Active clinical trials for "Yellow Fever"

Travelers (n = 30, 15 taking low-dose methotrexate (MTX), 15 healthy controls (HC), seeking travel advice in one of the following Swiss Travel Centers (Aarau, Basel, Bern, Geneva, Lausanne, Zurich) and who have an indication for yellow fever (YF) vaccination according to the Swiss Federal Office of Public Health's vaccination recommendations are invited to participate in this study. After signing the consent form (i) YF viremia and (ii) anti-YF antibody production in patients taking low-dose MTX and HC will be compared after YF vaccination. It will be analyzed whether the percentage of people with protective antibodies differs between the two groups and (iii) vaccine side effects will be compared between the groups.

Participating countries: Belgium Context: In June 2013, WHO notified that "a single dose of YF vaccine is sufficient to confer sustained life-long protective immunity against YF disease and that a booster dose is not necessary". . For HIV infected persons the recommendation was less stringent and the position paper concluded that hiv infected persons may "hypothetically, benefit from a second dose or booster dose ".1 Recently, WHO changed the recommendations about a booster dose of YF vaccine, based on the fact that serum neutralizing antibodies against YF are still at detectable levels after 20-35 years and probably lifelong in immunocompetent patients. Unfortunately, data on persistence of Neutralizing antibodies Titers (NT) in immunocompromised patients are missing and only few studies reported data about HIV-infected patients. Additional data are needed. Primary objective: To assess presence / persistence of Neutralizing Titers (NT) of antibodies after YF immunization in HIV-infected patients. Secondary objectives: To identify risk factors for early and late waning of NT after YF immunization To modelize kinetics of NT after YF immunization in different subpopulations of HIV patients, including population of young HIV patients infected vertically To identify risk factors for absence of seroconversion in the year after YF immunization To compare persistence of NT in HIV patients infected vertically or not vertically To quantify seroconversion rate after YF vaccination Methodology / study design This study is a single arm, non randomized, cross-sectional, multicenter study in AIDS Reference Centers from Belgium. The maximum duration of the study for each patient will be 1 visit, consisting of: the screening and inclusion visit (single visit V1) to check the patient eligibility, sign informed consent, perform the biologic tests necessary for the study and answer the questionnaire whenever possible, an additional serum / plasma sample coming from serabank / plasmabank will be identified for each patient. This sample must have been taken during the year following YF immunization. data about patient's HIV history has to be extracted from the HIV database or from patients' file Estimated enrolment 750 patients + 30 patients infected vertically with HIV Primary outcome Number of HIV patients with protective YF NT ≥ 1:10 at different timepoints after YF immunization Secondary outcomes Number of patients with protective YF NT ≥ 1:10 in the year following YF immunization Risk factors (demographics and immunovirological parameters, antiretroviral treatment) for absence of seroconversion in the year following YF immunization Risk factors (demographics and immunovirological parameters, antiretroviral treatment) of early waning (before 10 years) of YF NT Risk factors (demographics and immunovirological parameters, antiretroviral treatment) of late waning (after 10 years) of YF NT Eligibility Inclusion criteria 1. Infection with HIV-1 (vertical transmission or not) 2. Immunization with at least one injection of YF vaccine (Stamaril®,17D strain Rockefeller, Sanofi Pasteur) with proof of vaccine administration 3. Informed consent signed prior to any study procedure Exclusion criteria Inability to give informed consent Substudies Whenever possible, an additional sera or plasma sample from the year following YF vaccine will be selected and analyzed to assess early seroconversion rate Whenever possible, an additional sera or plasma sample from the year before YF vaccine will be selected and analyzed to assess seroconversion rate In CHU Saint-Pierre, an additional cohort of patients infected vertically with HIV will be selected and will participate to the study

A mobile suitcase laboratory for EBOV point-of-care (POC) detection at Ebola treatment centers was successfully implemented in Guinea during the large Ebola virus disease (EVD) outbreak in West-Africa 2014-2015. It was shown that isothermal amplification (Recombinase Polymerase Amplification (RPA)) could be efficiently used to test suspect EVD cases and local teams were trained in and successfully deployed with this fast method. In the frame of this project we want to train teams in DRC and expand RPA testing capacity to the differentials recommended by the WHO. Existing RPA assays for all parameters will be included into a multistrip for simultaneous use. This will be integrated with a simple biosafe extraction method. Implementing this approach and testing in the ongoing EVD outbreak will provide teams in DRC with response capacity for future EVD outbreaks.

Yellow fever is an acute febrile infectious disease transmitted to man urban cycle by mosquitoes infected by an arbovirus of the genus Flavivirus family Flaviviridae. Its occurrence is recorded in South America Central America and Africa. In cities the yellow fever vector is the Aedes aegypti mosquito which also transmits dengue viruses zika and chikungunya. This disease is more frequent in males and the most affected age group is above fifteen years due to the greater exposure related to the penetration in wild areas of the endemic zone of yellow fever. Another risk group is unvaccinated people who live near wild environments where the virus circulates. According to the World Health Organization a single dose of the yellow fever vaccine is sufficient to maintain protective immunity against yellow fever for a lifetime therefore a booster dose is not required. This question is difficult to evaluate because there is no serological correlate of protection against yellow fever and seropositivity is defined with several cut off points. Although studies indicate that the duration of protection after vaccination is long there is considerable evidence in the literature that antibody titer falls over the years reaching levels considered as seronegative in at least a portion of the vaccinees. This is of more concern to people living in endemic areas who are exposed to the virus throughout their lives. For this reason Brazil recommended revaccinating once at least until additional studies were done. The need to increase Bio Manguinhos production capacity to meet the increased demand from Brazil and other countries is urgent. The occurrence of epidemics when millions of individuals need to be vaccinated in a short period of time exceeds production capacity and this is a recurrent problem. The current vaccine has a very high potency well above the thousand international units recommended by World Health Organization. But we need to generate additional evidence that very low doses of viral particles in the yellow fever vaccine are still immunogenic and that their immunogenicity can be maintained for at least ten years after vaccination. This evidence will support the rapid increase of their availability by the fractionation of doses or other alternatives.

In a previous study by the researchers' group, the researchers' investigate the duration of yellow fever post-vaccination immunity in vaccinated children between 9 and 23 months of age. However, in this study, samples of children in the pre-vaccine period, also known as unvaccinated children samples (NV) have not been investigated. It is believed that to seek evidence about the immune status in the medium and long term after vaccination against yellow fever is necessary to investigate paired samples of children not vaccinated (NV), with re-evaluation 30-45 days after primary vaccination. The proposed study is to consolidate aspects of humoral (neutralizing antibodies) and cellular (phenotypic and functional parameters of T cells and memory B) by means of complementary longitudinal investigation children, 9-23 months old, unvaccinated (NV) and 30-45 days after primary vaccination.