Ask SciMoms: Where does the vaccine schedule come from?

The current vaccine schedule can seem overwhelming and many parents consider following an alternate vaccine schedule. Here, we explore the Childhood Immunization Schedule. How does the CDC determine the recommended schedule? Who sets the recommended schedule? Where do alternate schedules come from?

CDC vaccination schedule shown in yellow, green, and purple.
Who sets the vaccine schedule and why are there so many?

Kids today get more shots that protect against more diseases than we did when I was a kid. Layla recently wrote about why kids get so many shots. In that piece, she explained why it is important to stick to the CDC’s recommended schedule (or your country’s equivalent) and why choosing a delayed scheduled increases risks.

Ignoring the CDC’s recommended schedule to spread out shots is risky because:

  • The schedule you pick will not have been tested. You are giving up a schedule that is supported by thorough testing and clinical trial data for a schedule that has little data to support it.
  • By delaying vaccinations and spreading them out, you increase the risk that your child will encounter the virus without having built up sufficient immunity.
  • There’s data suggesting that delaying vaccinations increases the risk of febrile seizures after vaccination.
  • In short, there’s no real benefit in delaying vaccinations, only added risk.

In this post, we will explore where this schedule comes from.

Who determines the vaccine schedule?

The Advisory Committee on Immunization Practices (ACIP) is a group within the CDC that is responsible for developing vaccine recommendations for the civilian population in the US. According to the ACIP charter:

The ACIP includes 15 voting members responsible for making vaccine recommendations. The Secretary of the U.S. Department of Health and Human Services (DHHS) selects these members following an application and nomination process. Fourteen of the members have expertise in vaccinology, immunology, pediatrics, internal medicine, nursing, family medicine, virology, public health, infectious diseases, and/or preventive medicine; one member is a consumer representative who provides perspectives on the social and community aspects of vaccination.

In addition to the 15 voting members, ACIP includes 8 ex officio members who represent other federal agencies with responsibility for immunization programs in the United States, and 30 non-voting representatives of liaison organizations that bring related immunization expertise.

Members and representatives serve on the Committee voluntarily.

A list of current members (voting and ex officio) is provided on the CDC/ACIP website at the above link. ACIP meetings are open to the public and are available online. You can find the schedules, agendas, minutes, presentations and other links on the CDC website. There is nothing secret about these meetings or what happens in them.

How does ACIP determine the vaccine schedule?

ACIP meets three times a year to review current research and data for each vaccine. The recommendations are reviewed and modified regularly to incorporate new data and new information on new vaccine formulations. The schedule is chosen to provide maximum protection, as early as possible, without complications or interactions between vaccines.

According to the CDC’s ACIP information sheet (found here), ACIP reviews the following information for each vaccine.

  • The safety and effectiveness of the vaccine when given at specific ages. Only vaccines licensed by the FDA are recommended, and vaccine manufacturers must conduct rigorous studies to show that a vaccine is safe and effective at specific ages.
  • The severity of the disease. Vaccines recommended for children prevent diseases that can be serious for them, potentially causing long-term health problems or death.
  • The number of children who get the disease if there is no vaccine. Vaccines that do not provide benefit to many children may not be recommended for all children.
  • How well a vaccine works for children of different ages. The immune response from a vaccine can vary depending on the age when the vaccine is given.

What information does ACIP consider?

ACIP considers many sources of information, including (but not limited to):

  1. Data related to vaccine effectiveness and safety
  2. Clinical trial results
  3. Manufacturer’s labeling
  4. Package insert information
  5. Outbreaks
  6. Vaccine supply issues

To decide when each vaccine should be given, the main factor that ACIP considers is the risk of disease and death from the disease at different ages. The schedule is designed to provide protection against vaccine-preventable diseases at the earliest time possible. Pertussis is particularly dangerous for infants, so vaccination for pertussis is one of the earliest vaccines given (at 2 months of age) and vaccination of pregnant moms between the 27th and 36th week of pregnancy is recommended to provide protection prior to 2 months of age.

ACIP also decides if vaccines required more than one administration for adequate levels of immunity to develop or if any boosters are required to maintain immunity. For example, as Layla wrote in her article on HPV and HPV vaccines, the HPV vaccines requires 2 shots if vaccinations are started before the age of 15, but 3 shots if started after the age of 15.

The schedule and recommendations include contraindications and precautions about who should not get particular vaccines, allergies, certain medical conditions. People who are immunocompromised or have specific allergies cannot safely receive certain vaccinations and ACIP also determines these exceptions. ACIP provides a detailed list of these on the ACIP webpage: Contraindications and Precautions.

Only vaccines that have received FDA approval for safety and efficacy are eligible to be included in the vaccine schedule. Extensive testing for both safety and efficacy of vaccine is required prior to FDA approval.

Where do alternate vaccine schedules come from?

The alternate schedules promoted by Dr. Sears and others are not tested and are completely made up. They are arbitrary, untested, not evaluated by experts and not subject to any scrutiny. It should also be noted that Dr. Sears was recently reprimanded for offering improper vaccine exemptions.

Doctors who promote alternate schedules argue that these alternate schedules convince parents who might not otherwise vaccinate at all to vaccinate. On the other hand, the active promotion of these untested schedules by doctors may lend legitimacy to these alternate schedules that may actually increase the number of parents who don’t follow the recommended schedule. However, there is a little data on whether this is the case. Delaying vaccines and following an alternate schedule means that you are choosing an untested schedule over a tested schedule and exposing your child to unnecessary and preventable risks.

Keeping track of vaccinations

Vaccination records can easily be lost when we move from place to place, or when we change physicians. NutKat Designs donated a free Vaccination Tracker that you can fill out. Note that this document is not a medical record, and will not supplant official documents that may be needed by schools or your workplace.

vaccine tracker
Click the image to download the Vaccination Tracker PDF from NutKat designs.

This article was originally published on September 17th, 2018. It was updated to include the electronic vaccination record.

This post has been edited on June 24, 2019 to clarify that the vaccine schedule is supported by evidence yielded from clinical trials.