USMLE notebook

Before I describe the different components involved in a vaccine, I want to address the so-called “bias” when it comes to the vaccine debate. The thing is, there is no “bias” from the medical side. There are facts that are back up by multiple studies, and then there are opinions that are based on fraudulent research done by a physician who has since lost his license.

And then there’s Jenny McCarthy, but we aren’t here to discuss people who offer their opinion on science when they probably don’t even know the difference between a virus and a bacteria.

So what is in a vaccine?

It really depends on the type of vaccine you’re talking about. The antigenic component varies based on whatever disease you’re trying to prevent. I’ll go into that further in a second, but I first want to focus on the “scary stuff” most people are worried about.

Thimerosal

Thimerosal is a preservative used to prevent bacterial and fungal growth. You know, critters that if injected into your child that would probably cause septicemia.  People get freaked out about thimerosal because it contains mercury. The funny thing is, thimerosal is only used in the flu vaccine. It has never been used in the MMR vaccine. It has also never been linked to any toxicity based on multiple studies.

Formaldehyde

Formaldehyde is used to inactivate viruses and detoxify bacterial toxins (like those in the tetanus vaccine.) A purification process is used to remove almost all formaldehyde in vaccines, although a very small amount will still remain. The amount of formaldehyde in vaccines is less than 200 parts per million (.02%) and several hundred times lower than the amount known to harm humans, even infants.  

Antibiotics

Sometimes very small amounts of antibiotic are added to a vaccine (ex. neomycin MMR) to prevent any bacterial growth in the vaccine. If a person is allergic to neomycin, they may end up having an allergic reaction. This is actually a significant (albeit rare) effect that needs to be monitored for.

Adjuvants

Adjuvants are added to vaccines to help increase the immune response to the antigen. None are known to be harmful.

I think the FDA has a really good page that answers most of your concerns as well: https://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/ucm187810.htm

And lastly, there are the antigens of whatever disease you’re trying to prevent. So if you’re trying to prevent the flu, the vaccine will contain a killed influenza virus.

I want to end this long post by talking about a few diseases your son would be vaccinated against if you choose to vaccinate. I want you to make an informed decision on your own rather by ridiculing anyone for their misguided opinions on vaccine safety. Vaccines are, quite literally, the most significant medical advancement in all of human history, and I will show this by talking about the various diseases they prevent. I’m not going to discuss all of them because as I started doing this I realized it was going to take a long time to discuss every disease (and I have boards to study for), but I’ll try to highlight the important ones.

Hepatitis B

Hepatitis B, while usually not as big of a concern if you get it as an adult, is extremely detrimental to children. Adults usually clear the illness without any lasting effects. However, children (90% to be specific) are unable to clear the infection and ultimately develop chronic hepatitis. Chronic hepatitis leads to liver cirrhosis, cancer, and death. About 2000 people die a year due to hepatitis B related liver disease in the United States.  This has been in steep decline since we began vaccinating for hepatitis B, as seen from this graph.

MMR

This is the biggie that everyone thinks causes autism even though there is literally no link shown between vaccines and autism. You can google this and find thousands of articles showing no link while there are maybe three that show there is some sort of link. But that’s the thing about research. Just because research says something does NOT mean it is true. Not all research is good research. Some research uses small sample sizes (cough cough Wakefield.) Or the research has a bias and a desired result. There are many things that contribute to what constitutes “bad research” which is why I think everyone should be required to take an epidemiology course at some point in their life, but I digress. Let’s talk about measles and rubella specifically.

Measles is a funny one to me because everyone thinks it’s “just a rash.” This shows the ignorance of many people who really know nothing about the disease they are speaking of. Measles causes 130,000 deaths around the world annually. Measles vaccination resulted in a 79% drop in measles deaths between 2000 and 2015 worldwide. However, as more and more people stop vaccinating, we start to lose herd immunity. Measles is a biggie for herd immunity because it is so incredibly contagious. For context, Ebola generally infects 2-3 people that have been in contact with a diseased individual. Measles infects 12-18 people who have been in contact with an infected individual. An outbreak of measles is extremely difficult to control.

Rubella does not generally cause as severe of disease in children. However, the problem with rubella is what it can do to a fetus. Congenital rubella syndrome (caused when a pregnant mother contracts the disease) can result in microcephaly, congenital cataracts, deafness, and heart defects. Since we have started vaccinating, the cases of congenital rubella have basically been eradicated from the US (see figure below.) CRS= Congenital Rubella Syndrome

I have included multiple links throughout this if you want to click to learn more, and I’ve provided more sources below: 

https://www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm

https://www.cdc.gov/hepatitis/statistics/

https://www.cdc.gov/vaccines/hcp/vis/vis-statements/hep-b.html

https://www.cdc.gov/vaccines/hcp/patient-ed/conversations/downloads/vacsafe-thimerosal-color-office.pdf