Passive immunization In 1950, William Hammon at the University of Pittsburgh purified the gamma globulin component of the blood plasma of<unk>  survivors. Hammon proposed the gamma globulin, which contained antibodies to<unk> virus, could be used to halt<unk> virus infection, prevent disease, and reduce the severity of disease in other patients who had contracted<unk> . The results of a large clinical trial were promising; the gamma globulin was shown to be about 80 percent effective in preventing the development of paralytic<unk> myelitis. It was also shown to reduce the severity of the disease in patients who developed<unk> . Due to the limited supply of blood plasma gamma globulin was later deemed impractical for widespread use and the medical community focused on the development of a<unk>  vaccine. Vaccine A child receiving an oral<unk>  vaccine Two types of vaccine are used throughout the world to combat<unk> . Both types induce immunity to<unk> , efficiently blocking person-to-person transmission of wild<unk> virus, thereby protecting both individual vaccine recipients and the wider community (so-called herd immunity). The first candidate<unk>  vaccine, based on one serotype of a live but attenuated (weakened) virus, was developed by the virologist Hilary Koprowski. Koprowski's prototype vaccine was given to an eight-year-old boy on 27 February 1950. Koprowski continued to work on the vaccine throughout the 1950s, leading to large-scale trials in the then Belgian Congo and the vaccination of seven million children in Poland against serotypes PV1 and PV3 between 1958 and 1960. The second<unk>  virus vaccine was developed in 1952 by Jonas Salk at the University of Pittsburgh, and announced to the world on 12 April 1955. The Salk vaccine, or inactivated<unk> virus vaccine, is based on<unk> virus grown in a type of monkey kidney tissue culture (vero cell line), which is chemically inactivated with formalin. After two doses of inactivated<unk> virus vaccine (given by injection), 90 percent or more of individuals develop protective antibody to all three serotypes of<unk> virus, and at least 99 percent are immune to<unk> virus following three doses. Subsequently, Albert Sabin developed another live, oral<unk>  vaccine. It was produced by the repeated passage of the virus through nonhuman cells at subphysiological temperatures. The attenuated<unk> virus in the Sabin vaccine replicates very efficiently in the gut, the primary site of wild<unk> virus infection and replication, but the vaccine strain is unable to replicate efficiently within nervous system tissue. A single dose of Sabin's oral<unk>  vaccine produces immunity to all three<unk> virus serotypes in about 50 percent of recipients. Three doses of live-attenuated oral vaccine produce protective antibody to all three<unk> virus types in more than 95 percent of recipients. Human trials of Sabin's vaccine began in 1957, and in 1958 it was selected, in competition with the live vaccines of Koprowski and other researchers, by the US National Institutes of Health. Licensed in 1962, it rapidly became the only<unk>  vaccine used worldwide. Wild<unk>  vs cVDVP cases (2000–2019) Because the oral<unk>  vaccine is inexpensive, easy to administer, and produces excellent immunity in the intestine (which helps prevent infection with wild virus in areas where it is endemic), it has been the vaccine of choice for controlling<unk> myelitis in many countries. On very rare occasions (about one case per 750,000 vaccine recipients), the attenuated virus in the oral<unk>  vaccine reverts into a form that can paralyze. In 2017, cases caused by vaccine-derived<unk> virus (cVDPV) outnumbered wild<unk> virus cases for the first time, due to wild<unk>  cases hitting record lows. Most industrialized countries have switched to inactivated<unk>  vaccine, which cannot revert, either as the sole vaccine against<unk> myelitis or in combination with oral<unk>  vaccine.
Polio
Sequela
Rubella
Typhidot
Smallpox
Mumps
Tongue disease
Cowpox