The British Medical Journal is launching a competition to decided the greatest medical breakthrough.
Present-day medical experts are championing discoveries from the last 166 years.
Michael Worboys, director of the Centre for the History of Science, Technology and Medicine and Wellcome Unit for the History of Medicine, University of Manchester is backing vaccines.
Edward Jenner, a country doctor from Gloucestershire was the first to develop what could be called a vaccine.
Vaccination is used across the world
He noticed that milkmaids who had suffered from cowpox, also known as vaccinia, were also immune to smallpox, which could be deadly.
He carried out a small study where he inoculated people with small amounts of cowpox - and called it a "vaccine".
But it was Louis Pasteur's development of what he dubbed a vaccine against rabies in 1885 - which contained a treated live virus - which grabbed global attention.
He successfully treated two children who had been badly bitten by rabid dogs - which would have previously meant certain death.
His work led to the development of vaccines using inactivated micro-organisms against major killers such as cholera, typhoid fever and the plague.
In the 20th century a raft of vaccines, including those for diphtheria, whooping cough, measles, rubella were developed and given on a mass scale.
In this century, scientists are hoping to develop vaccines against common infections such as staphylococci and pneumococci as well as malaria, HIV and severe acute respiratory syndrome (SARS).
Dr Worboys said vaccines should win the medical milestone award because: "Vaccines have saved hundreds of millions of lives and spared generations the suffering and long term consequences of infections."