Frequently Asked Questions

Some vaccines contain aluminum salts because they are an effective adjuvant (a “booster” ingredient that helps a vaccine produce a stronger immune response so the vaccine works better). They have been used in vaccines for nearly a century without any apparent safety issues in that time.

Aluminum is naturally found in fruits, vegetables, meats, and fish – that’s because it’s the 3rd most abundant element on earth. The amount of aluminum found in vaccines is well within safe limits. For example, the amount of aluminum infants receive from vaccines in their first 6 months is about 4.4 mg. During the same six months, a breast-fed baby will typically receive more than twice the amount in a vaccine from their mother’s milk.

Some multi-dose vials of vaccines contain a type of mercury called ethylmercury, found in a compound called thimerosal, because it prevents dangerous microbes from growing in the vials once they are opened. In the past, before the use of thimerosal, there were tragic instances of people developing sometimes fatal infections after vaccination because of contamination of the vial. There has been concern about thimerosal because some people have confused it with a type of mercury (methylmercury) often found in fish, that can build up in your body and produce toxic effects at high doses. Ethylmercury, which is produced from thimerosal in the body, on the other hand, breaks down and is excreted from the body rapidly.

Many chemical compounds have complex and unfamiliar names that can confuse or concern people, even if they’re things we deal with on a daily basis. Thimerosal is actually an organic compound and has been used in vaccines, other drugs, and contact lens solution since the 1930s. Today, none of the childhood vaccines on the schedule contain thimerosal because vaccine manufacturers have found cost-effective ways to make single-use vials, but it is still found in some multi-dose flu vaccines. Thimerosal has been rigorously studied in the United States and many other countries and no apparent safety issues have been found, but for people who still have concerns about it, there are thimerosal-free vaccines available.

Formaldehyde is a naturally occurring compound. In fact, formaldehyde is essential in human metabolism and necessary for helping the body use DNA and amino acids. All people have detectable amounts of formaldehyde in their system.

Formaldehyde is also used when making vaccines to make sure the viruses or bacteria in the vaccine are inactivated and don’t cause sickness. Most of the formaldehyde is diluted during the process, but a trace amount may still be found in some vaccines. The amount of formaldehyde found in vaccines is safe and far less than what is found naturally in the body. An infant naturally has about 1500 times the amount of formaldehyde in their bloodstream than what is found in a vaccine.

Adjuvants help your body produce a stronger immune response, which means greater protection against a disease. Using adjuvants also means the immune system can produce more antibodies and longer-lasting immunity, so a smaller amount of the antigen needs to be used in the vaccine. Adjuvants are also critical in ensuring that the immune response is protective; if some antigens are introduced into the body without the addition of an adjuvant the immune system may instead learn to tolerate the antigen rather than work to combat it.

Adjuvants have been used in vaccines since the 1930s. Millions of Americans have safely received vaccines with adjuvants for decades. Like all vaccines, adjuvanted vaccines are rigorously tested in clinical trials to ensure they are both safe and effective. Once they are approved in the U.S. adjuvanted vaccines continue to be monitored by the CDC and FDA.

No, vaccines do not contain aborted fetus cells. The viruses used in vaccines are sometimes cultured in human cells, but there are two important things to know about these cells:

• “Cultured in” is not the same as containing. Think about culturing as a garden. Often gardeners will use compost to help their vegetables grow. But when they eat the vegetables they have grown; they are only eating the vegetables and not the compost. Vaccines are similar to vegetables and what they are cultured in is similar to the compost. It helps them grow but is not in the vaccine.
• The cells originally used for culturing some viruses came from two terminated pregnancies in the 1960s. The cells today are cultured in labs: a good way to think about them is that they are the great, great, great grandchildren of the original viruses that were grown in the 1960’s terminated pregnancies cell line.

Based on the concepts of “v’chai bahem” (which means you should live by the mitzvot or Torah commandments) and “pikuach nefesh” (holding saving a life as sacrosanct) most Hebrew scholars consider vaccines 100% kosher.

This question originally came up because of the gelatin used in some vaccines as a stabilizer. While this gelatin is porcine-derived (came from pigs), a vaccine is highly purified during manufacturing and is not taken orally. Jewish law has restrictions about non-kosher foods but does not forbid non-kosher products as long as they are not swallowed.

Some Muslim communities have questioned whether vaccine ingredients are halal. This concern has come up with some polio vaccines that are cultured in monkey cells. Think about culturing as a garden. Often gardeners will use compost to help their vegetables grow. But when they eat the vegetables they have grown; they are only eating the vegetables and not the compost. Vaccines are similar to vegetables and what they are cultured in is similar to the compost. It helps them grow but is not in the vaccine.

Most well-known Islamic religious scholars have issued Fatwahs (an Islamic scholar’s ruling) stating that vaccination is part of the Islamic duty to protect children.

No. Vaccines are not big profit-makers for pharmaceutical companies. In fact, most of their profit is from selling drugs that treat diseases (including those prevented by vaccines).

Like any business, pharmaceutical companies must make enough profit from vaccine sales to justify investing the huge amounts of money, effort, and time it takes to develop vaccines. Vaccines can take up to 15 years to research and test. It costs a lot to produce and distribute vaccines, but they have limited demand (just a few doses) compared to other medicines. They are also heavily regulated. In the past, vaccines were so unprofitable that some companies stopped making them altogether.

Once global demand for vaccines began to grow in 2000, more pharmaceutical companies started making vaccines. The current global vaccine market is about $35 billion, which is less than 3% of the over $1.25 trillion global pharmaceutical market. To put this in perspective, the complementary and alternative medicine market (which includes mainly untested products and supplements) was $192 billion in 2018. Key Resources to learn more:

• Lancet Article: Estimating the Cost of Vaccine Development
• Atlantic Article: Vaccines Are Profitable, So What?

The US Government, specifically the Centers for Disease Control and Prevention, does not hold any patents on vaccines. This disinformation twists CDC’s altruism to ensure important biologics are accessible to scientists for free. Purdue University Biological Sciences Professor David Sanders explains it this way, “The CDC does hold some patents on life forms, but it generally does this for the common good, so a commercial company can’t come along and patent it. The CDC lets researchers work with the strain without fees.”

While there are some religious sects and leaders who have concerns about vaccination, no major religions prohibit vaccines. Some people use sincerely held religious beliefs to create concerns about vaccines. Some of these concerns span religions including Christianity, Islam, and Judaism. But the fact is that leaders across religions have all supported vaccination as part of their religion’s calls to care for others.

There are very few Christian sects that oppose vaccination because they believe only in faith healing, including Church of the First Born, End Time Ministries, Faith Assembly, and Faith Tabernacle.

Key Resources to learn more:

• Vanderbilt University Medical Center: Immunizations and Religion
• Vaccine Article: What the World’s religions teach, as applied to vaccines

They aren’t. As the anti-vaccine movement started to grow in the 1980’s there was an increase of frivolous lawsuits against vaccine manufacturers. The time and money it took to fight these lawsuits made it difficult for the manufacturers to continue to invest in new vaccine development as well as manufacturing and distribution. The concern was companies would not be able to make vaccines, leading to dangerous outbreaks, particularly among the most vulnerable in our communities.

In order to protect vaccines as a critical public health intervention, the government passed the 1986 National Childhood Vaccine Injury Act and created the National Vaccine Injury Compensation Program (VICP). This program both protects vaccine manufacturers against frivolous lawsuits and provides an easier process for legitimate potential injuries. Now, any individual can file a petition without fees. They do not have to provide evidence of vaccine defects. There is a much lower bar to prove evidence of injury if that injury is included on what is known as the “table of injuries.” If someone is denied a claim through the VCIP, they may then sue the vaccine manufacturer directly. Additionally, a vaccine manufacturer can always be sued if there were problems with the manufacturing process or if the vaccines were improperly made.

No, doctors are not punished for speaking out against vaccines.

However, doctors do have ethical responsibilities that include providing medical advice based on accurate, scientific information and following evidence-based standards of care. Immunization is a standard of care supported by decades of scientific research and careful review by thousands of medical experts. If a doctor provides vaccine disinformation that leads to someone becoming seriously ill or disabled, or provides inappropriate medical exemptions for vaccination, they could face legal charges and be investigated by state medical boards.

Some insurance companies provide bonuses for high vaccine rates because preventing disease is much less expensive for them than treating disease. Knowing that doctors have limited time with patients, insurance companies want to encourage doctors to prioritize preventative care, like vaccines. Vaccine manufacturers do not offer any bonuses for high vaccination rates.

The immune system works in two ways: 1) by remembering diseases it has seen to fight them off quickly and 2) by triggering the body’s defense mechanisms (such as fever and sneezing) to get rid of a new invader in the body. Vaccines teach the immune system how to remember diseases, but no supplement can do this work. Additionally, there is no evidence to support that supplements trigger better defense mechanisms in the body.

There’s also something to be said for not boosting the immune system. People who eat well and live generally healthy lifestyles, and do not have any conditions that can weakened immune system already have well-functioning immunity that needs no boosting. An overactive immune system can cause issues such as allergies and autoimmune disorders.

Yes, all diseases we vaccinate against can cause serious illness, disability, and even death, especially for young children. There is no way to tell ahead of time if a person will get a mild or severe case.

Even diseases that people think are mild can be very serious:

• Chickenpox (varicella) can have serious complications like pneumonia, encephalitis, and bloodstream infections. Before the vaccine, chickenpox sent 10,000 people in the U.S. to the hospital every year. It can also lead to shingles later in life, which can be very painful and cause long term nerve damage. It is additionally one of the most important causes of pediatric stroke.
• Flu (influenza) can lead to pneumonia, bronchitis, heart attacks, and other infections. For people with chronic health problems, it can make their conditions worse. About 30,000 Americans die from flu every year.
• Pertussis (whooping cough) can lead to pneumonia, seizures, brain damage, and death.

Visit Vaccines & Vaccine Preventable Diseases to learn more.

It can be difficult to know if a scientific finding is legitimate because unless you are a vaccine expert, the studies can be hard to understand and evaluate. Also, there are “junk” journals that publish sub-standard research – these journals may look legitimate but experts would not publish in them. The best way for parents to ensure the information they are looking at is good is to ensure the source is legitimate – a hospital, university, or government agency are all places for credible information.

Some helpful hints to determine if a website is trustworthy:

• Is it free of advertising? Most legitimate sources will not “hawk” products.
• Is it reviewed by experts in the field? Experts are scientists, doctors, and public health advisors who specialize in vaccines
• Does it provide sources for its information? A credible website will tell you where it got its information and those sources will be experts in the field.

Key Resources to learn more:

• CHOP Evaluating Information: What You Should Know
• CHOP Logical Fallacies and Vaccines: What you should know
• IAC Reliable Sources of Immunization Information

Formaldehyde is also used when making vaccines to make sure the viruses or bacteria in the vaccine are inactivated and don’t cause sickness. Most of the formaldehyde is diluted during the process, but a trace amount may still be found in some vaccines. The amount of formaldehyde found in vaccines is safe and far less than what is found naturally in the body. An infant naturally has about 1500 times the amount of formaldehyde in their bloodstream than what is found in a vaccine.

Yes, the fact that vaccines are safe and effective is agreed upon by every credible medical authority in the United States and across the world. Almost every scientist who studies vaccines agrees with those authorities.

Vaccines are studied and tested more than other medical intervention. After they are approved for use, scientists continue to monitor vaccines in the rare case a serious adverse reaction should be discovered. To give a sense of how rare these cases are, only 1 in 1 million doses of vaccines might have a serious adverse reaction.

Because so much time and effort is devoted to studying vaccines and because scientists agree that they are safe and effective, we consider the science around vaccines to be settled.

Scientists can only prove what things ARE by studying what they observe. They cannot prove what things are NOT because things that are not, cannot be observed.

For example, a scientist cannot prove that something, say a unicorn, does not exist. They can only say that during their comprehensive research they have not observed any unicorns. But if a scientist DID see a unicorn they could definitely prove the existence of a unicorn. Now they may have millions of data points so they are confident that a unicorn doesn’t exist but they still won’t say definitively because you can prove the existence of what you can’t observe.

It’s the same for vaccines. In millions of instances, scientists have not observed any evidence that vaccines cause autism. So even though they are 99.999% certain, the rules of science mean that they will only say that they have no evidence to support that hypothesis.

This can be a good way to identify legitimate vs fake science. No legitimate scientist will say with 100% certainty that they can prove a negative (something they didn’t observe) and any “scientist” that claims to prove a negative will likely be criticized by their peers for breaking the rules of science.

Some vaccines contain aluminum salts because they are an effective adjuvant (a “booster” ingredient that helps a vaccine produce a stronger immune response so the vaccine works better). They have been used in vaccines for nearly a century without any apparent safety issues in that time.

Aluminum is naturally found in fruits, vegetables, meats, and fish – that’s because it’s the 3rd most abundant element on earth. The amount of aluminum found in vaccines is well within safe limits. For example, the amount of aluminum infants receive from vaccines in their first 6 months is about 4.4 mg. During the same six months, a breast-fed baby will typically receive more than twice the amount in a vaccine from their mother’s milk.

Seizures in children are generally caused by two things:

• Fever: Fevers can be common in children, and sometimes they result in temporary seizures, called febrile seizures. These are usually harmless and require no treatment. Some children get fevers after vaccination as part of the natural process of their body building immunity, and these febrile seizures can occur. Post-vaccine febrile seizures are rare. They tend to only occur in young children and infants, and do not cause lifelong seizure disorders. Children usually grow out of them by about age 5.
• Genetic Disorders: Disorders such as Dravet Syndrome and other genetic epilepsies can also cause seizures. These can be lifelong disorders. In extremely rare instances vaccines can trigger Dravet Syndrome. But the reality is that unfortunately these children were likely going to get Dravets anyway due to their genetics.

The 1998 study that started this disinformation was investigated and found to be untrue. The doctor who led the study misrepresented the data and was found guilty of scientific misconduct. He lost his license to practice medicine, the paper was removed from the scientific record, and his co-authors took their names off the paper.

Since then, there have been hundreds of valid studies involving thousands of children in many countries looking at whether there is a connection between autism and vaccines. None of these studies has found any connection.

Two important studies include:

• 1999 Brent Taylor study that compared children with autism and children without autism. The study found that the percentage of vaccinated children was the same in both groups.
• 1991-1998 Denmark study by Madsen that included 537,303 children for a total of 2,129,864 person-years. The study found the risk of autism was the same in vaccinated and unvaccinated groups.

Here is a summary of studies looking at vaccines and autism sponsored or led by the CDC: https://www.cdc.gov/vaccinesafety/00_pdf/CDCStudiesonVaccinesandAutism.pdf

Ninety percent of SIDS deaths happen before a child is six months old. That is the same age when most children receive their DTaP series of vaccinations. Because of the similar timing, some people think vaccines cause SIDS. However, there is no link between the two. Many studies have been done in the last 20 years and none of them found a link between childhood immunizations and SIDS. In fact, several studies found children who recently received DTaP vaccines were less likely to die from SIDS. SIDS death investigations often find evidence of asphyxiation, meaning the child suffocated. The most common cause of SIDS-related asphyxiation is unsafe sleep practices such as blankets and toys in the crib, placing a child on their stomach to sleep, or bed-sharing with a parent. SIDS cases have dropped since safe sleeping campaigns (ABC: Alone, on their Back, in a Crib) began.

For a list of research and links to journal publications visit: https://www.cdc.gov/vaccinesafety/concerns/sids.html#rel

Pregnant people have been getting vaccinated for decades, keeping themselves and their unborn babies safe. There is a large body of research that has looked to see if there is any connection between vaccines and miscarriage and no link has been found. One study looked at flu seasons from 2012 to 2015 and found NO increased risk for miscarriage after influenza vaccination during pregnancy.

Not only are vaccines safe during pregnancy, but certain vaccines that those who are pregnant get can also provide immunity to their newborns. For example, if someone gets TDaP when they are between 27 and 36 weeks pregnant, their newborn will have some immunity to whooping cough, which is serious and sometimes deadly for babies. You can read the above referenced study here.

Recently, there has been some misinformation about vaccines and autoimmune issues. Some people incorrectly believe that because vaccines “train” the immune system to target pathogens, vaccines could also cause the immune system to target itself. But that’s not how vaccines work. Vaccines are “custom-made” to fit a specific pathogen to help the immune system recognize and fight it. They are like a puzzle piece–vaccines will not work unless they fit exactly.

While there have been some rare examples of Guillain-Barre Syndrome (GBS) following vaccination, studies generally show that there is no connection between vaccines and autoimmune diseases. The cause of GBS is not known but often occurs after a viral or bacterial infection. In some years, there have been GBS cases after the flu vaccine. However, it is important to understand the real risk. The studies show GBS after the flu vaccine occurs in 1-2 people out of 1 million vaccinated. But GBS after getting the flu occurs in 17 people out of 1 million infected. So, the risk of GBS is lower in vaccinated people compared to those who get the flu and because the flu vaccine prevents flu, a reasonable case could be made that it ultimately has a preventive effect against the development of GBS for most people. Key Resources to learn more:

• Lancet – Vaccination and autoimmune disease: what is the evidence?
• Children’s Hospital of Philadelphia – Vaccines and Autoimmune Disease

This disinformation is another attempt to convince people that vaccines cause autism. The history of this false hypothesis stems from Andrew Wakefield’s discredited research. Wakefield falsely claimed that the measles vaccine virus was found in the intestines of autistic children. No scientist was ever able to recreate these findings and Wakefield’s paper has since been retracted and he lost his license to practice medicine because of his fraud.

What is true is that people with damage to their gut (from malnutrition, infectious disease, or overuse of antibiotics) are not always able to produce as strong an immune response from vaccines as healthy people. Additionally, there are vaccines that promote gut health. For instance, Hepatitis vaccines actually prevent some types of hepatitis that can damage the liver and affect gut health.

There have been a number of studies that show that good gut health is important in helping vaccines do their job. You can read one study here.

Vaccines are continually monitored even after approval, and the data show us that most vaccine side effects happen hours or days after vaccination, are minor, temporary, and go away on their own. In a very small number of cases, we have found extremely rare side effects after approval. We only find these side effects because they are so rare that millions of people must be vaccinated for even one of them to show up. If these side effects were long-lasting, we would find them through this ongoing monitoring.