RESUMO
A clinical trial among 137 healthy children, ages 1 to 12 years, was conducted with four different doses (4,350, 870, 435, and 43 plaque-forming units [pfu]) of live Oka/Merck varicella vaccine to evaluate clinical reactions and selected laboratory parameters and to determine the minimum effective dose and induction time of antibody. The vaccine was well tolerated with no significant difference in the rate of reported symptoms by dose. The frequency of varicellalike rash was 3% (4/137); all rashes were mild. Serum aminotransferase values were essentially unchanged after vaccination. Minor variations found in platelet counts after vaccination were not associated with any bleeding, bruising, or clotting. Among initially seronegative children who received doses of 435 pfu or greater, 94% assayed at two weeks and 100% assayed at four or six weeks seroconverted. The geometric mean titers were similar for all four doses at six weeks. IgG and IgA responses were demonstrated with no relation to the vaccine dose.
Assuntos
Vacinas Atenuadas/imunologia , Vacinas Virais/imunologia , Alanina Transaminase/sangue , Anticorpos Antivirais/biossíntese , Aspartato Aminotransferases/sangue , Varicela/etiologia , Vacina contra Varicela , Criança , Pré-Escolar , Feminino , Febre/etiologia , Seguimentos , Herpesvirus Humano 3/imunologia , Humanos , Imunoglobulina A/biossíntese , Imunoglobulina G/biossíntese , Lactente , Masculino , Dor/etiologia , Contagem de Plaquetas , Vacinas Atenuadas/efeitos adversos , Vacinas Virais/efeitos adversosRESUMO
We conducted a double-blind, placebo-controlled efficacy trial of the live attenuated Oka/Merck varicella vaccine among 956 children between the ages of 1 and 14 years, with a negative clinical history of varicella. Of the 914 children who were serologically confirmed to be susceptible to varicella, 468 received vaccine and 446 received placebo. The vaccine produced few clinical reactions and was well tolerated. There was no clinical evidence of viral spread from vaccinated children to sibling controls. Approximately eight weeks after vaccination, 94 per cent of the initially seronegative children who received vaccine had detectable antibody to varicella. During the nine-month surveillance period, 39 clinically diagnosed cases of varicella, 38 of which were confirmed by laboratory tests, occurred among study participants. All 39 cases occurred in placebo recipients; no child who received vaccine contracted varicella. The vaccine was 100 per cent efficacious in preventing varicella in this population of healthy children (P less than 10(-9).
