Vaccines against cholera
Friday, October 5, 2007
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's first live vaccine against cholera, was developed in 1885, the year in which Clua Jaime Ferrán and make the first trials for a vaccine against cholera. To this day have been investigated, tested and eliminated many vaccines for cholera, with all possible routes of administration and all possible forms of production. In the case of the vibrios injection with attenuated, inactivated, polysaccharide and tetanus. And in the case of oral vibrios also inactivated toxoids and also genetically attenuated and GMOs (genetically modified organisms). It was in mid-1980 when made the first clinical trials with two oral cholera vaccines and inactivated. Within
oral attenuated vaccines can highlight those obtained from attenuated Salmonella typhi (Ty21a) expressing the O antigen of V. cholerae Inaba has resulted only slightly immunogenic in adult volunteers with a low efficiency (25%) against infection by V. cholerae wild. Were also tested deletion mutants of V. cholerae O1, among which we highlight the first generation as the JBK 70 A - the CVD 101A - B - and 395N1. And among the second generation we 104hlyA CVD - CVD 105 and CVD 103.
Other vaccines have been tested are: cell vaccine-subunit B, which is a combination of vibrios purified inactivated and subunit B, with protection of approximately 67% and requires multiple doses. And polysaccharide conjugate vaccines have been tested in animals that show an increase in serum antibody titer, but not secretory antibodies and there is only preliminary safety data in adults.
At present and in the search for a vaccine effective, safe and cost arises against cholera vaccine CVD 103-HgR. This vaccine is marketed in Switzerland and Argentina in 1994, Peru in 1995, Canada in 1996 and Philippines in 1997. In all la indicación es para la inmunización de adultos y niños ³ 2 años frente a la enfermedad causada por V. Cholerae. Esta vacuna cumple los requisitos planteados por la Directiva del Consejo 90/220/EEC (23 Abril 1990) sobre liberación deliberada al medio ambiente de Organismos Modificados Genéticamente.
La composición cualitativa y cuantitativa de la vacuna es la siguiente: mínimo 2x10 gérmenes vivos de la cepa atenuada de Vibrio cholerae CVD 103 HgR en forma liofilizada; llevando como excipiente 21,4 mg de sacarosa, 0,6 gramos de lactosa, aspartam y sorbitol, y como tampón 2,65 gramos de bicarbonato sódico y 1,65 gramos de ácido ascórbico y 0,2 gramos de lactosa. Todo ello va presentado Double-bag with a single dose of buffer and once with the vaccine.
In clinical trials has been proven safe, with few gastrointestinal adverse reactions, but with equal incidence in the placebo group than in the vaccinated.
regard to their immunogenicity has been found a good response with the appearance of antibodies against serotype Inaba vibriocidal both American adults and children 2-9 years old Chilean, have been observed seroconversion rates in more than 90% of adults against serotype Inaba and 75% approximately compared to Ogawa, being 50-75% in children.
In clinical trials to assess effectiveness from challenge studies in volunteers has been shown that a single dose of CV103 or CVD 103-HgR has a high protection of nearly 100%, no differences were found in the vibriocidal antibody response between the groups receiving one or two doses . In these same studies have found complete protection with both CVD 103 and CVD 103-HgR, compared with moderate and severe diarrhea.
also are particularly important clinical trials in areas with endemic cholera. In fact studies have been conducted large-scale field in countries like Indonesia to determine the efficacy of a single dose of CVD 103-HgR to protect against cholera in a population naturally exposed to infection.
Therefore, and upon completion of all appropriate clinical research can be said that this is a safe and effective vaccine against cholera, especially in developed countries. The vaccine is effective against both classical and El Tor biotypes.
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