Saturday, June 1, 2019

Ten myths about vaccination

I was recently asked to put together a list of common vaccine myths for a university course that a friend teaches. Since this information is helpful for others, I thought I'd share it on my blog.

These are just a few of the myths that I've seen about vaccines and vaccination. I've chosen 10 myths that I commonly come across in sharing science on social media.

Vaccines are 100% safe and effective

This is something that people sometimes think about vaccines. However, vaccines do carry some risks. Most are mild and soreness at the injection site is the most common. The more serious risks, such as an allergic reaction to a vaccine ingredient, are rare and happen once in every million or so doses. Many people will look at these risks and conclude that vaccines are worse than the diseases vaccines protect against. However, the serious risks from these diseases are very common (ranging from one in ten to one in one thousand people infected) and are far more severe than the most severe complication from vaccines.

For more information on the risks of vaccines and vaccine preventable diseases, see this resource:`

I have a series of infographics on vaccine risks compared to the risks of vaccine-preventable diseases:

Vaccines cause autism
This is a common misconception that was started by a doctor who has since been stripped of his medical credentials due to the fraud he committed in trying to make the link. Many studies have been conducted since then with millions of kids with and without autism, including siblings, and no link between vaccination and autism has been seen. Some of this research was even funded by anti-vaccine groups without a link being seen. The reason why so many still believe this is because of the timing. A child will get the MMR vaccine and then a little bit later get diagnosed with autism. This type of correlation makes it seem like it is happening, but this type of association on its own isn’t reliable. About the time that kids are given the MMR vaccine is when signs of autism are first becoming noticed which is what leads to diagnosis. The association is just coincidental. What causes autism is unknown, but right now the research suggests that autism is a genetic condition. The repetition of the myth that vaccines cause autism is harmful to autistic people as it implies that it would be better to die of a disease, like the measles, rather than get autism.

For the findings of Andy Wakefield’s fraud, see this article in the BMJ:

A study funded by an anti-vaccine group that found no link between the MMR vaccine and autism:
A good article looking at vaccination, autism and temporal associations:
An article on genetics and autism:

Vaccines are corporate cash cows
There is a common idea that vaccines are pushed in order to make money off of people rather than to help the public. However, most vaccines cost healthcare providers more than they make giving vaccines. Additionally, vaccines only make up a small portion of the sales from drug companies and the profit margin is lower than other drugs. Vaccine preventable diseases tend to be much more expensive than vaccines. For example, hospitalization from the measles can cost tens of thousands of dollars. If this type of mindset were true, drug manufacturers and healthcare professionals would oppose vaccines as they would stand to make more off of vaccine preventable diseases than from vaccines. This myth simply isn’t true.

The costs of vaccines for healthcare professionals:

The costs of manufacturing vaccines:
The cost of containing one case of measles (from 2004):

Vaccine manufacturers can’t  be sued
Some people claim that vaccine manufacturers cannot be sued. However, lawsuits against vaccine manufacturers can and do happen. This myth just isn’t based in reality.

An article discussing a lawsuit against Merck over the shingles vaccine:

The diseases vaccines target are mild childhood diseases
This is a claim that is often used to try and negate the importance of vaccines. Part of the issue is that vaccines are so successful that people have forgotten how bad these diseases actually are. Measles kills one out of every 1000 people that are infected if medical care is available. Without medical care, the death rate is much higher with up to one in ten dying from the virus. Beyond causing death, many of these diseases also cause long-term harm such as blindness, deafness, paralysis, etc. Others cause more severe symptoms, including an increased risk of death, if someone gets the disease when they are older. Still others cause cancer that the vaccine would prevent.

The severity of vaccine preventable diseases in adults:

Some images of vaccine preventable diseases (warning some are graphic):
Some infographics I've made on vaccines and vaccine preventable diseases:

Vaccines cause viruses and bacteria to mutate
This myth is a bit trickier to address since there is some truth to the idea but it doesn’t apply the way people think of it. Viruses, bacteria and other microbes are constantly evolving and mutating to be successful (ie., replicate). Vaccines could theoretically cause viruses to mutate as these microbes are constantly evolving to avoid the immune system. However, this isn’t commonly seen with vaccines. Part of this has to do with what vaccines target. Often vaccines will target a portion of a protein that is exposed in either the virus or bacteria. With viruses, these exposed portions of the proteins are often required to interact will cells to gain entry. Because of this, mutations changing the part that enables cell entry, which vaccines can also target, could render a virus unable to enter a cell and be a dead end (the virus can't infect that host anymore). It wouldn’t matter that the vaccine cannot train the immune system to target it because the virus couldn’t enter the cells and cause disease. This type of evolutionary pressure is too difficult to overcome without changing how the virus interacts with its host. Also, with some bacterial vaccines the target isn’t the pathogen, but rather is a toxoid that the bacteria is making (such as the tetanus vaccine). That means there is no evolutionary pressure for the vaccine. Another consideration is that vaccines which cause mutation are not released as the risk of the vaccine is too high compared to the benefits from it.

Why drugs drive resistance but vaccines don’t:

Viral evolution:
The Red Queen hypothesis:

Toxoid vaccines are a type of subunit vaccine:

The flu vaccine gives people the flu
This is a common misconception about the flu vaccine. The injected flu vaccine cannot cause the flu because the influenza viruses in the vaccine have been chemically killed and are no longer able to infect cells. The vaccine can cause mild flu-like symptoms, but this is just the immune system being triggered. There is a live flu vaccine, given as a nasal spray, but the strains have been weakened, or attenuated, to the point that the cannot cause disease but still cause an immune response. Another reason people might mistake the flu vaccine as the cause of illness is that it takes 2 weeks for the vaccine to be effective after it is given. If you get sick with the flu within that time frame it’s from another source and not the vaccine. People also mistake bad colds or other diseases for the flu. Colds make people feel bad but they are able to function. The flu can result in hospitalization and is a much more serious illness.

Misconceptions about the flu and flu vaccines:

Ten flu myths:
Why the flu vaccine can’t give you the flu:
The differences between the flu and colds:

All vaccines shed and can get people sick
This is a very common misconception that is based on not understanding what shedding is. Simply put, shedding is when a pathogen leaves a host to infect another host. Sneezing, coughing, etc. are ways that pathogens can be shed. With vaccines, only live vaccines have the potential to be shed, but unless the pathogen has the potential to undergo a process known as reversion (the weakened vaccine strain mutating to become full infectious again), what is shed is the vaccine strain. Only a few vaccines have been seen to undergo reversion to a fully infectious pathogen: the oral polio vaccine and the smallpox vaccine are two well documented examples of this. Researchers working on vaccines are very mindful of the danger of reversion and take steps to try and prevent it. This has been one of the limiting factors for developing vaccines for a variety of diseases, such as SARS coronavirus.

Viral shedding:

Computer modeling to develop better live-attenuated influenza vaccines:
Live-attenuated vaccines and reversion:
How SARS-CoV vaccine candidates undergo reversion:

The HPV vaccine is killing healthy kids
This is a myth that is based on taking the personal tragedies of families and twisting them for gain. The HPV vaccine doesn’t contain any live virus, but just parts of different HPV strains. The reason why this vaccine is so important is because these HPV strains cause a variety of cancers. The HPV vaccine has led to a reduction in cancer where it has been widely adopted. People think the HPV vaccine is killing kids due to a temporal association. The kids get the vaccine before they are sexually active, but then when something bad happens and the vaccine is blamed because it happened before the event. People try and make sense of tragedies, and often something is singled out as a blame. There are unscrupulous people who will prey on those that are grieving to use that story to make money. I'm not going to link to those sites, but they often sell people herbal supplements to "detox" from vaccines and/or replace vaccines.

HPV vaccine myths:

More information on the HPV vaccine:
The HPV vaccine and cancer prevention:
Australia is close to eliminating most HPV cancers due to the HPV vaccination program:

The flu vaccine isn’t necessary
This is a myth that doesn’t make sense to me, but is rooted in the gambler’s fallacy. Some people think that because something bad hasn’t happened to them for a number of years, then the risk of something bad happening is low. The seasonal flu kills hundreds of thousands of people each year. Pandemic strains of the flu kill many more people than that, especially healthy people as those strains trigger something called a cytokine storm where the immune system is over activated to the point of death. This is why the 1918 flu was so deadly to young people and killed so many. Another reason why some don’t think that the vaccine is worth getting is because of reports on vaccine effectiveness. With vaccines, effectiveness is a measure of how well a vaccine prevents initial infection. But this calculation does not account for other impacts that vaccines can have which include reduction of symptoms severity and duration if the vaccine doesn’t prevent an initial infection. For someone who is in a high risk group, getting the flu vaccine is the difference between recovering at home and needing hospitalization with the risk of death.

Gambler’s fallacy:

Influenza viruses causing cytokine storms:
Why the 1918 influenza outbreak killed so many young people:
Vaccine effectiveness:
The flu vaccine reduces symptom severity:
The flu vaccine can reduce symptom severity even against strains not in the vaccine:
A recent estimation of the worldwide death rate due to influenza:

Additional reading:

Simply put, vaccines save lives:
Vaccines as a proactive approach to emerging infectious diseases:
20 questions about vaccines: