Flu vaccination: Arm yourself against the anti-vax arguement

The flu vaccine. Always a hot topic, especially in years when the vaccine has poor efficacy as it does this year. At times like this, the anti-vax community can gain leverage. So let's take a look at some of the top arguments used in the anti-vax movement and see if we can shed some light on the controversy.

The flu vaccine makes you sick.
People will often say that they got the flu because of the flu shot. This is actually not possible. The flu shot is made with an inactivated, DEAD form of the virus that cannot replicate and transmit. While there can be side effects from the shot that make you feel "sick," this is not the flu. Additionally, the flu vaccine stimulates your immune system, which actually strengthens your ability to fight infections and avoid getting "sick." It is important to note, though, that getting the flu vaccine does not mean you are immediately protected. It typically takes about two weeks to gain the full advantage from the vaccine. People who were already exposed to the virus before receiving the vaccine or who are exposed shortly after vaccination will not be protected.

Brian Snyder/Reuters/Landov

The flu vaccine contains mercury that will poison you.
Flu shots that come from a multi-dose vial do typically contain thimerosal, an ethylmercury-based preservative to prevent any bacteria or fungus from contaminating the vaccine. Flu shots that come in prefilled syringes and the nasal flu vaccine do NOT contain this preservative (with the exception of the Fluvirin prefilled syringes from Seqiris, which contain trace amounts of thimerosal). It is important to note the distinction between ethylmercury (found in thimerosal) and methylmercury. Methylmercury is the form of mercury found in foods, like seafood, that is associated with neurological complications. While in vitro studies (in cell culture systems and not in the body) have found little difference between the effects of methyl- and ethylmercury, the story is quite different in vivo (in actual living creatures). Ethylmercury is cleared from the bloodstream significantly more quickly than methylmercury, minimizing the exposure of the body to mercury. Ethylmercury is also compartmentalized by the body more successfully than methylmercury, further limiting exposure. Some may argue that based on the in vitro evidence, ethylmercury is unsafe, but the in vivo data and years of studies have shown that this is not the case. But, if you still want to avoid mercury all together, you can get a prefilled syringe version of the flu shot that contains no thimerosal.

The flu vaccine causes the virus to mutate, becoming more virulent.

This is a popular argument used in the anti-vax community. While that is always a theoretical possibility, there is currently no scientific evidence that this is happening. The influenza virus has an extremely rapid mutation rate, whether you put selective pressure on it or not, so it’s going to be mutating all the time regardless of what we as humans do. This is just the nature of the virus’s replication; the enzyme it uses to replicate its genome makes a lot of mistakes, and the virus is perfectly happy to continue on with those mistakes (aka mutations).

The idea that vaccines create more virulent viruses is typically based on the fact that the use of antibiotics can lead to more pathogenic bacteria, which has been observed. But the vaccine works very differently from an antibiotic. In the case of bacteria, they directly come in contact with and are affected by the antibiotic, which gives bacteria that can survive while in contact a direct advantage. In the case of the vaccine, since it is priming an individual’s immune system and not directly contacting the virus, there is no such direct advantage to the virus. Even if the influenza virus you encounter is different from the vaccine strain, your immune system will be primed and you will have a better chance of successfully clearing the virus. While it is theoretically possible that by vaccinating, you remove the predominant influenza strains, leaving an opening in the environment for a “resistant” strain to fill, most of the highly virulent and dangerous strains have emerged in parts of the world where vaccination rates are very low, so this doesn’t seem to be happening.

Vaccination causes super strains of the flu virus to emerge that are immune to our vaccines. 

Influenza virus. Carrington College

People often further argue that our lack of vaccine effectiveness in recent years comes from the emergence of “super” strains of the virus that are “immune” to our vaccines. But the research suggests otherwise. Vaccinemakers use a less-than-ideal system for choosing the vaccine strains that relies on a test using ferrets exposed to the virus. This can lead to incorrect selection and a poor vaccine. Also, improved diagnostic techniques make it more likely for us to capture influenza infection than ever before, so people who would have been diagnosed with some unknown viral disease (and therefore considered “protected”) in the past are now being properly diagnosed as influenza patients. And we are learning that our vaccine production system making the vaccine in eggs leads to its own set of mutations in the vaccine strain that often dampen protection in people. A lot of groups are working to improve the vaccine production pipeline and find alternative ways that don’t involve growing the vaccine in eggs, so that will likely be the way of the future in 5-10 years.

Vaccines cause autism.
This claim is not unique to the flu vaccine and has been spouted at the forefront of the anti-vax community ever since 1998, when Andrew Wakefield and colleagues published a study looking at 12 children that claimed there was a link between the measles-mumps-rubella vaccine and autism. What people in the anti-vax community typically fail to realize is that since that article was published, it has been retracted (the authors themselves admitted their conclusions were inaccurate), Wakefield and colleagues have been found guilty of ethical violations and fraud, and Wakefield has been removed from the UK medical registry. They hand-picked the patients for their study and falsified data to ensure that they would conclude there was a link between vaccines and autism. Additionally, they had received funding from lawyers who had been hired by parents to bring lawsuits against vaccine companies. Since the Wakefield study, many large-scale studies have been performed to see if their initial findings could be confirmed in spite of the ethical issues with the study, but no corroborating evidence has been found. The link between vaccination and autism is based on fabricated data and has no true scientific merit.


In spite of the potentially poor efficacy, healthcare providers will still push for vaccination. Any protection is better than none, especially if you are in contact with the populations at high-risk of dying from infection, i.e. the elderly, babies, and immuno-compromised individuals. The more people who are protected (even if the protection is sub-optimal), the less likely it is for the virus to come in contact with these highly susceptible individuals, and healthcare providers rely on this to keep patients safe. The bottom line is we may have a sub-optimal vaccine, but a lot of people are actively working on that, any protection is still better than none, and there is no evidence that getting the vaccine has any negative impacts on the pool of viruses we are exposed to. So please do not be discouraged, and use your new flu vaccine knowledge to help educate others!