View clinical trials related to Yellow Fever Vaccine.
Filter by:Yellow fever is an acute viral disease transmitted by mosquitoes in South America, Central America and Africa. It is more prevalente in males gender and the age above 15 years due to the greater exposure in the wild endemic area of yellow fever. According to the World Health Organization (WHO), 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 issue 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, many studies have demonstrated a reduction of the antibody titrer over the years. Consequently, there is more concern about people who live in endemic areas. For this reason, Brazil recommends revaccinating once at least until additional studies are performed. It is important to know the duration of immunity induced by lower doses of YF vaccine. In our knowledge, there is a lack of clinical studies evaluating the immunity duration of the yellow fever vaccine with lower doses. This information is relevant to subsidize the routine recommendation of YF vaccine fractional dose for adults.
Since the 1st pandemic of the 21st century caused by SARS coronavirus, the world has experienced outbreaks of swine origin H1N1 influenza, Ebola and Zika viruses, which have all resulted in global health crises. Rapid mass vaccination with an effective vaccine such as a live attenuated vaccine, of vulnerable immune-naïve populations to establish herd immunity is an approach to control outbreaks. Such live attenuated vaccine had been used with great success in sporadic yellow fever outbreaks and recently successfully employed in Ebola field trial, both of these diseases have the potential for pandemic spread. Indeed, live attenuated vaccines have proven especially effective in controlling childhood diseases and have even succeeded in eradicating polio and measles from most parts of the world. However, deployment of such vaccines for pandemic control cannot be limited to children but must include adults in order to rapidly elevate herd immunity rates to halt transmission. Vaccinating adults may produce efficacy rates significantly different to those observed in children due to the prevalence of chronic diseases and their associated metabolic complications. Presently, there are 1 billion people who are overweight, many suffer from concurrent metabolic disorders. As activation of the adaptive immunity is reliant on a robust innate immune response to vaccines, metabolic disorders and long-term anti-inflammatory therapy with interventions such as statins may reduce vaccine immunogenicity resulting in suboptimal efficacy in this subpopulation. This study would therefore test the hypothesis that statins reduce live attenuated vaccine immunogenicity. We will combine a clinical trial with systems vaccinology approaches to define the impact statins has on the innate immune, B and T-cell responses to live attenuated vaccination. Our study will thus extend upon another recently completed trial by us and will provide new insights into the determinants of vaccine efficacy in a rapidly growing and aging population globally