A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.

Vaccines can be prophylactic (example: to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine).

The term vaccine derives from Edward Jenner's 1796 use of cow pox (Latin variola vaccinia, adapted from the Latin vaccīn-us, from vacca, cow), to inoculate humans, providing them protection against smallpox.

Vaccines do not guarantee complete protection from a disease. Sometimes, this is because the host's immune system simply does not respond adequately or at all. This may be due to a lowered immunity in general (diabetes, steroid use, HIV infection, age) or because the host's immune system does not have a B cell capable of generating antibodies to that antigen.

Piers Stefan Pughe-Morgan (born Piers Stefan O'Meara; 30 March 1965), known professionally as Piers Morgan, is a British journalist and television presenter. He is editorial director of First News, a national newspaper for children.

Morgan branched into television mainly as a presenter, but has become best known as a judge or contestant in reality television programmes. In the UK, he was a judge on Britain's Got Talent. Morgan is best known in the United States as a judge on the show America's Got Talent, and as the winner of The Celebrity Apprentice. On 17 January 2011, he began hosting Piers Morgan Tonight for CNN in the timeslot previously occupied by Larry King Live after the retirement of host Larry King.

Morgan has authored eight books, including three volumes of memoirs.

Piers Morgan was born on 30 March 1965, in Guildford, Surrey, England, to Eamon Vincent O'Meara, a dentist, of Dorking, Surrey, and Gabrielle Georgina Sybille (née Oliver). His father died when he was one year old; his mother subsequently remarried. He has three older siblings. His ancestry includes Irish, Portuguese, Scottish, and English. Morgan was raised Catholic. Named Piers Stefan Pughe-Morgan by his stepfather, Morgan attended an independent school called Cumnor House from the ages of seven to thirteen, and then Chailey School, a comprehensive secondary school in Chailey, near Lewes, East Sussex, followed by Lewes Priory School for VI form. Morgan studied Journalism at Harlow College. After a brief career at Lloyds of London, he joined the Surrey and South London Newspaper Group in 1985, where he worked as a reporter on the South London News, and the Streatham and Tooting News. Morgan was recruited (he says headhunted by editor Kelvin MacKenzie) to join The Sun newspaper, specifically to work on the Bizarre column.

Seth Franklin Berkley, M.D. (born in 1956 in New York, NY) is a medical epidemiologist by training. He is the CEO of the GAVI Alliance and a global advocate on the power of vaccines. He is also the founder and former President and CEO of the International AIDS Vaccine Initiative (IAVI).. Graduated McBurney School, New York, 1974, he received a Bachelor of Science and medical degrees from Brown University, and trained in internal medicine at Harvard University. Berkley has been featured on the cover of Newsweek and recognized by Wired Magazine as among "The Wired 25" - a salute to dreamers, inventors, mavericks and leaders - as well as by TIME magazine as one of the "100 Most Influential People in the World" in 2009. In 2010, Fortune magazine named Berkley as one of its "Global Forum Visionaries." Speaking at the TED 2010 conference, Dr. Berkley explains how innovative vaccine design and production technologies are bringing us closer to controlling global health threats like flu and HIV.

Andrew Jeremy Wakefield (born 1957) is a British former surgeon and medical researcher, known as an advocate for the discredited claim that there is a link between the measles, mumps and rubella (MMR) vaccine, autism and bowel disease, and for his fraudulent 1998 research paper in support of that claim.

Four years after the publication of the paper, other researchers' results had still failed to reproduce Wakefield's findings or confirm his hypothesis of a relation between childhood gastrointestinal disorders and autism. A 2004 investigation by Sunday Times reporter Brian Deer identified undisclosed financial conflicts of interest on Wakefield's part, and most of his coauthors then withdrew their support for the study's interpretations. The British General Medical Council (GMC) conducted an inquiry into allegations of misconduct against Wakefield and two former colleagues. The investigation centred on Deer's numerous findings, including one that autistic children were subjected to unnecessary invasive medical procedures, such as colonoscopy and lumbar puncture, and that Wakefield acted without the required ethical approval from an institutional review board.