If you are like me, the amount of time that has passed since an event is not closely correlated with your perception of the passage of time. For example, it’s hard for me to believe that:

  • It’s been almost four years since COVID-19 vaccines became available.
  • HPV vaccine has been available in the United States for 15 years, and the 9-valent vaccine has already been used for a decade.
  • In the United States, invasive Haemophilus influenzae type b, which caused horrific disease when I was a resident during the late 1980s, has virtually disappeared (infection rate of .02 per 100,000 people in 2022) thanks to the availability of a safe and effective vaccine since 1985.

Sometimes, it's useful to have these dates at your fingertips, such as when talking to a concerned parent about the “newness” of a vaccine or when explaining changes to vaccine recommendations due to changing epidemiological patterns of disease. For help with these types of timeline-related questions, I recommend several tools.


Immunize.org’s recently redesigned website has a “Vaccine History Timeline” webpage, which was updated in January 2024. To locate the page, go to the “Vaccines & VISs” tab. On the left side, you will find the “Vaccine History Timeline.” While not exhaustive, it shows a lot of the vaccine- and immunization-related events that have occurred since Jenner’s critical discovery related to protection against smallpox using cowpox. If you would like to make an addition to the timeline, send your idea to admin@immunize.org.

Vaccine Education Center at Children’s Hospital of Philadelphia

The Vaccine Education Center at Children’s Hospital of Philadelphia (VEC) offers a “Vaccine History” website section with several useful timeline-related pages:

  • Developments by Year. This webpage, updated in August 2023, outlines the first vaccines and vaccine developments by decade from the late 1940s on. It describes how before 1995, key stakeholders updated the immunization schedule every few years as needed. Then, every year since 1995 the Centers for Disease Control and Prevention (CDC), American Academy of Pediatrics (AAP), and American Academy of Family Physicians (AAFP) endorsed annual childhood and adult immunization schedules. Sections of the page also address adolescent and adult vaccine history.
  • Vaccine Availability Timeline. This webpage, updated in January 2024, is sorted by year and whether vaccines are routine or non-routine. The years listed on this timeline represent when vaccines first became available in the United States.
  • Contagious Diseases in the U.S. from 1888 to 2011. This webpage, reviewed in January 2024, summarizes a 2013 study of the effect of vaccines. The study authors estimated that about 103 million cases of disease had been prevented by vaccination from 1924 to 2011. Of the hypothetical cases, about one-quarter were prevented between 2002 through 2011. About 40% of the cases prevented were diphtheria, which had a high pre-vaccination incidence (237 cases per 100,000 population year). The disease with the most rapid decrease in the number of reported cases was measles (22% decrease each year post-vaccination).
  • Vaccine History: Scientists – In Memoriam. This webpage, updated in January 2024, includes a synopsis of the careers of key leaders in vaccinology who have passed away in recent years. In the 1997 movie, “As Good as It Gets,” Melvin (Jack Nicholson) says to his date, “You make me want to be a better man.” Reading this webpage makes me want to be a better physician and a better person.

Hilleman: A Perilous Quest to Save the World's Children

This website, presented by the VEC, includes historical information and interviews of vaccine scientists. The website is subdivided into four sections:

  • The Film – This section includes information about how to view the award-winning documentary, HILLEMAN: A Perilous Quest to Save the World’s Children.
  • About Dr. Hilleman – This section offers a brief history and photos highlighting Dr. Hilleman’s life and accomplishments.
  • News and Events – This section features stories from The Hilleman Chronicle, a quarterly electronic newsletter published by the VEC for science and history enthusiasts, as well as other newsworthy items, such as film awards, student essay contest news, and more. The Hilleman Chronicle newsletter was launched in 2023. People can sign up for it here.
  • Resources – The heart of this part of the website is the “Other Scientists Stories” section where you can find the stories of other well-known scientists, such as Anthony Fauci, Samuel Katz, Kizzmekia Corbett and Marion Gruber. In addition to text-based information, many of these stories also feature short films or video clips. Also found in this section is information about the annual Maurice R. Hilleman Student Essay Contest, including winning essays from previous years and links to and information about other VEC programs.

The College of Physicians of Philadelphia

The College of Physicians of Philadelphia offers a website called “History of Vaccines.” This website provides basic information about how vaccines work as well as interesting historical information. Particularly relevant to this article is the “Vaccine Timeline Before Jenner and After COVID-19,” which has two sections, an overview of vaccine history and a timeline. As described in the overview, “The history of vaccines did not begin with Jenner's smallpox vaccine. It will not end with the recent vaccines against the novel coronavirus, which caused the COVID-19 pandemic.”

Whether you are trying to remember a particular date when something related to vaccines happened or if you simply have an interest in vaccine history, you will find these informational resources to be of value.

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.