<unk> s are vaccines used to prevent<unk> myelitis<unk> . Two types are used: an inactivated<unk> virus given by injection (IPV) and a weakened<unk> virus given by mouth (OPV). The World Health Organization (WHO) recommends all children be fully vaccinated against<unk> . The two vaccines have eliminated<unk>  from most of the world, and reduced the number of cases reported each year from an estimated 350,000 in 1988 to 33 in 2018. The inactivated<unk> s are very safe. Mild redness or pain may occur at the site of injection. Oral<unk> s cause about three cases of vaccine-associated paralytic<unk> myelitis per million doses given. This compares with 5,000 cases per million who are paralysed following a<unk>  infection. Both types of vaccine are generally safe to give during pregnancy and in those who have HIV/AIDS but are otherwise well. However, the emergence of circulating vaccine-derived<unk> virus (cVDPV), a form of the vaccine virus that has reverted to causing<unk> myelitis, has led to the development of novel oral<unk>  type 2 (nOPV2) which aims to make the vaccine safer and thus stop further outbreaks of cVDPV2. The first successful demonstration of a<unk>  was by Hilary Koprowski in 1950, with a live attenuated virus which people drank. The vaccine was not approved for use in the United States, but was used successfully elsewhere. The success of an inactivated (killed)<unk> , developed by Jonas Salk, was announced in 1955. Another attenuated live oral<unk>  was developed by Albert Sabin and came into commercial use in 1961.<unk>  is on the World Health Organization's List of Essential Medicines.
Polio vaccine
Typhus vaccine
MMRV vaccine
MMR vaccine
Rubella vaccine
Hantavirus vaccine
Typhoid vaccine
Measles vaccine