Should You Get a Flu Shot?

I know I’ve been absent from this blog for about a thousand years, but I’m back for a special flu season-themed edition. I got an assignment about social advocacy for English, and I decided to further the conversation about flu shots. Most people seem to be apathetic about flu shots, and I want to change that. To force the reader to make a decision on where they stand on this issue, I have tried to compile an overview of the arguments and research to help you make an informed choice about whether or not a flu shot is right for you and your family.

Disclaimer: I decided to do this blog post as an assignment for school. I have no ties to pharmacological companies, governimages-1ment organizations, or pro- or anti-vaccination causes. I just wanted to include this disclaimer to show that I don’t have an agenda and can be an unbiased spectator in this issue.


Last flu season’s vaccine effectiveness was approximately 40 percent [1]. Flu shot opponents argue that this is not enough, but proponents believe some protection is better than none.

Overall Effectiveness

The least effective vaccine was produced in 2004-05, with only 10 percent effectiveness. In contrast, the most effective vaccine, with 60 percent effectiveness, was produced in 2010-11 [1]. Why does the effectiveness vary so greatly? There are various types of influenza viruses that are constantly evolving. Months before the flu season begins, scientists have to make their predictions about which viruses will be most prevalent. If the prediction doesn’t match well with what viruses are actually most common that season, the vaccine is not very effective [2]. However, an artificial challenge study shows that when the influenza type matched the type in the vaccine, the protection rate was approximately 96 percent [4]. A meta-analysis of influenza vaccine studies shows that flu vaccines can provide some protection, with the elderly being the least protected and young children having the strongest protection [3].

imagesAn article from the Washington Post is more critical of flu vaccines, stating that even though vaccination rates among the elderly are increasing, the rates of infection for influenza and pneumonia aren’t decreasing [5]. Moreover, studies that analyze effectiveness based on antibody response are prone to overestimate effectiveness. Vaccines that are grown in eggs, as many are, contain inactivated viruses that can mutate while in the egg, greatly reducing their effectiveness [6]. Obviously, there are many factors that must be considered when discussing effectiveness of vaccines.

Effectiveness in Adults

Multiple studies show that flu vaccinations can reduce days of work lost, doctor visits, and illness in adults [7, 8].

Effectiveness in Children

Because it’s unethical to actually keep children or elderly people from being vaccinated, clinical trials to study effectiveness are not done on them [16]. Therefore, most of the information we have is based on observational studies. These studies aren’t very definitive and indicate varying degrees of effectiveness [17, 18, 19].

Effectiveness in Elderly

Two studies done on the elderly show that studies may be overestimating the effectiveness in preventing death due to selection bias [21] and that vaccination doesn’t reduce death in elderly men who are hospitalized because of influenza [22]. The elderly aren’t protected as effectively by the flu vaccine because they don’t produce as many antibodies, but a new flu shot with a greater amount of antigens is more effective in the elderly and can cause a greater immune response [20]. However, no studies have been done on the effectiveness of this type of vaccination yet.


When looking at the ingredients list of the flu shot, some may seem concerning. People cite possibly dangerous ingredients as a reason for avoiding the vaccination, but others are more worried about the effects of the flu. Flu vaccines commonly include ingredients such as thimerosal, formaldehyde, egg proteins, polysorbate 80, and sucrose [28, 31]. People allergic to any of the ingredients or those who developed Guillain-Barré syndrome (a rare syndrome that can occur after viral infections and flu immunizations [29]) after immunization might want to further discuss options with their doctors before getting a vaccine [30].


Thimerosal is a preservative that contains mercury, but it is only used in multi-dose vials nowadays, [31] which means you can still get vaccinated if you have concerns about its safety. With that being said, many opponents of the flu vaccine cite thimerosal as a reason to not get a flu shot. According to Natural News, flu vaccines contain mercury in quantities thousands of times greater than the legal limit in drinking water [32]. (It should be said that I couldn’t find a source to corroborate this claim and that this source isn’t the most trustworthy.) There are a few actual scientific studies that implicate mercury as a possible neurodevelopmental toxin [33, 34].

However, science also shows a different side of thimerosal. The Institute of Medicine’s committee found no link between thimerosal and autism, and there has not actually been a study that found thimerosal exposure from vaccines causes harm [35]. The type of mercury found in thimerosal is ethylmercury, which, according to the CDC, is eliminated quickly from the body [36]. Many studies have found that thimerosal is safe when used in vaccines [36].

Thimerosal in Infants

Some studies show that thimerosal in vaccines is even safe for infants. For example, methylmercury (mercury which is found in fish and isn’t expelled from the body as quickly) was used to see if high concentrations would be passed from a mother to a fetus [37]. The children did not suffer any harm as the result of exposure to methylmercury. Using the guidelines for methylmercury exposure, researchers measured peak possible amounts of exposure to thimerosal due to immunization in infants and still found the levels to be lower than the safe amounts of methylmercury [38].


Formaldehyde inactivates viruses and is only found in trace amounts in vaccines [25]. It is found in the air, common foods such as apples and carrots, and our body, which regularly metabolizes it [27]. A study done on rats found that formaldehyde damaged endothelial cells, [26] but, according to the FDA, even newborns can tolerate the amount of formaldehyde in a vaccine. A newborn has 50-70 times as much formaldehyde in its body as is in a single vaccine [25].

Egg Allergies

If you’ve avoided flu shots up until this point because you’ve had an egg allergy, you’re in luck. One type of vaccine – called recombinant – is produced without using eggs [23] and has been recommended by the CDC for those withegg allergies. However, it is only recommended for people ages 18 to 49 [24].

Untrustworthy Sources

download-1When searching for information about flu shot safety, you can’t trust every website you find. Many sites have hidden agendas: they jump on the “don’t vaccinate” bandwagon to promote their own stores, sell vitamins and supplements, and increase their popularity [15]. They often cite research that doesn’t actually support their claims. See references 9, 10, 11, 12, 13,  and 14 to see examples of sites such as these.

In Conclusion…

When considering flu shots, only one thing is for sure: more research needs to be done. It’s up to you, the reader, to educate yourself in matters of public health and make informed decisions. By now, I hope you have considered whether you will get a flu shot this season. Until next time, when I discuss another fascinating science topic.

Oh, and before I forget – there are other points of contention involving this topic, such as possible adverse events following vaccination or if the flu is as dangerous as it seems, but that’s just too much to fit in one blog post. If you’d be interested in a follow-up post, please comment below, and I’ll do it.



  1. Influenza (Flu). 2018 Nov 15 [accessed 2018 Dec 31].
  2. Influenza (Flu). 2018 Sep 4 [accessed 2018 Dec 31].
  3. Efficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis. 2011 Oct 25 [accessed 2018 Dec 31].
  4. Donikian MA, McKee J, Greene LC. Challenge versus natural infection as an index or protection after influenza immunization. [accessed 2018 Dec 31].
  5. A Shot of Fear. 2005 Oct 25 [accessed 2018 Dec 31].
  6. Cohen Sep J, Voosen Dec P, Gronewold N, Wadman Dec M, E&E NewsDec. Why flu vaccines so often fail. 2018 Dec 26 [accessed 2018 Dec 31].
  7. Bridges CB. Effectiveness and Cost-Benefit of Influenza Vaccination of Healthy Working Adults. 2000 Oct 4 [accessed 2018 Dec 31].
  8. The Effectiveness of Vaccination against Influenza in Healthy, Working Adults | NEJM. [accessed 2018 Dec 31].
  9. Why Not To Get the Flu Shot. 2017 Feb 26 [accessed 2018 Dec 31].
  10. 5 Research Based Reasons To Avoid The Flu Shot! 2018 Dec 7 [accessed 2018 Dec 31].
  11. 4 Reasons to Avoid Getting a Flu Shot. 2017 Oct 23 [accessed 2018 Dec 31].
  12. New Study Shows Vitamin D Cuts Flu by Nearly 50 Percent. [accessed 2018 Dec 31].
  13. Bartlett E. Should I Get A Flu Shot? 5 Reasons Why Not. [accessed 2019 Jan 1].
  14. BOMBSHELL: Flu shots scientifically proven to weaken immune response in subsequent years… researchers stunned. 2018 Sep 17 [accessed 2018 Dec 31].
  15. Lee BY. You Should Get Your Flu Shot And Ignore This Supplement Advice. 2018 Sep 30 [accessed 2018 Dec 31].
  16. Moyer MW. Flu Shots May Not Protect the Elderly or the Very Young. 2012 Oct 18 [accessed 2018 Dec 31].
  17. Kelly H, Jacoby P, Dixon GA, Carcione D, Williams S, Moore HC, Smith DW, Keil AD, Van P, Richmond PC, et al. Vaccine Effectiveness Against Laboratory-confirmed Influenza in Healthy Young Children: A Case-Control Study. 2011 Feb [accessed 2018 Dec 31].
  18. Joshi AY, Iyer VN, Hartz MF, Patel AM, Li JT. Effectiveness of trivalent inactivated influenza vaccine in influenza-related hospitalization in children: a case-control study. [accessed 2018 Dec 31].
  19. Jefferson T, Smith S, Demicheli V, Harnden A, Rivetti A, Di C. Assessment of the efficacy and effectiveness of influenza vaccines in healthy children: systematic review. [accessed 2018 Dec 31].
  20. Flu Shots: Facts and Fallacies. [accessed 2018 Dec 31].
  21. Baxter, Roger, Lee, Janelle, Bruce. Evidence of Bias in Studies of Influenza Vaccine Effectiveness in Elderly Patients. 2010 Jan 15 [accessed 2018 Dec 31].
  22. Joshi M, Chandra D, Mittadodla P, Bartter T. The Impact of Vaccination on Influenza-Related Respiratory Failure and Mortality in Hospitalized Elderly Patients Over the 2013-2014 Season. 2015 Feb 23 [accessed 2019 Jan 1].
  23. Influenza (Flu). 2018 Oct 4 [accessed 2018 Dec 31].
  24. Media Advisory. [accessed 2018 Dec 31].
  25. Center for Biologics Evaluation and Research. Vaccine Safety & Availability – Common Ingredients in U.S. Licensed Vaccines. [accessed 2018 Dec 31].
  26. Lin Z, Luo W, Li H, Zhang Y. The effect of endogenous formaldehyde on the rat aorta endothelial cells. 2005 Nov 15 [accessed 2018 Dec 31].
  27. Harpocrates Speaks. [accessed 2018 Dec 31].
  28. Vaccine Excipient & Media Summary. 2018 Jun [accessed 2019 Jan 1].
  29. Duda K. How Is Guillain-Barre Syndrome Treated? [accessed 2018 Dec 31].
  30. Duda K, Jelic S. Who Should Not Get Flu Shots. [accessed 2018 Dec 31].
  31. Vaccines & Immunizations. 2018 Jul 12 [accessed 2018 Dec 31].
  32. Flu vaccine contains 25,000 times more mercury than is legally allowed in drinking water. [accessed 2018 Dec 31].
  33. Geier DA, King PG, Geier MR. Mitochondrial dysfunction, impaired oxidative-reduction activity, degeneration, and death in human neuronal and fetal cells induced by low-level exposure to thimerosal and other metal compounds. 2009 Jun 11 [accessed 2019 Jan 1].
  34. Leong CC, Syed NI, Lorscheider FL. Retrograde degeneration of neurite membrane structural integrity of nerve growth cones following in vitro exposure to mercury. 2001 Mar 26 [accessed 2018 Dec 31].
  35. Center for Biologics Evaluation and Research. Questions about Vaccines – Thimerosal in Vaccines Questions and Answers. [accessed 2018 Dec 31].
  36. Thimerosal in Vaccines Thimerosal | Concerns | Vaccine Safety | CDC. [accessed 2018 Dec 31].
  37. Davidson PW. Effects of Prenatal and Postnatal Methylmercury Exposure From Fish Consumption on Neurodevelopment. 1998 Aug 26 [accessed 2018 Dec 31].
  38. Mitkus RJ, King DB, Walderhaug MO, Forshee RA. A Comparative Pharmacokinetic Estimate of Mercury in U.S. Infants Following Yearly Exposures to Inactivated Influenza Vaccines Containing Thimerosal. 2013 Oct 10 [accessed 2018 Dec 31].

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