an excellent method of protecting oneself and those who we come in contact with.

 

 

References:

  1. Magalhaes, I., Eriksson, M., Linde, C., Muhammad, R., Rane, L., Ambati, A., . . . Maeurer, M. (2014). Difference in immune response in vaccinated and unvaccinated swedish individuals after the 2009 influenza pandemic. BMC Infectious Diseases, 14, 319. doi:http://dx.doi.org/10.1186/1471-2334-14-319
  2. Nowak, G. J., Sheedy, K., Bursey, K., Smith, T. M., & Basket, M. (2015). Promoting influenza vaccination: Insights from a qualitative meta-analysis of 14 years of influenza-related communications research by U.S. centers for disease control and prevention (CDC). Vaccine, 33(24), 2741-2756. doi:http://dx.doi.org/10.1016/j.vaccine.2015.04.064
  3. Nyhan, B., & Reifler, J. (2015). Does correcting myths about the flu vaccine work? an experimental evaluation of the effects of corrective information. Vaccine, 33(3), 459-464. doi:http://dx.doi.org/10.1016/j.vaccine.2014.11.017
  4. Darvishian, M., Bijlsma, M. J., Hak, E., & van den Heuvel, E.,R. (2014). Effectiveness of seasonal influenza vaccine in community-dwelling elderly people: A meta-analysis of test-negative design case-control studies. The Lancet Infectious Diseases, 14(12), 1228-39. doi:http://dx.doi.org/10.1016/S1473-3099(14)70960-0
  5. Turner, N., Pierse, N., Bissielo, A., Huang, Q. S., Baker, M. G., Widdowson, M., & Kelly, H. (2014). The effectiveness of seasonal trivalent inactivated influenza vaccine in preventing laboratory confirmed influenza hospitalisations in auckland, new zealand in 2012. Vaccine, 32(29), 3687-3693. doi:http://dx.doi.org/10.1016/j.vaccine.2014.04.013
  6. Vellozzi, C., Iqbal, S., Stewart, B., Tokars, J., & DeStefano, F. (2014). Cumulative risk of guillain-barré syndrome among vaccinated and unvaccinated populations during the 2009 H1N1 influenza pandemic. American Journal of Public Health, 104(4), 696-701.
  7. Salmon, D. A., Proschan, M., Forshee, R., Gargiullo, P., Bleser, W., Burwen, D. R., . . . Lurie, N. (2013). Association between guillain-barre syndrome and influenza A (H1N1) 2009 monovalent inactivated vaccines in the USA: A meta-analysis. The Lancet, 381(9876), 1461-8. doi:http://dx.doi.org/10.1016/S0140-6736(12)62189-8

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Juan Antonio Aguilar Garcia, M.D.

Having the knowledge to help people live healthier and longer lives is a privilege. Sharing that knowledge with the world is an obligation.