Cold and Flu

The Research on the Flu Vaccine

Every fall, advertisements appear reminding you to get your yearly flu shot. The Centre for Chronic Disease (CDC) recommends that everyone above the age of 6-months should get their vaccine by October. Despite the encouragement of healthcare providers to get the vaccination, a large part of the public is skeptical about the benefit of the vaccine, fearing side effects such as achiness or swelling at the site of the shot or the purported link between vaccines and autism. Is it really worth it to get the flu shot every year?

Let’s find out what the research has to say…


1. What is the Flu Virus?

The flu virus causes a highly contagious respiratory illness that can be caused by over 200 viruses. Symptoms typically present quickly and include sore throat, fever, cough, fatigue, headaches, muscle aches, and sometimes vomiting or diarrhea. Although the symptoms of a cold and the flu are similar and are both viral respiratory tract infections, there are some important differences.

The high fever associated with the flu, which can last for days, is not typically seen with a common cold. Additionally, the full body aches and weakened muscles are side effects the flu causes which set the two types of viruses apart. Moreover, the cold might make you miserable, but the flu will stop you dead in your tracks. The cold is viewed more as a major inconvenience than anything, but the flu can be deadly for certain populations. Approximately 80- to 90-percent of deaths attributed to the flu occur in those 65-years and older.


2. What is the Flu Vaccine?

Every year, the World Health Organization decides which strains of the virus (two of the type A and one of the type B strain) should be contained within the yearly flu shot. Although healthy people will usually recover from the flu without much issue, certain populations (such as infants and the elderly) will not. Vaccinating healthy people helps reduce the spread to those more vulnerable.

The flu vaccines can take two forms: inactivated or live attenuated. Inactivated vaccines use a chemical agent to kill the virus and is delivered intramuscularly. Live attenuated vaccines involve growing the virus via a series of cell cultures; over time, viruses are unable to reproduce but can still stimulate the immune system to build up a response to the virus. These vaccines are delivered from an aerosol shot into the nostrils. In the case of a flu pandemic, a specific vaccine is created which contains the only strain that has caused the outbreak.

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3. The Research: Does it Help?

The 2014 Cochrane Review analyzed the combined results of 116 studies up until May 2013 to answer the question “does the influenza vaccine prevent the flu?” The studies reviewed included studies that compare the effect of receiving the flu vaccine to either a placebo or receiving no treatment at all for nearly 100,000 people including pregnant women.

The findings show that the ability of the inactivated flu vaccine is meager; 71 people would need to be vaccinated to prevent one case of the flu in healthy adults. The live vaccine, found in the aerosol strain, has a similar effectiveness—46 people would need to be vaccinated to prevent one case of flu-like illness. Currently, the research is not conclusive as to whether the inactivated flu vaccine given to pregnant women can help prevent flu-like illness. It does not appear to prevent the flu in newborns.

Flu Vaccine

4. The Research: Does it Hurt?

This study also examined whether the flu shot may be responsible serious adverse side effects, such as the development of disease or neonatal health. According to the study, the yearly inactivated flu shot was not associated with the development of multiple sclerosis, immune thrombocytopenic purpura, or optic neuritis. The H1N1 inactivated virus was also not associated with Guillain-Barré syndrome. In addition, neither the seasonal or 2009 pandemic flu shots were found to be related to neonatal death or abortion.

Whether or not the vaccine causes the flu was not investigated in this study, but rest assured, feeling poorly after receiving the shot does not mean you have the flu. In fact, the development of mild flu-like symptoms is a good thing. The inactivated virus can’t cause the flu, but it can cause symptoms because your body is building up antibodies, which come in handy when you come in contact with the real virus.

Flu Shot

5. The Bottom Line

Although the evidence is weak to support that benefit of the flu in healthy adults, this study did not look at how vaccinating healthy people can help protect those vulnerable to the flu, such as the elderly or infants. Given that the flu shot is not associated with severe adverse outcomes, it might still make sense for healthy adults to the shot to help protect others. While this study did not look at the link between the flu shot and autism, many other studies have and have found that vaccines do not lead to the development of autism.

Whether or not you decide to get the flu shot, common sense hygiene is your best bet. This means limiting contact with those that are ill, covering your nose and mouth with a Kleenex when you sneeze (or sneezing into your arm instead of into space, handing washing frequently, disinfecting surfaces, and avoiding touching your eyes or mouth.

Cough, Sneeze


Catherine Roberts

Catherine is our go-to writer for women’s health news, diet trends and more. She’s dedicated to providing Activebeat readers with the information they need to maintain a healthy lifestyle every day.