How Do We Know Vaccines are Safe?
Aug 15, 2018

Vaccinate Your Family_MomGrandmaLittleGirlToo often, we hear misinformation about vaccines and their safety. Some people claim that they are not tested for safety before being licensed and recommended for use in people in the United States. Others say that vaccines are not held to the same safety standards as drugs, when in fact they are held to a higher standard. And some others wrongly proclaim that vaccines are not monitored for safety after they are licensed by the U.S. Food and Drug Administration (FDA) and recommended for the public by the Centers for Disease Control and Prevention (CDC), as they are unaware of the strong vaccine surveillance systems we have in place in the U.S.

The United States has the safest, most effective vaccine supply in its history.

Below, we offer an overview of how vaccines are tested and monitored for safety and effectiveness:

The Journey of Your Child's Vaccine

www.cdc.gov/vaccines/parents/infographics/journey-of-child-vaccine-h.pdf

Clinical trials

Vaccines are one of the most thoroughly tested medical products available in the U.S. Before a vaccine can be considered for approval by the FDA, a vaccine manufacturer must show it is safe and effective through clinical trials. Developing a new vaccine begins with exploratory stage and pre-clinical stage before advancing to three stages of clinical trials. Together, this scientific process can take over a decade and cost millions of dollars. The FDA then examines these studies and determines whether a vaccine is safe, effective, and ready to be licensed for use. The FDA only licenses vaccines that have data that shows that the vaccines’ benefits outweigh the potential risks. If there is any question about the data, or any holes in the data, the FDA will request further studies before approving the vaccine.

Four monitoring systems 

After a vaccine is licensed for use in the U.S., there are four systems in place that work together to help scientists monitor the safety of vaccines and identify any rare side effects that may not have been found in clinical trials. Even large clinical trials may not be big enough to find very rare side effects. For example, some side effects may only happen in 1 in 100,000 or 1 in 500,000 people. Second, vaccine trials may not include certain populations like pregnant women or people with specific medical conditions who might have different types of side effects or who might have a higher risk of side effects than the volunteers who got the vaccine during clinical trials.

Vaccine Adverse Events Reporting System (VAERS)

VAERS is a passive reporting system. That means it relies on individuals to report vaccine reactions. Anyone can report a reaction or injury, including healthcare providers, patients and patients’ representatives, such as caregivers or attorneys. The system is co-managed by the FDA and the CDC. However, it is important to note that VAERS data alone can’t be used to answer the question, “Does a certain vaccine cause a certain side effect?” This is because adverse events reported to VAERS may or may not be caused by vaccines. There are reports in VAERS of common conditions that occur just by chance after vaccination. Further investigation may find no medical link between vaccination and these conditions. Instead, the purpose of VAERS is to see if unexpected or unusual patterns emerge, which may indicate a vaccine safety issue that needs to be researched further.

The Vaccine Safety Datalink (VSD)

Established in 1990, VSD is a collaboration between the CDC’s Immunization Safety Office and eight health care organizations across the country. It conducts studies based on questions or concerns raised from the medical literature and reports to VAERS. In addition, when new vaccines are recommended or if changes are made in how a vaccine is recommended, VSD will monitor the safety of these vaccines.

The Clinical Immunization Safety Assessment Project (CISA)

CISA, which was created in 2001, is a national network of vaccine safety experts from the CDC’s Immunization Safety Office, seven medical research centers and other partners. CISA addresses vaccine safety issues, conducts high quality clinical research and assesses complex clinical adverse events following vaccination. CISA also helps to connect clinicians with experts who can help consult on vaccine safety questions related to individual patients.

The Post-Licensure Rapid Immunization Safety Monitoring System (PRISM)

PRISM is a partnership between the FDA’s Center for Biologics Evaluation and Research and leading health insurance companies. It actively monitors and analyzes data from a representative subset of the general population. PRISM links data from health plans with data from state and city immunization information systems (IIS). PRISM has access to information for over 190 million people allowing it to identify and analyze rare health outcomes that would otherwise be difficult to assess.

These four post-licensure monitoring systems have been able to address several important issues related to vaccines and their safety, including:

The Department of Health and Human Services (HHS) and its agencies, health insurance companies, scientists, healthcare providers, and other public health and medical groups are all dedicated to ensuring people of all ages are protected against serious infectious diseases by a safe, effective supply of vaccines.


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8 responses to “How Do We Know Vaccines are Safe?”

  1. […] has always produced first-rate material, but today it published an elegant post called How Do We Know Vaccines are Safe? which was informative, well-researched, and even beautiful to look at.    It goes through the […]

  2. doritmi says:

    Thank you for going through this.

  3. PD says:

    “The Department of Health and Human Services (HHS) and its agencies, health insurance companies, scientists, healthcare providers, and other public health and medical groups are all dedicated to ensuring people of all ages are protected against serious infectious diseases by a safe, effective supply of vaccines.”

    I’m sure the author is happy to explain why it is that a “Lawsuit Proves HHS Hasn’t Filed Required Vaccine Safety Reports with Congress IN 30 YEARS” (https://thefreethoughtproject.com/hhs-vaccine-safety-reports-lawsuit/).

    Well, have at it.

  4. doritmi says:

    I expect the author does not know why administrative reports were not filed with Congress – it could be a failure of the department and an equivalent failure of Congress to enforce, an agreement with Congress that something else count as the reports – like reports of the IOM, lack of funding, or it could be that reports were filed but not found (Vince Ilaneli from Wikipedia found one such report: https://vaxopedia.org/2018/07/22/did-the-us-government-lose-a-landmark-vaccine-lawsuit/).

    It’s unlikely the author can figure out which of these is the actual option – HHS is your address. It doesn’t change the evidence vaccines are safe, or the reality that many of HHS agencies and staff put a lot of effort into that, justifying the description above.

  5. Joel A. Harrison, PhD, MPH says:

    @ PD

    First, I’d like to thank doritmi. Good find, VAXOPEDIA article. I just downloaded and added it to my collection.

    Just to add that even if the reports weren’t made to Congress, as you wrote, doesn’t mean the studies weren’t done. One can go to CDC Vaccine Safety Publications webpage which lists publications by year and also links to their various vaccine safety surveillance systems at:

    https://www.cdc.gov/vaccinesafety/research/publications/index.html

    The above lists only studies directly funded by CDC. To find more studies, lots more, one can go to PubMed at:

    https://www.ncbi.nlm.nih.gov/pubmed/?term=vaccine+safety

    Type in “Vaccine Safety” and you get 18,005 papers. One can also type in more specific searches, e.g., “MMR vaccine” AND autism which found 167 papers. And, of course, some of the papers will find safety problems. As I have written in papers and comments, we don’t live in a perfect world. The best we can do is look at Benefits/Cost ratios. The minuscule risks of serious adverse events from vaccines pales in comparison with the risks from the actual natural diseases. In addition, since any reaction has a genetic component, at least some kids who react to a vaccine, a killed or seriously weakened version of a microbe, would have also reacted to the natural microbe. And despite what antivaccinationists choose to believe, kids get far more aluminum from breast milk and other environmental sources than vaccines and thimerosal has been removed from all vaccines except flu vaccine and one can get thimerosal-free flu vaccine, despite studies finding no link between thimerosal and adverse events and the amount of the far more toxic form of mercury, methyl mercury, we are exposed to in higher amounts from the environment. And finally, some of the studies that found adverse events were poorly designed or, even if well-designed, random chance could have affected the result. As an example, imagine one does a case-control study comparing those who experienced an adverse event following some vaccine and those who didn’t. One tries to hold all other factors/variables constant that might affect the outcome; e.g., equal number of boys and girls, within narrow age range; but, for instance, what if the two groups differ in some key factor not controlled for, e.g., previous illnesses, nutrition, genetics (more Northern Europeans in one group)? This is why those trained in science don’t rely on one or two papers; but look at methodology, including sampling, etc and all the related studies. Antivaccinationists jump on anything that finds a negative; but if later research shows it to be wrong, I’ve never seen on any antivaccinationist blog a mea culpa. I remember more than 30 years ago a paper in the prestigious New England Journal of Medicine finding a link between coffee/caffeine and pancreatic cancer. It was in ALL newspapers. Well, I didn’t stop drinking coffee and the paper was found to be incredibly flawed. Convert an antivaccinationist to an anticaffeinist and to this day their websites would be railing about the evils of caffeine. At least being against caffeine wouldn’t put kids at risk!

    And the alleged link between vaccines and autism has been refuted by over 15 papers, research conducted on different populations, in different nations, by different researchers. When antivaccinationists can’t find significant flaws in the research, they resort to ad hominem attacks, to a belief in some world-wide conspiracy to further the “profits” of the pharmaceutical industry, despite vaccines representing only 2% of pharmaceutical industries world-wide revenues, and only a couple of companies a larger percentage. And, to the best of my knowledge, every provaccinationist researcher, including colleagues at CDC, have made sure their kids got all their shots. I’m sure there are a few who didn’t. An old saying: “The exception proves the rule.”

    And, many of the topics, fears of antivaccinationists, have been reviewed by the Institute of Medicine, each study with huge references lists which can be found at:

    http://nationalacademies.org/hmd/Reports.aspx?filters=inmeta:activity=Immunization+Safety+Review

    Note that all can be downloaded as pdfs for free, simply sign up.

  6. PD says:

    “I expect the author does not know why administrative reports were not filed with Congress….”

    And you do? Well, do tell.

    “It’s unlikely the author can figure out which of these is the actual option….”

    Well, do tell…again.

    The failure of the HHS to report as duly authorized does, regardless of what anyone believes
    about HHS, et al., speak to a lawful, vaccine-related failure. Are there other vaccine-related failures that have occurred? I’d like to know.

    But you seem to be so enamored with HHS, vaccines or whatever that you’re unwilling to even question the possibility that something sinister might be the case.

    It’s really difficult to have a reasonable and intelligent conversation (or any conversation at all, actually) with someone who isn’t open to possibilities that are opposed to their deeply held position, erroneous or not,

  7. Joel A. Harrison, PhD, MPH says:

    @ PD

    No, I don’t know why the reports weren’t either filed and/or misplaced. However, with an undergraduate dual major, Political Science and Psychology, from over 50 years ago, I know from courses then and later readings that it isn’t just vaccine safety reports that are not filed or misplaced. You are typical of antivaccinationists, single out something related to vaccines as if they are treated differently. Well, actually they are treated differently, the requirements for FDA approval and post-marketing surveillance and mechanisms make vaccines either the safest product on the market or among a select few. What sinister could be the case when I gave you links to websites where umpteen studies of vaccine safety appear? All they had to do is summarize the studies, the funding, and submit it. Why they didn’t or they were misplaced, no idea, except for bureacracies don’t alway reflect best on the work being carried out by an organization; but proof is in the pudding and the studies have been carried out and reported. Have you ever heard the phase: “Hiding in plain sight?”

    As for “It’s really difficult to have a reasonable and intelligent conversation (or any conversation at all, actually) with someone who isn’t open to possibilities that are opposed to their deeply held position, erroneous or not.”

    It is you who are closed minded, ignoring the fact that the required studies were done and easily accessed. I am open to all reasonable possibilities. I have NEVER worked for the CDC, FDA, NIH, nor any pharmaceutical company, nor do I own stocks in them. However, I have spent 50 years reading about the history of infectious diseases, studied epidemiology, immunology and microbiology, monitor websites for CDC, WHO, Canada, France, Sweden, so, up-to-date on diseases still raging around the world, but a plane flight away, and quite simply get tired of antivaccinationists jumping to conclusions, always negative ones. I am keenly aware of adverse events with vaccines and choose not to reject vaccines because I am also aware of the much greater harm that would come from a world without vaccines. In fact, without the smallpox vaccine, we wouldn’t have to worry about global population, good chance neither of us would exist as smallpox alone killed an average of 30% of population. I look at benefit/risk ratios and vaccines win hands down.

    Please explain whatever sinister meaning you attribute to the reports not being available; but make sure you include that the actual studies are easily accessed.

  8. Chris says:

    PD: “The failure of the HHS to report as duly authorized does, regardless of what anyone believes about HHS, et al., speak to a lawful, vaccine-related failure. Are there other vaccine-related failures that have occurred? I’d like to know.”

    Well, did you know that the HHS a government department of the United States of America and no other countries? Here is something you need to know: vaccines are studied and used in other nations. What is really cool is that their studies also show very similar safety data for vaccines.

    Instead of hinting at nefarious intentions (or conspiracies), what you need to do is provide the PubMed indexed studies by reputable qualified researchers that any vaccine on the present American pediatric schedule causes more harm than the disease. Folks like you seem to forget there is a very real reason why the vaccines were developed in the first place. The diseases can cause very real harm and suffering, I know that from personal experience.

    If you are still thinking vaccines cause autism, well I have some news for you: the causes of over half of the cases of autism have been discovered! Also there is a hunt to find more genetic sequences to fill in the gap: https://sparkforautism.org/discover/

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