written by Tara Haelle

This news came out last week, but in the flurry of other health-related (especially vaccine-related) news, I haven’t had a chance to get around to it except my story at dailyRx. As you may have already heard, the Institute of Medicine (IOM) published a report last Wednesday affirming the safety of the CDC’s childhood immunization schedule.

Ok. Cool. So what exactly does that mean?

I’ll give you the spoiler first, and then give you the nitty gritty. The spoiler: this is big, big, big news. This is the first time the IOM has reviewed the entire current childhood vaccination schedule and given it a thumbs up for safety. If you’re a parent, this news either tells you what you already knew, or it should significantly reassure you if you had concerns about the safety of the schedule.

Okay, now let’s back up. To understand why this report is so important, it’s important to understand what the Institute of Medicine is. As the health branch of the National Academy of Sciences, the IOM is independent and nonprofit — and it also works outside of the government. All three of those facts are extremely important when considering that the organization is approving the safety of the childhood vaccine schedule (which has often been questioned by concerned but generally misinformed or confused parents).

Further, the committee members who review the evidence to make their assessments are not all necessarily experts specifically in the field in question and are “selected to avoid any real or perceived biases or conflicts.” That means the 14 committee members are not all vaccine researchers, pediatricians or infectious disease epidemiologists. In the report’s appendix, you can read the bios of all the committee members, who include a nursing professor, a biostatistician, a professor of law and bioethics, a doctor specializing in allergies, and an economist, as well as pediatricians and epidemiologists.

They also have not received funding, grants, honoraria, speakers’ fees, travel funds or other compensation from pharmaceutical companies. The report notes, “Strict criteria for membership prevented members from having financial ties to vaccine manufacturers or their parent companies, previous service on federal vaccine advisory committees, or having delivered expert testimony or written publications on vaccine safety.” (Interestingly, a few years ago, the IOM issued a report warning doctors of the potential conflicts of interest that arise when they’re too cozy with Big Pharma.) So, the usual charges by anti-vaccine advocates that promoting vaccines involves a profit motive or a conflict of interest due to pharmaceutical funding cannot apply here. (The government’s lack of involvement means the really crazy ones who think it’s a government-funded conspiracy are out of luck too.)

When the IOM issues a report, the committee reviews all of the research that’s out there. They talk to ALL the stakeholders: researchers, advocacy groups, government groups (including committees like the CDC’s Advisory Committee on Immunization Practices), parents, nurses, doctors, pharmacists, nongovernmental organizations, international organizations, the media, pharmaceutical companies, private investors, insurance companies, philanthropic organizations (like the Bill and Melinda Gates Foundation), vaccine-related distributors… EVERYONE.

In Appendix E of the report, the IOM committee has listed many of the people they met with, including Bruce Gellin, the director of the National Vaccine Program Office at the US Department of Health and Human Services, and Barbara Loe Fisher, co-founder and president of the (inaccurately named) National Vaccine Information Center — otherwise known as the granddaddy of all anti-vaccine organizations and purveyor of misinformation and fear-mongering. They also spoke to leading epidemiologists in the field of vaccine research, such as Dr. Jason Glanz at Kaiser Permanente Colorado and Dr. Saad Omer at Emory (University) Vaccine Center.

In short, the IOM conducts about the most thorough and unbiased review you could possibly ask for. The Institute has already issued several dozens of reports in the past forty years about vaccine safety, from discussing the use of the preservative thimerosal in vaccines to investigating various adverse events linked (or not linked) to certain vaccines.

The IOM is truly the gold standard in assessing medical questions based on the current research.

In this report, the IOM took up study of the CDC vaccination schedule because there has been concern in some circles that kids get too many shots too soon. The 14 diseases that the current schedule protect against mean kids get up to 24 shots by the time they turn 2, including up to five shots in one visit sometimes. It does sound like a lot. It *literally* sounds like a lot if your kiddo is a crier. But that’s only part of the story. As the IOM notes in its introduction, “Technological advances have reduced the number of antigens—that is, inactivated or dead viruses and bacteria, or altered bacterial toxins that cause disease and infection—in vaccines.” Antigens are what usually cause most adverse reactions, and they’ve dropped from over 3,000 in 1980 to fewer than 130 in 2000.

Still, parents have worried about the additives in vaccines, such as aluminum (an “adjuvant” used to enhance the immune response) and thimerosal (a preservative now only found in some multi-dose flu shots). So, the IOM looked at all the research, talked to all the stakeholders and have now concluded that they found “no evidence that the schedule is unsafe.” Specifically, “the committee’s review did not reveal an evidence base suggesting that the U.S. childhood immunization schedule is linked to autoimmune diseases, asthma, hypersensitivity, seizures, child developmental disorders, learning or developmental disorders, or attention deficit or disruptive disorders.”

From here, the IOM committee identified the different ways in which vaccine safety is monitored in the U.S. and considered additional research that can and should be done. They note that vaccines are “neither 100 percent free of risk nor 100 percent effective.” However, they also note how rare serious illnesses caused by vaccinations are and how effectively vaccines have reduced disease in the U.S. (in some cases to zero (smallpox) or almost zero (diphtheria) cases).

Importantly, the committee noted that doctors need to do a better job of communicating to parents the actual (very low) risks and the safety of vaccines. “The committee recommends that the National Vaccine Program Office systematically collect and assess evidence regarding public confidence in and around the concerns of the entire childhood immunization schedule with the goal to improve communication — communication with healthcare professionals and between healthcare professionals and the public — regarding the safety of the schedule,” said committee head Ada Sue Hinshaw, RN, PhD, on a media conference call.

In discussing the existing ways to investigate vaccine safety, the IOM committee mentioned FDA monitoring programs as well as the Vaccine Adverse Event Reporting System (VAERS) and the Vaccine Safety Datalink (VSD). VAERS is the database where adverse events occurring after vaccination can be reported for investigation, though it’s worth noting that just because something is submitted to VAERS doesn’t mean a vaccine caused it. The IOM notes that the VSD, established in 1990, is the most effective tool currently available to study specific vaccine safety concerns. It tracks demographic, medical, and vaccination information for over 9 million children in nine managed care organizations throughout the U.S., including whether they get their shots on the regular CDC schedule or alternative schedules. It’s also frequently used for a data sets in vaccine safety studies.

Finally, the IOM addressed a request commonly heard in anti-vaccine circles: Can we do a long-term study comparing fully vaccinated children to unvaccinated children? No, the IOM said, they do not endorse such a study. Doing a randomized, controlled clinical trial like that would be unethical for two reasons. First, it leaves the unvaccinated children at risk for getting the diseases the vaccines protect against. Second, a truly randomized study might mean some kids get vaccinated when their parents don’t want them vaccinated while other kids don’t get the vaccines even though their parents want them protected.

So what about a long-term observational study? First, observational studies are less reliable in finding problems or differences between groups since there are other underlying differences in those who choose not to be or cannot be vaccinated versus those who are fully vaccinated. Second, it costs a lot of money to do such a study when the results would be of limited use. Third, less than 1 percent of Americans refuse all vaccines, the IOM notes, so finding and matching each of those 1-percenters to vaccinated children of the same age, race/ethnicity, geography, family income, etc., would be incredibly difficult and time-consuming, if not impossible. Of course, I prefer the answer I got from Art Caplan, the director of the Center for Bioethics at the University of Pennsylvania, during an interview once: “Here’s the uncontrolled vaccine population: sub-Saharan Africa, poor-world India, poor-world China, and vast areas of Central and South America. Babies are dying in droves from infectious diseases.”

The IOM stated that the existing mechanisms, especially the Vaccine Safety Datalink, are sufficient for looking into specific vaccine safety concerns. They encourage further study, but the crux of their findings should be reassuring to reasonable parents who have questions or concerns about how many shots their kids get following the CDC schedule: “In this most comprehensive examination of the immunization schedule to date, the IOM committee uncovered no evidence of major safety concerns associated with adherence to the childhood immunization schedule, which should help to reassure a diverse group of stakeholders. Indeed, rather than exposing children to harm, following the complete childhood immunization schedule is strongly associated with reducing vaccine-preventable diseases.”