There are a lot of misconceptions surrounding the science behind flu shots: it’s too late or too early to get one, they don’t work, or even worse, they’ll make you sick. Since flu season is upon us, let’s break down the when, why, and how of who should get a flu shot.
Will the Flu Shot Make You Sick?
The flu shot does not and cannot give you the flu. There are cases of mild, flu-like symptoms occurring as a side effect of the vaccine, but these cases are rare and the symptoms fall far short of the full blown flu. The reason the flu vaccine cannot give you the flu is that the virus contained within the vaccine is either entirely inactive or weakened to the point of ineffectiveness.
The misconception that the flu shot can actually give you the flu likely sticks around because the vaccine typically takes two weeks to start working. If you get the flu shot, but are then exposed to the flu in that two week period before your body has had a chance to full develop the necessary antibodies, you could come down with the flu and blame the shot.
Does the Flu Shot Work?
Another issue is that the flu vaccine is not close to 100% effective, as we have come to expect from other vaccines like those for measles or polio. The effectiveness of the flu vaccine instead hovers around 50% on average. Last year, the vaccine did a bit better, at 63% effectiveness, but two years ago, that fraction dropped to 23%.
This range is due to the fact that the flu virus constantly mutates and comes in many varieties or strains. Each year scientists take an educated guess at what strains will be most prevalent that year and thus which ones should go into the vaccine.
So the flu vaccine is not bulletproof. But if I handed you a card with a 50% chance of avoiding being laid up in bed for a week with the flu, wouldn’t you take it? A fifty-fifty shot is better than no protection at all.
The flu shot also works not just for the person getting it, but for anyone that person comes into contact with. The fewer people out there with the flu, the less flu there is overall, and the more all of us flu-shot receivers can protect those who are at higher risk for flu complications and/or those who were not able to get a flu shot.
The US Center for Disease Control reports that death rates due to the flu have varied between 3,000 to 49,000 per year over the past 30 years. The vast majority (80-90%) of those fatalities were people over the age of 65. Other groups that are at high risk for flu complications include children under four years of age, anyone with cardiovascular or breathing issues (like asthma), those with renal or metabolic disorders (including diabetes), anyone who is immunosuppressed including due to HIV treatment or pregnancy, residents of chronic care facilities like nursing homes, and American Indians or Alaskan natives. These are also the same groups, along with health care personnel, that receive priority in case of a flu vaccine shortage.
Who Should Get a Flu Shot, and When?
Doctors usually recommend getting your flu shot as early as they become available, typically by late September. Remember that you aren’t actually protected until about 2 weeks after the shot so in order to have a better chance of avoiding the flu, you need to get the vaccine before you are exposed. If your schedule is anything like mine, getting the vaccine early also assures that you actually get it, rather than putting it off until you eventually forget.
Doctors usually recommend getting your flu shot as early as they become available.
One exception to the early bird recommendation is for those in the 65 years and over age group. Older immune systems do not always maintain the protective effects of the vaccine for more than 3-4 months. So if you are over the age of 65, you may want to wait until November to get your flu shot.
However, flu season starts in October but can extend as late as May, and flu activity doesn’t peak until February or March. So as long as there is still flu around, it is not too late to get a flu shot.
The CDC recommends that everyone 6 months and older receive a flu shot every year with very rare exceptions. Pregnant women and those with chronic health conditions should still get a flu shot. If you are not feeling well at the time you would like to get your flu shot, talk to your doctor about a possible delay, although minor symptoms are usually not a problem.
The small group of people who should not get a flu shot are those with severe, life-threatening allergies to the vaccine or the ingredients used to make it (including gelatin and antibiotics). An egg allergy is no longer an impedance to getting a flu shot, nor are those with egg allergies required to stay for monitoring for 30 minutes following the vaccine. However, anyone with an egg allergy is still urged to get their flu shot under the supervision of a doctor.
There are a few different flu vaccines offered every year and recommended by the CDC. For example, people over 65 years of age are typically given a high dose shot while children under 18 years of age are not given an intradermal shot. Last year the nasal spray was recommended for children, and anyone else who is not a fan of needles, but it turned out to be < 5% effective. So for the 2016-2017 flu season, the CDC does not recommend that the nasal spray be used for vaccinations. For more information on the specifics of the flu vaccine each year, which ones are approved, see the CDC’s website.
Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.
Image courtesy of shutterstock
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