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When the current formulation of IPV is used, 90% or more of individuals develop protective antibodies to all three serotypes of polio virus after two doses of inactivated polio vaccine (IPV), and at least 99% are immune to polio 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.By 1958, the National Institutes of Health had determined that OPV produced using the Sabin strains were the safest.
Recent local opposition to vaccination campaigns have evolved due to lack of adequate information, The disease has since resurged in Nigeria and in several other African nations without necessary information, which epidemiologists believe is due to refusals by certain local populations to allow their children to receive the polio vaccine.
The Salk vaccine, IPV, is based on three wild, virulent reference strains, Mahoney (type 1 poliovirus), MEF-1 (type 2 poliovirus), and Saukett (type 3 poliovirus), grown in a type of monkey kidney tissue culture (Vero cell line), which are then inactivated with formalin.
Later analysis suggested that vaccines produced by the former Soviet bloc countries until 1980, and used in the USSR, China, Japan, and several African countries, may have been contaminated, meaning hundreds of millions more may have been exposed to SV40.
In 1998, the National Cancer Institute undertook a large study, using cancer case information from the institute's SEER database.
OPV produces excellent immunity in the intestine, the primary site of wild poliovirus entry, which helps prevent infection with wild virus in areas where the virus is endemic.
The live virus used in the vaccine can rarely shed in the stool and can rarely spread to others within a community.Large-scale clinical trials performed in the Soviet Union in late 1950s to early 1960s by Mikhail Chumakov and his colleagues demonstrated safety and high efficacy of the vaccine.Fifty-seven nucleotide substitutions distinguish the attenuated Sabin 1 strain from its virulent parent (the Mahoney serotype), two nucleotide substitutions attenuate the Sabin 2 strain, and 10 substitutions are involved in attenuating the Sabin 3 strain.Oral polio vaccines were developed by several groups, one of which was led by Albert Sabin. In 1958, the National Institutes of Health created a special committee on live polio vaccines.The various vaccines were carefully evaluated for their ability to induce immunity to polio, while retaining a low incidence of neuropathogenicity in monkeys.The question of whether SV40 causes cancer in humans remains controversial, however, and the development of improved assays for detection of SV40 in human tissues will be needed to resolve the controversy.During the race to develop an oral polio vaccine, several large-scale human trials were undertaken.In Africa, the vaccines were administered to roughly one million people in the Belgian territories (now the Democratic Republic of the Congo, Rwanda, and Burundi).and unfounded accusations in the 1990s arose that the vaccine had created the conditions necessary for transmission of simian immunodeficiency virus from chimpanzees to humans, causing HIV/AIDS.One dose of OPV produces immunity to all three poliovirus serotypes in roughly 50% of recipients.Three doses of live-attenuated OPV produce protective antibodies to all three poliovirus types in more than 95% of recipients.