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Extrait
Background and study aims The purpose of this study is to find a way to overcome the poor immune responses to oral vaccines seen in developing countries. We have previously found that all-trans retinoic acid (ATRA) can increase the intestinal antibody response to oral typhoid vaccine. The purpose of this study is to determine if ATRA can do this with other vaccines, how long a course of treatment is required, whether the effect depends on vitamin A status, and how it works. We also intend to find the most suitable dose which would be required to take this into studies in children, who most need the benefit of oral vaccines. Who can participate? Men and children under 5 years of age who are residents of Lusaka, Zambia, and all will be healthy volunteers. What does the study involve? Participants will be given one of five vaccines (against typhoid, cholera, polio, enterotoxigenic E. coli or rotavirus) with or without ATRA. In initial studies, a group of 20 men will be given ATRA alone to evaluate its immune effects, and these men will have intestinal biopsies for measurement of expression of relevant genes. In all cases, blood will be collected for studies of cellular and antibody responses. Participants who receive vaccines will also undergo whole gut lavage for quantification of intestinal antibody responses. What are the possible benefits and risks of participating? Participants will benefit from vaccination, and from screening and monitoring programmes. There are minimal adverse effects of ATRA at this dose; the serious adverse effects are observed in patients with leukaemia, when ATRA is used at much higher doses. While blood sampling carries minimal discomfort and risk, gut lavage involves modest discomfort, and endoscopy requires sedation and carries finite (though low) risk of procedure-related effects. Where is the study run from? There is only one study centre - the University of Zambia School of Medicine, Lusaka. When is the study starting and how long will it run for? The study started in May 2013 and will continue until late 2014. Participant recruitment will continue until December 2013. Who is funding the study? The study is funded by the Bill & Melinda Gates Foundation (USA). Who is the main contact? Dr Paul Kelly [email protected]
Critère d'inclusion
- Vaccine responses