This 1963 poster featured CDC's national symbol of public health, the "Wellbee", encouraging the public to receive an oral<unk> . Interruption of person-to-person transmission of the virus by<unk> tion is important in global<unk>  eradication, since no long-term carrier state exists for<unk> virus in individuals with normal immune function,<unk>  viruses have no nonprimate reservoir in nature, and survival of the virus in the environment for an extended period of time appears to be remote. There are two types of<unk> : inactivated<unk>  (IPV) and oral<unk>  (OPV). Inactivated When the IPV (injection) is used, 90% or more of individuals develop protective antibodies to all three serotypes of<unk>  virus after two doses of inactivated<unk>  (IPV), and at least 99% are immune to<unk>  virus following three doses. The duration of immunity induced by IPV is not known with certainty, although a complete series is thought to provide protection for many years. IPV replaced the oral<unk>  in many developed countries in the 1990s mainly due to the (small) risk of<unk> -derived<unk>  in the oral<unk> . Attenuated Oral<unk> s were easier to administer than IPV, as it eliminated the need for sterile syringes and therefore was more suitable for mass<unk> tion campaigns. OPV also provided longer-lasting immunity than the Salk<unk> , as it provides both humoral immunity and cell-mediated immunity. One dose of OPV produces immunity to all three<unk> virus serotypes in roughly 50% of recipients. Three doses of live-attenuated OPV produce protective antibodies to all three<unk> virus types in more than 95% of recipients. OPV produces excellent immunity in the intestine, the primary site of wild<unk> virus entry, which helps prevent infection with wild virus in areas where the virus is endemic. The live virus used in the<unk>  can rarely shed in the stool and can rarely spread to others within a community. The live virus also has stringent requirements for transport and storage, which are a problem in some hot or remote areas. As with other live-virus<unk> s, immunity initiated by OPV is probably lifelong. The trivalent (against wild types 1, 2, and 3) OPV has been used to nearly eradicate<unk>  infection worldwide. Led by the Global<unk>  Eradication Initiative, 155 countries switched to use the bivalent (against wild types 1 and 3) between 17 April and 1 May 2016. The bivalent OPV is more effective against types 1 and 3, but does not cover type 2. The United States as of 2017 continues to recommend the use of a trivalent version, but a fully inactivated version. The switch to the bivalent<unk>  and associated missing immunity against type 2 strains, among other factors, led to outbreaks of circulating<unk> -derived<unk> virus type 2(cVDPV2), which increased from 2 cases in 2016 to 1037 cases in 2020. As a response, a novel oral<unk>  type 2 (nOPV2) was developed with the aim to provide a safer form of<unk> tion against type 2 strains with less risk of reverting to infectious<unk> . Schedule Share of one-year-olds<unk> ted against<unk>  in 2015 In countries with endemic<unk>  or where the risk of imported cases is high, the WHO recommends OPV<unk>  at birth followed by a primary series of three OPV doses and at least one IPV dose starting at 6 weeks of age, with a minimum of 4 weeks between OPV doses. In countries with >90% immunization coverage and low risk of importation, the WHO recommends one or two IPV doses starting at 2 months of age followed by at least two OPV doses, with the doses separated by 4–8 weeks depending on the risk of exposure. In countries with the highest levels of coverage and the lowest risks of importation and transmission, the WHO recommends a primary series of three IPV injections, with a booster dose after an interval of six months or more if the first dose was administered before 2 months of age.
Polio vaccine
Typhus vaccine
MMRV vaccine
MMR vaccine
Rubella vaccine
Hantavirus vaccine
Typhoid vaccine
Measles vaccine