History of vaccine development

Although inoculationInoculationThe practice of intentionally exposing someone to matter from smallpox pustules in order to initiate a mild, protective response to the disease. against smallpox was practiced over 2000 years ago in China and India, a British physician, Edward Jenner, is generally credited with ushering in the modern concept of vaccination. In 1796 he used matter from cowpox pustules to inoculate patients successfully against smallpox, which is caused by a related virusVirusAn ultramicroscopic infectious agent that consists of genetic material surrounded by a protein coat. A virus can replicate themselves only within cells of living hosts..

By 1900, there were two human virus vaccines, against smallpox and rabiesRabiesA potentially fatal viral infection spread through the bite of certain warm-blooded animals. It attacks the central nervous system and, if left untreated, is highly fatal in animals., and three bacterial vaccines against typhoidTyphoid (typhoid fever)A serious disease caused by a bacteria called Salmonella Typhi. Typhoid causes a high fever, weakness, stomach pains, headache, loss of appetite, and sometimes a rash. If it is not treated, it can kill up to 30% of people who get it. There are different vaccines to prevent typhoid: inactivated vaccines that require injection, and live attenuated vaccines that are taken orally (by mouth)., choleraCholeraAn acute infectious disease of the small intestine, caused by the bacterium Vibrio cholerae and characterized by profuse watery diarrhea, vomiting, muscle cramps, severe dehydration, and depletion of electrolytes., and plaguePlagueA serious, potentially life-threatening infectious disease that is usually transmitted to humans by the bites of rodent fleas. It was one of the scourges of early human history..

A worldwide case detection and vaccination programme against smallpox gathered pace and, in 1979, the World Health Assembly officially declared smallpox eradicated — a feat that remains one of history's greatest public health triumphs.

During the 20th century, other vaccines that protect against once commonly fatal infections such as pertussisPertussis (also known as whooping cough)An infectious bacterial disease caused by Bordetella pertussis that produces violent, spasmodic coughing; also called whooping cough., diphtheriaDiphtheriaA disease caused by toxigenic strains of Corynebacterium diphtheriae. Often marked by the formation of a false membrane in the throat, diphtheria is a serious vaccine-preventable disease that can cause death in unvaccinated children., tetanusTetanusA disease caused primarily by toxigenic C. tetani. The rare but often fatal disease affects the central nervous system by causing painful muscular contractions., polio, measlesMeaslesA contagious viral disease marked by fever, the eruption of red circular spots on the skin that can be deadly to young and weakened individuals., rubellaRubella (German measles)A viral infection that is usually milder than measles but can cause serious damage or death to a fetus when a pregnant woman is infected., and several other communicable diseases were developed. As these vaccines became available, high-income industrial nations began recommending routine vaccination of their children. There are now over 20 vaccine-preventable diseases.

Based on the emerging success of the smallpox programme, in 1974, the World Health Organization (WHO) launched the Expanded Programme on Immunization (EPI)⁸¹. The initial EPI goals were to ensure that every child received protection against six childhood diseases (i.e. tuberculosisTuberculosis (TB) A disease caused by the bacterium Mycobacterium tuberculosis. The bacteria usually attack the lungs. But, TB bacteria can attack any part of the body such as the kidney, spine, and brain. If not treated properly, TB disease can be fatal., polio, diphtheria, pertussis, tetanus and measles) by the time they were one year of age and to give tetanus toxoid vaccinationsTetanus toxoid (TT) vaccine A preparation of tetanus toxoid used to immunize against tetanus. When given to women of childbearing age, vaccines that contain tetanus toxoid (TT or Td) not only protect women against tetanus, but also prevent neonatal tetanus in their newborn infants. to women to protect them and their newborns against tetanus.

Since then, new vaccines have become available. Some of them, such as hepatitis BHepatitis B A viral infection of the liver that is transmitted through contact with blood or other body fluids that are infected with the hepatitis B virus. Some infections, especially those acquired in infancy, can become chronic and result in cirrhosis and primary liver cancer in adulthood., rotavirusRotavirus A group of viruses that cause diarrhea (rotaviral gastroenteritis) in children., Haemophilus influenzae type b (Hib)Haemophilus influenzae type b (Hib) Bacteria that can cause serious invasive illnesses, such as pneumonia and meningitis; most common in children and persons who are immune compromised (less able to fight off infections). Hib is one of six types of bacteria that are major causes of bacterial meningitis in unimmunized infants. and pneumococcal vaccines, are recommended by the WHO for global use. Others, such as yellow feverYellow fever An infectious viral tropical disease transmitted by mosquitoes and characterized by high fever, jaundice, and gastrointestinal bleeding. vaccine, are recommended in countries where disease burden data indicate they should be used.

By 1990, vaccination was protecting over 80% of the world's children from the six main EPI diseases, and other new vaccines are continually being added to the EPI programmes in many countries.

In 1999, the Global Alliance for Vaccines and Immunization (GAVI) was created to extend the reach of the EPI and to help the poorest countries introduce new and under-used life-saving vaccines into their national programmes.

Although around 24 million infants are still not receiving the full complement of EPI vaccines in the first year of life, the success of the EPI can be judged by the reduction in worldwide cases of measles and poliomyelitis (see graphics). These two diseases are among several (including neonatal tetanus) targeted by the WHO for elimination through vaccination.