Measles Vaccine Clinical Trial
Official title:
Immunity Duration Study Eight Years After Vaccination of Children 12 to 23 Months With the Triple Viral Vaccine (Measles, Mumps and Rubella)
Several studies on the duration of immunity after the vaccine try to explain the cause of susceptibility to the measles virus even after the administration of 2 doses of the viral triple vaccine, based not only on the finding of low vaccine coverage. In the recent measles epidemic that occurred in Brazil, beginning in 2018, we verified the predominance of the D8 genotype, with different strains. The detection of these strains is an important molecular marker to define different introductions of the same genotype, in the same geographic area, enabling better knowledge and discussion of the control strategies used. Some news circulated in the press about a possible failure of the vaccine to protect the vaccinated population against this D8 genotype. Regarding the mumps and rubella components, analyzes of the duration of immunity will be carried out for these 2 components, in addition to measles, since the children received in 2012 the triple viral vaccine, and there are data in the literature on the drop in antibodies to mumps, over the years. For rubella, Brazil received the rubella virus elimination certificate, and the results of duration of immunity from this study, may collaborate to know the profile of duration of immunity to rubella, in this cohort vaccinated in 2012, and who is living in a period without circulation of the wild virus.
In this project, the investigators propose: - Evaluate the proportion of seropositive people for measles, mumps and rubella, in relation to the doses of the triple viral vaccine administered, and recorded on the vaccination card, and correlate with the time elapsed since the last dose, of the children vaccinated at 12 months of age, in a study carried out in 2012, and which in 2020 will be 8 or 9 years old; - Compare antibody titers in vaccinees, at 12 - 23 months of age, in 2012, in the study that compared the mono x multidose presentations of the triple viral vaccine, evaluating the serums collected at that time, in the post-vaccination post-vaccination samples (one dose from triple viral), and stored in the biorepository, and the recent sera, from samples that will be collected in 2020, 8 years later, against the vaccine virus and the wild virus, strain D8; - Evaluate cellular immunity to measles, rubella and mumps components, in samples collected in 2020. Children who participated in the study in 2012 received 1 dose of the triple viral vaccine at 12 - 23 months of age. After serology, IgG, using the immunoenzymatic assay (ELISA) method, children who had not presented seroconversion to any of the components of the triple viral vaccine received another dose of the vaccine. In 2012, the PNI recommended a 2nd dose of the triple viral vaccine at 4 years of age. Probably, this year, 2020, children who are included in the study will be able to register at least 2 doses of the triple viral vaccine, at 12 months as a participant in the 2012 study, and a 2nd dose of the triple viral vaccine, if they were vaccinated. at the age of 4 as recommended by the PNI. In addition, these children may have received more doses of triple viral vaccine, if they were vaccinated in a vaccination campaign, blocking vaccination, because of the measles outbreak in Rio de Janeiro. ;
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