Do you really need a flu shot? And other vaccine questions answered


Getting the annual influenza vaccination is one of the best ways to prevent the flu (in addition to handwashing and covering your coughs and sneezes).


Vaccination has been proven to save lives.


Confusion about the flu vaccine is common, though, and clear answers aren’t always easy to find. Let’s address some of those questions:


Do I really need the flu vaccine if I’m relatively healthy with few or no underlying conditions? What’s the worst that could happen if I contract the flu?


Young children, adults 65 and older, and people with certain chronic health conditions, including asthma, heart disease and diabetes, are most at risk for severe complications. It’s true that if you’re young and healthy, your risk for severe complications from the flu is lower.


However, if you contract the flu, you could potentially pass the virus along to someone in one of those other, vulnerable populations. The flu shot helps protect them as well as you.


Besides, even healthy individuals can experience fever, chills, nausea, vomiting, body aches and headaches associated with influenza infection. It’s a virus worth avoiding.


Can the flu shot give me the flu? It seems like I always get the flu when I get the shot. Does it even work?


No, the influenza vaccine won’t give you the flu. When you get this vaccination, you’re receiving either a version of the flu virus that isn’t active or able to infect you, or a single gene from a flu virus, which will just trigger an immune response.


Some people can have mild reactions to the vaccine that can include low-grade fever, headache and muscle aches, which could last for a couple of days.


The vaccine takes about two weeks to reach its full potential helping your immune system create flu antibodies. If, in the interim, you’re exposed to the actual flu virus, you might still contract the flu.


Is the flu worse than the potential side effects of the vaccine?


No vaccine is 100% effective, but the flu shot’s potential protection is so valuable that its benefits far outweigh its risks of side effects.


If you come down with the flu, symptoms could last up to two weeks, with a chance of associated cough lasting several weeks thereafter. That’s not to mention the lost time with family and friends and/or being away from work or school while you’re sick.


If you’re concerned about a previous vaccine side effect or an allergy to a vaccine ingredient, such as eggs, talk with your doctor or other care provider about an alternative vaccine that would be safest for you and your individual health needs.


Is it risky to get a flu shot while pregnant?


Pregnant women are encouraged to get the flu shot. According to the American College of Gynecology, getting the flu vaccine during pregnancy is safe and helps provide flu antibodies for both the mother and the baby. Newborn babies especially need that extra protection that their mother’s flu shot offers, since flu shots aren’t recommended for them until they’re at least 6 months old.


I saw that the flu shot has mercury and formaldehyde in it. How is that safe?


There’s a type of mercury used in some flu shots (the multi-dose versions) that prevents contamination from germs, bacteria and/or fungi. It’s different from the type of mercury that causes mercury poisoning, according to the CDC.


“Thimerosal [the ingredient in some flu shots] has a different form of mercury (ethylmercury) than the kind that causes poisoning (methylmercury),” the CDC website explains. “It’s safe to use ethylmercury in vaccines because it’s processed differently in the body and it’s less likely to build up in the body—and because it’s used in tiny amounts. Even so, most vaccines don’t have any thimerosal in them.”


As for formaldehyde, it’s diluted during the vaccine manufacturing process, the CDC says, but “residual quantities of formaldehyde may be found in some current vaccines.”


The amount of formaldehyde present in those vaccines is so small, however, that it doesn’t pose a safety concern—it’s an amount much smaller than the formaldehyde that already occurs naturally in the body, the CDC says.


Could vitamin C, vitamin D, elderberry and/or other “immune-boosters” work just as well as a vaccine to prevent the flu?


Currently, there’s no evidence that any of these substances prevent the flu virus. There is some weak evidence to suggest that vitamin C and elderberry may help reduce the severity and duration of the common cold and flu symptoms, but the flu vaccine is still the best defense against contracting the flu.


Does the flu shot contain cells from aborted fetuses?


Vaccines don’t contain any significant amount of human fetal tissue.


Some vaccinations, such as the MMR (measles, mumps and rubella) vaccine, historically were cultured from the cell line WI-38 human diploid lung fibroblasts. The manufacturer of the MMR vaccine, Merck, did report that this cell line was originally cultured more than 50 years ago from fetuses that were legally, electively aborted. No new tissue has been used to produce current vaccines. The cell line was replicated over multiple generations, and those cells were used in the culture for growing live viruses to produce vaccinations.


Using a human cell line is necessary because vaccines for humans don’t grow well in animal cells, according to manufacturers.


Does the flu shot contain pork byproducts?


According to the CDC, gelatin is used as a stabilizer in vaccinations. Stabilizers help the vaccine remain effective after the manufacturing process is complete.


Pork-derived gelatin (porcine gelatin) may be found in some vaccines, and it can also be found in many common household foods and medicines, such as Jell-O, acetaminophen, certain antibiotics, and cough syrups. This year, none of the flu vaccines provided by the Ohio State Wexner Medical Center contain any pork byproducts.



Sophia Tolliver is a primary care physician at The Ohio State University Wexner Medical Center and an assistant professor at The Ohio State University College of Medicine.


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