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Vaccines show our bodies part of a germ called an antigen. Our bodies then naturally create a disease-fighting protein against that antigen called an antibody. Antibodies work to get rid of the germ’s antigen. Our immune cells then remember how to make more of those antibodies if we encounter that germ in the future.

Learn more here: Do You Know How Vaccines Work? Here’s a Simple Analogy. — Boost Oregon, Video link: how do vaccines work?

An effective vaccine safely exposes our bodies to an antigen that our immune system needs to recognize and protect us from. There are four main ways that we have learned how to do this:

1. Live-attenuated vaccines use a weakened version of the germ;
2. Inactivated vaccines use a dead germ;
3. Partial germ vaccines use a protein or sugar from the germ; and
4. mRNA vaccines use the genetic code for the antigen from the germ.

In each of the above processes, the antigen is strong enough to prompt a natural immune response from our bodies but weak enough to avoid any harm or illness from the vaccine.

Learn more here: upcoming blog post How are vaccines made?

Vaccine producers list everything used in the process of making a vaccine. Imagine reading the ingredients for a bag of peas if the food company had to list everything used to grow the peas. The list would include “soil,” “cow manure,” and the chemicals found in the fertilizers. In a similar way, many of the items listed as vaccine ingredients are used to create a vaccine, but are not in the final product.

Ingredients that people often have questions about are:

Aluminum Salts: These are used in some vaccines as an“adjuvant”-- an ingredient used to cause a better immune response to a smaller dose of the active part of the vaccine. An adjuvant with a smaller dose of active vaccine helps to create fewer side effects. The aluminum salt is absorbed from where the vaccine is given and leaves the body in our urine. Aluminum is a very common element; It is the third most common element in the Earth’s crust. We constantly eat, drink, and breathe it. The aluminum in vaccines is such a small amount compared to what we are exposed to in everyday life. It is cleared from the body so well that we can’t even detect a change in the amount of aluminum in the body after vaccination.

Learn more about aluminum in vaccines here: The Safety of Vaccine Ingredients: Part One (Aluminum) — Boost Oregon, Aluminum and Asthma — Boost Oregon, l

Video link: Why is there aluminum in vaccines? 

Thimerosal: This is a preservative that used to be in some vaccines to keep them sterile and safe. Thimerosal was removed from all childhood vaccines in 2001. Thimerosal breaks down into ethylmercury, which quickly leaves our body through our urine. Ethylmercury is safe, unlike methylmercury found in fish, which can be toxic at high levels.

Learn more about mercury in vaccines here: The Safety of Vaccine Ingredients: Part Two (Mercury) — Boost Oregon"

You can find more information about other vaccine ingredients here: The Safety of Vaccine Ingredients: Part Three (Formaldehyde & Other Ingredients) — Boost Oregon, 

What’s in Vaccines? — Boost Oregon

Before being approved for public use, vaccines must be safe and effective in studies with thousands of people. Study data is reviewed by agencies that manage vaccine safety and policy along with panels of experts to decide whether to approve a vaccine. No steps can be skipped.

After approval, vaccine safety is constantly monitored through many systems. That allows us to detect very rare side effects. 

Learn more about vaccine development here: Children’s Hospital of Philadelphia, Vaccines are Safe (and Save Lives) — Boost Oregon, How Are Vaccines Developed blog post (forthcoming), video: are vaccines safe?

Yes. Vaccines for new diseases are tested against a placebo-- a shot that does not have an active ingredient in it. As one of the early vaccines to be made, the MMR vaccine was even compared to people who had not been vaccinated because there were a lot of people who never had a vaccine at the time it was studied. When a new version of a vaccine is made, it is tested against the current version to ensure it is at least as effective and safe as the one that came before it.

All vaccines are very good at stopping the diseases they are created for. But, different vaccines have different levels of protection. For example, the measles vaccine is 97% effective at preventing measles infection. Protection with the vaccine lasts a lifetime. The tetanus vaccine is very protective, but needs booster doses over time to keep that protection. The flu shot is less effective at preventing minor illnesses, but it still protects against severe flu infection. The vaccine needs to be updated each year to keep up with how quickly the virus itself changes. Almost all of the 25,000-50,000 deaths from influenza in the US each year are unvaccinated (Vaccine Effectiveness: How Well Do Flu Vaccines Work? | CDC). Vaccines work best when community immunity is high enough to keep diseases from spreading.

Most people have few to no side effects after getting a vaccine. The most common side effect of vaccines is arm pain or stiffness. Less common side effects can include tiredness, headaches, fevers, and rashes, but almost always resolve in 1-2 days. None of the vaccines on the CDCs childhood immunization schedule cause any dangerous or long-term side effects.

Vaccine side effects are the body's natural immune response to a vaccine antigen. It is a sign that the vaccine is doing what it should. The vaccine signals your immune system to make antibodies against the vaccine antigen. Side effects are similar to what you may feel when your immune system responds to a disease antigen. Your immune system responds the same way to vaccines as it does to germs.

No. When we get a vaccine, our bodies respond to the antigen with a targeted immune response. Our bodies create antibodies and memory cells to protect us in the future. All vaccine ingredients are chosen with a purpose. They are materials that our bodies know how to process and we are exposed to everyday. Because of this, there are no known long-term problems caused by vaccines.

No. There is a lot of research into this question, and there is no data to show a connection between any vaccine and autism. Recent research studied very large populations of children (600,000 children and more). Even in families with risk factors or a history of autism, studies did not find a link between vaccines and autism.

Diseases that vaccines prevent cause much worse symptoms than vaccines. Illness can lead to severe health outcomes, including death. Childhood vaccine side effects can be unpleasent, but are not harmful like the diseases they prevent. Common vaccine side effects do not lead to severe health outcomes.

As vaccine science improves, we can prevent more diseases. More vaccines are a good thing. We can reduce our risk of catching other harmful diseases and avoid needing advanced medical care.

There is no benefit to getting sick. Whether you get a vaccine or get sick with a germ, your body is going to use its natural immune response. But, the body has to work much harder to create immunity from an infection. It must fight a wild germ that will multiply millions of times and spread. Vaccines allow us to use the smallest possible amount of antigen to prevent us from getting sick in the first place.

Most bacteria and viruses are not harmful to humans and help us survive. But, disease-causing germs are dangerous. There is no benefit to getting sick from disease-causing germs. We can vaccinate against them to avoid harm. People who catch a disease when they were not vaccinated are more likely to need antibiotics and other medical treatments. These treatments can actually harm germs that benefit us in the process of fighting the disease-causing germs. Thanks to vaccines, we can prevent dangerous diseases without harming our general health

No. MTHFR stands for methylenetetrahydrofolate reductase. It is an enzyme that is part of many processes in our bodies. There are several versions of this enzyme. Depending on which version you inherited from your parents, your enzymes may be more or less active. Many of us have a variation of this enzyme that is lower-functioning. Some argue that these genetic variations increase the chance of problems with vaccines. There is no evidence that an MTHFR gene variation causes negative reactions to a vaccine. There is no reason to avoid immunizations if you know you have an MTHFR gene variation. Because these variations are so common, it is not recommended to test for them at all.

People who had a serious allergic reaction to a vaccine should not get that vaccine in the future. A serious allergic reaction may include difficulty swallowing or breathing, or a sudden change in blood pressure. Those symptoms require immediate medical attention. 

People who are pregnant or have no immune system should not get live virus vaccines. Those vaccines are MMR, Varicella, and the intranasal flu vaccine.

People who had typical side effects from a vaccine can still receive that vaccine in the future. Those who had serious side effects should speak with their doctor about the risks and benefits of getting a vaccine.

People with a family history of severe allergies to vaccines are not known to be at a higher risk of those same side effects. It is still recommended that they be vaccinated. (The Vaccine Handbook. A Practical Guide for Clinicians. 11th edition. Gary S. Marshall, MD.)

When people choose to skip vaccines, the community vaccination rates go down. When rates are below levels needed for community immunity, people who are unable to get a vaccine are at risk of catching a disease. Vaccinating your child and yourself not only protects you and your loved ones, but everyone in your community.

Vaccines teach our bodies to protect against harmful germs. This prevents us from getting very sick and lowers the chances of needing medicines or going to the hospital. Every year, illnesses that vaccines help to prevent can still affect kids who haven't had those vaccines.

Learn more here: upcoming blog post Why do babies need vaccines?

Video link: why are vaccines given to babies?

Children do best with vaccines when parents are honest with them about what to expect. Parents should let their children know that shots can be scary and painful, but that they are safe and will be okay. It can help to hold them in a comfortable position, like a hug. You can request using a pain blocking tool like a Buzzy Bee or Shot Blocker to reduce the pain.

Yes. Vaccines greatly reduce the risk of getting sick and having severe illness from the diseases they target. But, no vaccine is perfect. For example, wearing a seat belt doesn’t guarantee you won’t get injured in a car crash. But, seat belts are the best way to keep us safe from getting very injured in a crash. In the same way, getting a vaccine doesn’t guarantee you won’t get sick. It is the best tool we have to keep us from catching and getting very sick from serious diseases.

Yes. Babies are exposed to far more antigens in a single day than over the course of the entire immunization schedule.

Yes. Parental antibodies from the placenta protect newborns from germs but disappear after about 6 months of age. Vaccines allow children to create their own natural antibodies to continue protecting them from germs as they grow. Delaying vaccines leaves children at risk for infection after parental antibodies disappear.

No. The CDC vaccine schedule shows the safest time for children to receive vaccines. Spacing out vaccines does not reduce side effects; it increases the time that children remain at risk for a disease. Changing the schedule often leads to more shots and more trips to the doctor’s office.

Learn more here: When Individual Doctors Make Their Own Immunization Schedules: What You Should Know | | Children's Hospital of Philadelphia (chop.edu),

Yes. Vaccines provide important protection for every child, no matter their health. No amount of healthy diet, exercise, sleep, or mental wellness will stop a germ from causing an infection. Vaccines are one of many important steps we can take to keep our children healthy.

Yes. The CDC’s childhood vaccine schedule is recommended for all children. Rarely, a child’s specific situation requires a different plan. Diseases that we vaccinate against are dangerous for everyone. Vaccines are the best protection we have.

Yes. Children with chronic medical conditions may be at higher risk for serious illness from diseases that vaccines prevent. It is important that they and everyone around them are fully vaccinated. Children who have immune systems that are very weak, like those with HIV or on chemotherapy, cannot receive live virus vaccines, like MMR and Varicella. For those children, all of their friends and family must be fully vaccinated to provide community immunity.

Yes. There is no harm in receiving a vaccine after having the disease it protects against. Some vaccines are not necessary if you've had the infection already. This is the case if an infection can provide lifelong immunity. In other cases, it is still recommended to get a vaccine even if you’ve had the disease. This may be because the infection does not provide long-term immunity. Or, there are other subtypes of the disease that could still cause future infection. If you are unsure whether your child had a disease before, it is always safer and recommended to get them vaccinated. (The Vaccine Handbook. A Practical Guide for Clinicians. 11th edition. Gary S. Marshall, MD.)

Yes. Childhood vaccines can safely be given numerous times. It is always preferable to avoid unnecessary shots. But, if you aren’t sure whether your child has gotten a vaccine before, it is safer to get the vaccine again. Another vaccine is better than risking them remaining unprotected.