Making Vaccines: Licensure, Recommendations and Requirements


Licensure, the first of three processes, involves gaining approval from the Food and Drug Administration (FDA). As a result, it is the longest of these processes. It can take years, even decades, before pharmaceutical companies can actually start providing the vaccine. For example, the varicella vaccine took about 11 years to be licensed by the FDA. The speed with which COVID-19 vaccines were made was a direct result of the global public health emergency. The additional resources removed the financial risk typically associated with vaccine development, thereby allowing for the timeline to be shortened by completing several stages in parallel. Unfortunately, some people were incorrectly left with the impression that the speed was the result of steps being skipped, which was not the case.

Vaccines are usually made by first showing that they are safe and effective in experimental animals. Once this is established, the vaccine becomes an Investigational New Drug (IND) and the company is given an IND license to further study the safety and effectiveness of the vaccine in adults, and eventually, children. Again, these trials typically take years, giving companies ample time to provide the FDA with proof of long-term safety and effectiveness.

Read more about pre-licensure studies »


The "recommendation" process begins only after the FDA licenses a vaccine. Doctors don't just decide to start giving the vaccine on their own. They seek the recommendations of the Advisory Committee on Immunization Practices (ACIP), which advises the Centers for Disease Control and Prevention (CDC), the Committee on Infectious Diseases of the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP), among others.

While the FDA licensure process involves determining the risks versus the benefits of a particular vaccine, the recommendation process considers the costs versus the benefits. Here's the distinction:

  • The FDA examines vaccine safety by considering whether there are any risks (negative effects) associated with the vaccine. They ask: "Do these risks outweigh the benefits of the vaccine or vice versa?"
  • In addition to considering the risks and benefits of a vaccine, the ACIP, AAP, AAFP and other groups of professionals, also examine the costs associated with immunizing all or just a segment of the population. For instance, with the chickenpox (varicella) vaccine: What is the cost of immunizing children compared with the potential savings in medical and non-medical costs from immunizing them? (An example of non-medical costs would be money lost by parents who miss work taking care of their child with chickenpox.)
  • Another part of the recommendation process is determining which groups of people within the population would benefit from the vaccine, and on what schedule the vaccine should be given. These decisions are made based on data previously presented to the FDA.

To distinguish between routine and non-routine recommendations, categories have been established:

  • Category A recommendations should be used by everyone within a particular group.
  • Category B recommendations indicate that a vaccine can be used, but it is not routinely recommended for the population.

The important thing to remember about these categories is that they are developed based on societal factors. A parent deciding about vaccines may come to a different conclusion. Category B vaccines are safe and effective, and the cost is typically covered by insurers and government programs, so a parent might see it as an opportunity to further protect their child from a particularly fatal disease.

This conversation has become relevant for parents of teens as a vaccine that protects against meningococcal type B has been given a category B recommendation.

Watch a video in which Dr. Paul Offit describes the differences between the types of recommendations.


Just because a vaccine is recommended for use doesn't mean that it is required for use. State legislatures and health departments determine whether a vaccine is required. They examine the practicality of requiring it for every child within the state. Factored into this equation is whether a local or state government can afford to pay for the vaccines of children whose parents can't afford it.

From a parent's perspective, vaccine requirements shouldn't matter. If a vaccine is considered to be safe and effective by the FDA, and useful for children by groups like the ACIP, AAP and AAFP, then the vaccine is of value and should be given. Local healthcare budgets, although they determine whether a vaccine is to be required for school entry, have little to do with whether a vaccine is safe, effective and useful.

Hear Dr. Offit explain how vaccines are tested by watching this short video, part of the Talking About Vaccines with Dr. Paul Offit video series.

Reviewed by Paul A. Offit, MD on January 09, 2024

Materials in this section are updated as new information and vaccines become available. The Vaccine Education Center staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family's personal health. You should not use it to replace any relationship with a physician or other qualified healthcare professional. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult your physician or, in serious cases, seek immediate assistance from emergency personnel.