Status of New Cholera Vaccines
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چکیده
The prospect of developing an effective cholera vaccine has improved in recent years, with increased understanding of the mucosal immune system that protects against enteric infections and the discovery that volunteers recovering from cholera were substantially protected against reinfection for several years. The ideal vaccine would be cheap, safe, easy to administer, and effective after a single dose, and would protect both nonimmune and immune persons against severe illness for a prolonged period, while possibly reducing the risk of asymptomatic infection. The vaccine would likely be given orally, to optimally stimulate enteric mucosal immunity. Two new oral vaccines-the killed whole cell/B subunit (WC/B) formulation and the live mutant CVD 103 HgR-represent considerable progress toward these goals. A cholera vaccine composed of killed whole bacteria is currently available commercially, but its use has been generally discouraged because it confers only modest and brief protection, does not prevent asymptomatic infection, and has only been tested in endemic settings where naturally acquired immunity was also present, Since two parenteral doses are required and protection develops only after several weeks, mass vaccination during an epidemic is impractical as well as potentially wasteful of resources that could be put into proven control measures. In the face of the current epidemic and in light of the recent development of new types of cholera vaccine, the status of these vaccines and WHO recommendations concerning their use were reviewed in a meeting that took place at PAHO Headquarters in Washington, D.C., on 3-4 May 1991.
منابع مشابه
Technical considerations of cholera vaccines and some results of cholera - El-Tor mass immunization
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