Rotavirus vaccines and vaccination in Latin America

Abstract

Worldwide, rotaviruses account for more than 125 million cases of infantile gastroenteritis and nearly 1 million deaths per year, mainly in developing countries. Rather than other control measures, vaccination is most likely to have a major impact on rotavirus disease incidence. The peak incidence of rotavirus diarrhea occurs between 6 and 24 months of age. In developing countries, however, cases are not uncommon among children younger than 6 months. G serotypes 1 to 4 are responsible for most disease, but there are indications that in Brazil that G type 5 is of emerging epidemiological importance. Both homotypic and heterotypic responses are elicited during natural rotavirus infection, and the immunological response at the intestinal mucosal surface is probably the more consistent predictor of clinical immunity. With the primary objective of protecting children against life-threatening dehydrating diarrhea, many approaches to rotavirus vaccine development have been attempted. One vaccine, the tetravalent rhesus-human reassortant rotavirus vaccine (RRV-TV), was given licensing approval in the United States of America, introduced to the market, and later withdrawn. A number of studies have found better efficacy of RRV-TV in developed countries than in developing ones. Field trials with a 4 x 10(4) plaque-forming units (PFU) preparation of RRV-TV have been carried out in two countries in Latin America, Brazil and Peru. Those trials yielded protective efficacy rates against all rotavirus diarrhea ranging from 18% to 35%. Data from a large catchment trial in Venezuela with a higher RRV-TV dose, of 4 x 10(5) PFU/dose, indicated an efficacy rate of 48% against all rotavirus diarrhea and 88% against severe rotavirus diarrhea. It appears that breast-feeding does not compromise the efficacy of RRV-TV if three doses of the vaccine are administered. Similarly, possible interference of oral poliovirus vaccine with the "take" of the rotavirus vaccine can be overcome by giving three doses of the rotavirus vaccine or by using a higher-titer formulation of it. Wild enteroviruses, however, may cause primary rotavirus vaccine failure in developing countries. Studies in Peru with RRV-TV have shown a trend towards higher vaccine efficacy rates against "pure" (rotavirus-only) diarrheal episodes. Economic analyses made in the United States indicate that a vaccine that costs less than US$ 9 per dose would lead to a net savings in medical costs. To date, however, cost-benefit studies have not been done in developing countries. In the future, it is possible that some Latin American countries might adapt their polio production facilities to the preparation of rotavirus vaccines for human use. A year after RRV-TV was licensed for vaccination of infants in the United States, the occurrence of intussusception as an adverse event led to the vaccine's withdrawal from the market. The implications of that action, particularly for Latin America, will be addressed in this article, including the need to explore alternative rotavirus candidate vacci...

Diarréia por rotavírus em crianças desnutridas hospitalizadas no Instituto Materno Infantil Prof. Fernando Figueira, IMIP

“…17 A maioria das investigações conduzidas na América latina, em crianças abaixo de cinco anos de idade, em nível hospitalar ou ambulatorial, aponta para uma ampla variação nas taxas de freqüência, podendo-se citar: Argentina 12,9 a 34%; Brasil 13 a 40%; Chile 11,4 a 40%; Costa Rica 45,3 a 60% e Venezuela 30 a 50%. 18 No Brasil, vários estudos foram realizados, abrangendo as diferentes regiões do país, com base nos quais se determinaram múltiplas taxas relativas à freqüência das diarréias por rotavírus entre crianças com idades inferiores a seis anos. O contingente sob investigação era representado em sua quase totalidade por demanda ambulatorial ou hospitalar.…”

Epidemiologia das infecções por rotavírus no Brasil e os desafios para o seu controle

“…Prevalece amplo consenso, atualmente, de que o efetivo controle das gastroenterites por rotavírus se condiciona ao advento de uma vacina eficaz para uso corrente ao longo do primeiro semestre de vida (Bresee et al, 1999;Linhares & Bresee, submetido). Tal asserção se fundamenta na singularidade que permeia a epide-Cad.…”

“…Saúde Pública, Rio de Janeiro, 16(3): 629-646, jul-set, 2000 miologia das infecções por esses vírus, evidenciada pelo fato de as taxas de incidência da doença nos países desenvolvidos e naqueles em desenvolvimento serem comparáveis. Deduz-se, por conseguinte, que eventuais intervenções na esfera da saúde pública, como o acesso amplo à água potável e a implementação de medidas visando ao saneamento bási-co, resultarão em impacto inexpressivo no que concerne à morbidade associada às diarréias por rotavírus (Bresee et al, 1999;Linhares & Bresee, submetido).…”

“…As primeiras investigações sobre gastroenterites por rotavírus na América Latina remontam a meados da década de 70, poucos anos após a descoberta desse enteropatógeno por Bishop et al (1973), ressaltando-se o caráter pioneiro dos estudos conduzidos à época no Brasil (Linhares et al, 1977;Linhares & Bresee, submetido). Ao longo de duas décadas, múlti-plos aspectos da infecção por esses vírus têm sido objeto de estudo em âmbito nacional, integrando um espectro que abrange desde os primeiros achados à microscopia eletrônica até a corrente caracterização molecular das cepas circulantes e os ensaios de campo com vacinas experimentais (Leite et al, 1996;Linhares, 1997;.…”

G and P rotavirus genotypes in stool samples from children in Teresina, State of Piauí

“…Worldwide, rotaviruses account for more than 125 million cases of child gastroenteritis and nearly one million deaths per year, mainly in developing countries 24 .…”