International journal of epidemiology
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Clinical Trial
Predictors and impact of losses to follow-up in an HIV-1 perinatal transmission cohort in Malawi.
Large simple trials which aim to study therapeutic interventions and epidemiological associations of human immunodeficiency virus (HIV) infection, including perinatal transmission, in Africa may have substantial rates of loss to follow-up. A better understanding of the characteristics and the impact of women and children lost to follow-up is needed. ⋯ Several predictors of loss to follow-up were identified in this large HIV perinatal cohort. Losses to follow-up can impact the observed transmission rate and the risk associations in different studies.
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Comparative Study
Longitudinal study of Plasmodium falciparum infection and immune responses in infants with or without the sickle cell trait.
Individuals may be homozygous (SS) or heterozygous (AS) sickle cell gene carriers or have normal adult haemoglobin (AA). Haemoglobin S could have a protective role against malaria but evidence is sparse and the operating mechanisms are poorly known. ⋯ Sickle cell trait related antimalarial protection varies with age. The role of the modifications of the specific immune response to P. falciparum in explaining the protection of AS children against malaria is discussed.
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Comparative Study
The effect of water fluoridation and social inequalities on dental caries in 5-year-old children.
Many studies have shown that water fluoridation dramatically reduces dental caries, but the effect that water fluoridation has upon reducing dental health inequalities is less clear. The aim of this study is to describe the effect that water fluoridation has upon the association between material deprivation and dental caries experience in 5-year-old children. ⋯ Water fluoridation reduces dental caries experience more in materially deprived wards than in affluent wards and the introduction of water fluoridation would substantially reduce inequalities in dental health.
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Randomized Controlled Trial Comparative Study Clinical Trial
Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy.
Previous studies from Africa have suggested that there is little benefit to be gained from early two-dose measles vaccination schedules. Two-dose schedules have been associated with no improvement in coverage due to immunization of the same individuals on both occasions, low return rate, high refusal rate, low vaccine efficacy, and fear of blunting of the antibody response. Because of the poor results achieved previously with two-dose measles vaccination schedules, we studied patterns of participation, reasons for non-participation, vaccination coverage and relative efficacy of a one-dose versus a two-dose schedule in connection with the implementation of an early two-dose trial in Guinea-Bissau. ⋯ In this study of a two-dose measles immunization schedule at 6 and 9 months of age there was no sign of low participation or poor return rates. The risk of not being vaccinated was lower in the two-dose group than in the one-dose group, and the relative efficacy of a two-dose versus a one-dose schedule was high. Although our results were obtained within a trial where dedicated personnel informed every participant personally about the study, we believe our results indicate that with thorough information about the population it may be possible to achieve a higher coverage with a two-dose measles vaccination schedule than a one-dose schedule. A two-dose schedule may be a feasible way to resolve the problems of low coverage and severe measles infection among infants.