Student guest post: Seasonal Flu Vaccine: Why we need it

It's time for this year's second installment of student guest posts for my class on infectious causes of chronic disease. Fifth one this year is by Nai-Chung Chang. 

Of the many health problems that everyone is bound to have at some point, influenza, or just “the flu,” is one of the most prominent. In fact, we call the time during which it is most prevalent the “flu season”. It has now become a regular occurrence in the U.S. to just get a shot before the flu season hits, and be free of it for the rest of the year. In some cases, like me, people just decide not to get the vaccine at all. I say to myself all the time: “It is just the flu. If I do get it, I’ll just take a nap, and I’ll be fine.” However, there are serious complications with influenza if the individual is afflicted with certain diseases, making the vaccine a necessity. Even in the general population, influenza infections could lead to serious health problems, at a lower rate, that could complicate the daily lives of individuals.

Influenza is a generic description of a variety of strains of influenza viruses, including influenza A (H1N1, H3N2), and influenza B. It is a widespread virus, and can infect both human and animals, albeit with different strains. (1) The influenza virus is difficult to completely control since it constantly undergoes different changes through antigenic drifts and shifts, small and abrupt changes in the virus constructs, respectively. (2) It causes fever, coughs, sore throat, runny nose, and a host of other symptoms that target different parts of the body. In extreme, severe cases, it may cause the death of the infected individuals. It can spread from person to person up to 6 feet away through coughing and sneezing, spraying droplets containing infectious particles into the air. The droplets either lands in the other individual’s mouth, or is inhaled into the lung. Influenza is very contagious, due to the fact that it can infect others prior to the development of symptoms, as well as a period after. In addition, there exist asymptomatic carriers that can infect others without knowing. There are vaccines provided every year prior to the start of the “flu season:” a period of time in which the population is most likely to acquire the disease. Once the symptoms develop, it can be treated with antiviral medicine, such as Tamiflu (oseltamivir) and Relenza (zanamivir).

In addition to the problems that a regular influenza infection can cause, in individuals with certain diseases, complications could develop from the interaction between the influenza virus and the disease currently affecting the patient. In asthma patients, the attacks are often triggered by respiratory virus infection, whether by the virus particle itself or the inflammation resulting from the influenza symptoms. Also, the influenza viruses could augment natural responses to allergenic particles resulting in a more severe than normal attack; influenza patients with asthma are often hospitalized as the result. (3) In patients with cardiovascular disease, influenza infections represent a high level risk. The infection could destabilize existing plaques (blocks in the artery) in atherosclerotic patients. In addition to the acute responses from the destabilization, influenza infections could also induce chronic inflammation in the body, as well as reduced clotting ability. (4) For patients with diabetes, infection with influenza represents a high risk of hospitalization and death. In diabetics, the immune system is weakened, making it difficult to fight of the disease. In addition, the infection can cause fluctuation in the level of blood sugar in the patients, through natural immune responses, or lack of desire to eat due to the effects of the influenza symptoms. There is also an increased risk of acquiring pneumonia as a complication of the infection. (5) As in the case with diabetics, patients with cancer and HIV/AIDS are also likely to have complications due to weakened immune systems from both treatment and disease.

From the variety of complications that could result from influenza infections, one can now see that it is extremely important for an individual to receive the vaccines when available. In some places, vaccines are often offered free of charge, especially in workplaces that have high exposure risks, such as hospitals and research facilities. In addition to reducing the likelihood of being affected by influenza, flu vaccines have shown to have reduced the development and progression of other diseases such as chronic obstructive pulmonary disease (COPD). (6) For individuals with HIV/AIDS, vaccines are especially important since they are more vulnerable to infections. In addition, they must be aware of the type of vaccines they are using, since certain vaccines do not work sufficiently in people with immune-deficient issues. However, there exist other treatments for the prevention of the disease, such as chemoprophylaxis, that would allow these individuals to be properly protected against possibilities of infection. (7) With the prevalence of the influenza virus in both the U.S. and globally, it is important that an individual keep up with the most current vaccines, as they are designed to combat the most common forms that would appear that flu season, since the strains changes every year.

References:

1. CDC. Seasonal Influenza (Flu). http://www.cdc.gov/flu/index.htm
2. CDC. How the Flu Virus Can Change. http://www.cdc.gov/flu/about/viruses/change.htm
3. Glezen, W. Paul. Asthma, influenza, and vaccination. Journal of Allergy and Clinical Immunology 188(6): 1199-1206.
4. Madjid M, Nagahvi M, Litovsky S, Casscells SW, Influenza and Cardiovascular Disease. Circulation 108:2730-2736.
5. CDC. Flu and People with Diabetes. http://www.cdc.gov/flu/diabetes/index.htm
6. Poole PJ, Chacko E, Wood-Baker RWB, Cates CJ. Influenza vaccine for patients with chronic obstructive pulmonary disease. Cochrane Database of Systematic Reviews.
7. CDC. HIV/AIDS and the Flu. http://www.cdc.gov/flu/protect/hiv-flu.htm