(CNN)Here's a look at information and statistics concerning vaccines in the United States. For vaccines related to coronavirus, see Coronavirus Outbreak Timeline Fast Facts.
Facts
The Centers for Disease Control and Prevention (CDC) provides vaccine recommendations by age, as well as by disease.
For more than 100 years, there has been public discord regarding vaccines based on issues like individual rights, religious freedoms, distrust of government and the effects that vaccines may have on the health of children.
Exemptions to vaccines fall into three general categories: medical, religious and philosophical.
Timeline
1796 - Edward Jenner develops the smallpox vaccine, the world's first successful vaccine.
1855 - Massachusetts mandates that school children are to be vaccinated (only the smallpox vaccine is available at the time).
February 20, 1905 - In Jacobson v. Massachusetts, the US Supreme Court upholds the State's right to compel immunizing against smallpox.
November 13, 1922 - The US Supreme Court denies any constitutional violation in Zucht v. King in which Rosalyn Zucht believes that requiring vaccines violates her right to liberty without due process. The High Court opines that city ordinances that require vaccinations for children to attend school are a "discretion required for the protection of the public health."
1952 - Dr. Jonas Salk and his team develop a vaccine for polio. A nationwide trial leads to the vaccine being declared in 1955 to be safe and effective.
1963 - The first measles vaccine is released. In 2000, the CDC declares the US has achieved measles elimination, defined as "the absence of continuous disease transmission for 12 months or more in a specific geographic area." While the US has maintained measles elimination since, there are occasional outbreaks.
1986 - Congress passes the National Childhood Vaccine Injury Act. This coordinates vaccine activities across several government agencies to monitor vaccine safety, requires vaccine information statements are provided to those receiving vaccines, and creates the National Vaccine Injury Compensation Program to compensate those injured by vaccines on a "no fault" basis.
March 19, 1992 - Rolling Stone publishes an article by Tom Curtis, "The Origin of AIDS," which presents a theory that ties HIV/AIDS to polio vaccines. Curtis writes that in the late 1950s, during a vaccination campaign in Africa, at least 325,000 people were immunized with a contaminated polio vaccine. The article alleges that the vaccine may have been contaminated with a monkey virus and is the cause of the human immunodeficiency virus, later known as HIV/AIDS.
August 10, 1993 - Congress passes the Omnibus Budget Reconciliation Act which creates the Vaccines for Children Program, providing qualified children free vaccines.
December 9, 1993 - Rolling Stone publishes an update to the Curtis article, clarifying that his theory was not fact, and Rolling Stone did not mean to suggest there was any scientific proof to support it, and the magazine regrets any damage caused by the article.
1998 - British researcher Andrew Wakefield and 12 other authors publish a paper stating they had evidence that linked the vaccination for Measles, Mumps and Rubella (MMR) to autism. They claim they discovered the measles virus in the digestive systems of autistic children who were given the measles, mumps and rubella (MMR) vaccine. The publication leads to a widespread increase in the number of parents choosing not to vaccinate their children for fear of its link to autism.
2004 - Co-authors of the Wakefield study begin removing their names from the article when they discover Wakefield had been paid by lawyers representing parents who planned to sue vaccine manufacturers.
May 14, 2004 - The Institute of Medicine releases a report "rejecting a causal relationship between the MMR vaccine and autism."
February 2010 - The Lancet, the British medical journal that published Wakefield's study, officially retracts the article. Britain also revokes Wakefield's medical license.
2011 - Investigative reporter Brian Deer writes a series of articles in the BMJ exposing Wakefield's fraud. The articles state that he used distorted data and falsified medical histories of children that may have led to an unfounded relationship between vaccines and the development of autism.
2011 - The US Public Health Service finds that 63% of parents who refuse and delay vaccines do so for fear their children could have serious side effects.
June 17, 2014 - After analyzing 10 studies, all of which looked at whether there was a link between vaccines and autism and involved a total of over one million children, the University of Sydney publishes a report saying there is no correlation between vaccinations and the development of autism.
February 2015 - Advocacy group Autism Speaks releases a statement, "Over the last two decades, extensive research has asked whether there is any link between childhood vaccinations and autism. The results of this research are clear: Vaccines do not cause autism. We urge that all children be fully vaccinated.
August 23, 2018 - A study published in the American Journal of Public Health finds that Twitter accounts run by automated bots and Russian trolls masqueraded as legitimate users engaging in online vaccine debates. The bots and trolls posted a variety of anti-, pro- and neutral tweets and directly confronted vaccine skeptics, which "legitimize" the vaccine debate, according to the researchers.
October 11, 2018 - Two reports published by the CDC find that vaccine exemption rates and the percentage of unvaccinated children are on the rise.
January 2019 - The World Health Organization names vaccine hesitancy as one of 10 threats to global health in 2019.
September 4, 2019 - Facebook announces that educational pop-up windows will appear on the social media platforms when a user searches for vaccine-related content, visits vaccine-related Facebook groups and pages, or taps a vaccine-related hashtag on Instagram
December 19, 2019 - The US Food and Drug administration announces the approval of a vaccine for the prevention of the Ebola virus for the first time in the United States. The vaccine, Ervebo, was developed by Merck and protects against Ebola virus disease caused by Zaire ebolavirus in people 18 and older.
December 27, 2019 - A study published in the medical journal JAMA Network Open finds that a single dose of the human papillomavirus (HPV) vaccine may be just as effective as two or three doses at preventing cancer-causing HPV infection.
February 3, 2020 - The National Institute of Allergy and Infectious Diseases (NIAID) announces that a clinical trial for an HIV vaccine has been discontinued since the vaccine was not found to prevent infections of human immunodeficiency virus, the virus that causes AIDS.
May 3, 2023 - The US FDA approves, Arexvy, the first vaccine to protect against respiratory syncytial virus or RSV. It is a single shot for adults 60 or older.
