RESUMO
OBJECTIVE: We evaluated the seroprevalence for measles, mumps, and rubella in school-age children (6-12 years old) before and after the administration of three triple combined viral vaccines. METHODS: In two municipal schools of Rio Grande do Sul, Brazil, 692 blood samples were collected before vaccination and 636 samples 21 to 30 days after vaccination during 1996. IgG antibody seropositivity was investigated by enzyme-linked immunosorbent assay (measles and mumps with Enzygnost [Behring, Marburg, Germany]; rubella with Rubenostika [Organon Teknica, Boxtel, the Netherlands]). The vaccines compared were: A: E-Zagreb, L-Zagreb, and Wistar RA 27/3 (Tresivac); B: Moraten, J-Lynn, and Wistar RA 27/3 (M-M-R II); and C: Schwarz, Urabe AM-9, and Wistar RA 27/3 (Trimovax). RESULTS: Before vaccination, 79.2% [95% confidence interval (CI)=76.0%-82.2%] of the samples were positive for measles, 69.4% (95% CI=65.8%-72.8%) for mumps, and 55.4% (95% CI=51.6%-59.2%) for rubella. After vaccination with the A, B, and C vaccines, seropositivity was 100.0%, 99.5%, and 100.0%, respectively for measles; 99.5%, 94.5%, and 92.0% for mumps; and 92.6%, 91.3%, and 88.6% for rubella. CONCLUSIONS: About one-fifth (20.8%) of the schoolchildren who could have been vaccinated against measles at age 9 months had levels of antibodies insufficient for protection. In the sample of schoolchildren without previous vaccination against mumps and rubella, high proportions of susceptible levels were found. All vaccines were immunogenic, but vaccine A yielded a seroconversion rate of 99.5% for the mumps component, which was significantly higher than the other two vaccines (P<0.01).
Assuntos
Anticorpos Antivirais/sangue , Vacina contra Sarampo-Caxumba-Rubéola/imunologia , Brasil , Criança , Método Duplo-Cego , Feminino , Humanos , Masculino , Sarampo/sangue , Sarampo/epidemiologia , Sarampo/prevenção & controle , Caxumba/sangue , Caxumba/epidemiologia , Caxumba/prevenção & controle , Rubéola (Sarampo Alemão)/sangue , Rubéola (Sarampo Alemão)/epidemiologia , Rubéola (Sarampo Alemão)/prevenção & controle , Estudos Soroepidemiológicos , Fatores de TempoRESUMO
OBJECTIVE: To compare the incidence of adverse events following the administration of three commercially available measles-mumps-rubella (MMR) combination vaccines. METHODS: A randomized double-blind clinical trial was performed in 1996 that involved a total of 10 142 students 6-12 years of age in the state of Rio Grande do Sul, in Brazil. An MMR vaccine containing the Edmonston-Zagreb, Leningrad-Zagreb, and RA 27/3 strains ("vaccine A") was administered to 2 226 students (21.9% of the total); an MMR vaccine with the Moraten, Jeryl Lynn, and Wistar 27/3 strains ("vaccine B") was administered to 2 216 children (21.8%); and an MMR vaccine containing the Schwartz, Urabe AM-9, and Wistar 27/3 strains ("vaccine C") was given to 2 179 students (21.5%). A control group of 3 521 students (34.7%) was not vaccinated. Both the vaccinated subjects and the control subjects were followed daily for 30 days to detect any clinical manifestations. RESULTS: Adverse events were more frequent in the vaccinated children than in the control group (P < 0.01). In terms of causing parotitis, vaccine A had a relative risk (RR) of 5.72 (95% confidence interval (CI) = 3.11-10.54) when compared with vaccine B, and an RR of 2.33 (95% CI = 1.52-3.58) when compared with vaccine C. Vaccine A was also associated with an increased risk of lymphadenopathy when compared with vaccine B (RR = 3.11; 95% CI = 1.78-5.45) and with vaccine C (RR = 2.22; 95% CI = 1.35-3.66). Vaccine C was associated with an increased risk of parotitis when compared with vaccine B (RR = 2.46; 95% CI = 1.26-4.80). Three cases of aseptic meningitis were detected among the children in the study group, but only one case of vaccine-related aseptic meningitis was identified, among the children receiving vaccine A. CONCLUSIONS: The three MMR vaccines that we studied are associated with different risks of adverse events. We found vaccine A to cause more reactions than the two other vaccines, especially vaccine B. In addition, vaccine A presented both a temporal and a cause-and-effect association with one case of aseptic meningitis. We hope that this study will contribute information that can be used in choosing MMR vaccines with safe and effective strains, especially for mass vaccination strategies.