Immunogenicity, safety and efficacy of tetravalent rhesus-human, reassortant rotavirus vaccine in Belém, Brazil.
A tetravalent rhesus-human reassortant rotavirus (RRV-TV) vaccine (4 x 10(4) plaque-forming units/dose) was evaluated for safety, immunogenicity and efficacy in a prospective, randomized, double-blind, placebo-controlled trial involving 540 Brazilian infants. Doses of vaccine or placebo were given at ages 1, 3 and 5 months. No significant differences were noted in the occurrence of diarrhoea or vomiting in vaccine and placebo recipients following each dose. Low-grade fever occurred on days 3-5 in 2-3% of vaccinees after the first dose, but not after the second or third doses of vaccine. An IgA antibody response to rhesus rotavirus (RRV) occurred in 58% of vaccinees and 33% of placebo recipients. Neutralizing antibody responses to individual serotypes did not exceed 20% when measured by fluorescent focus reduction, but exceeded 40% when assayed by plaque reduction neutralization. There were 91 cases of rotavirus diarrhoea among the 3-dose (vaccine or placebo) recipients during two years of follow-up, 36 of them among children given the vaccine. Overall vaccine efficacy was 8% (P = 0.005) against any diarrhoea and 35% (P = 0.03) against any rotavirus diarrhoea. Protection during the first year of follow-up, when G serotype 1 rotavirus predominated, was 57% (P = 0.008), but fell to 12% in the second year. Similar results were obtained when analysis was restricted to episodes in which rotavirus was the only identified pathogen. There was a tendency for enhanced protection by vaccine against illness associated with an average of 6 or more stools per day. These results are sufficiently encouraging to warrant further studies of this vaccine in developing countries using a higher dosage in an attempt to improve its immunogenicity and efficacy.
Linhares
A C
AC
Instituto Evandro Chagas, Para, Brazil.
Gabbay
Y B
YB
Mascarenhas
J D
JD
de Freitas
R B
RB
Oliveira
C S
CS
Bellesi
N
N
Monteiro
T A
TA
Lins-Lainson
Z
Z
Ramos
F L
FL
Valente
S A
SA
D000818:Animals; D000914:Antibodies, Viral / Q000302:isolation & purification; D004311:Double-Blind Method; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007231:Infant, Newborn; D008253:Macaca mulatta; D011446:Prospective Studies; D012401:Rotavirus / Q000145:classification / Q000276:immunology*; D012400:Rotavirus Infections / Q000276:immunology / Q000517:prevention & control*; D012703:Serotyping; D014765:Viral Vaccines / Q000276:immunology / Q000592:standards*
D000914:Antibodies, Viral; D014765:Viral Vaccines