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To the GHT statisticians, I need confirmation about the best approach to design an epidemiological study on "causes of rota vaccine failure in children". My programme will vaccinate and follow up a birth cohort of about 170,000 children with rota virus vaccine. In parallel to this implementation work, i am considering designing some research to evaluate potential causes of vaccine failure such as high levels of maternal immunity, levels of IgA in milk, severe malnutrition and HIV/AIDS. Expected vaccine efficacy is about 49.2% and seroconversion rates of about 47.8%. Alpha at 5%, 95% confidence and 80% power. I need some comments/guidance as to the sample size approach. Many thanks, Roma
170,000 children is quite a big sample size... If you are going to use all the children for your research, then sample size should be the least of your worries. However, for proper study design writting you need to do the calculations. You need to provide more information especially relating to the research question to be able to do this.