It has also conducted Human challenge studies while having conducted NHP model studies successfully.NIH has licensed their technology for further development and commercial scale manufacturing to Panacea Biotec, Serum Institute of India, Instituto Butantan, Vabiotech, Merck, and Medigen.In Brazil, Phase III studies are being conducted by Instituto Butantan in-collaboration with NIH. Panacea Biotec has conducted Phase II clinical studies in India.A company in Vietnam (Vabiotech) is conducting safety tests and developing a clinical trial plan. All four companies are involved in studies of a TetraVax-DV vaccine in conjunction with the US National Institutes of Health. TDENV PIV
TDENV PIV (tetravalent dengue virus purified inactivated vaccine) is undergoing phase I trials as part of a collaboration between GlaxoSmithKline (GSK) and the Walter Reed Army Institute of Research (WRAIR). A synergistic formulation with another live attenuated candidate vaccine (prime-boost strategy) is also being evaluated in a phase II study. In prime-boosting, one type of vaccine is followed by a boost with another type in an attempt to improve immunogenicity. V180
Merck is studying recombinant subunit vaccines expressed in Drosophila cells. As of 2019, it has completed phase I stage and V180 formulations found to be generally well tolerated. DNA vaccines
In 2011, the Naval Medical Research Center attempted to develop a monovalent DNA plasmid vaccine, but early results showed it to be only moderately immunogenic.
This led to a controversy in the Philippines where more than 733,000 children and more than 50,000 adult volunteers were vaccinated regardless of serostatus.The World Health Organization (WHO) recommends that countries should consider vaccination with the dengue vaccine CYD-TDV only if the risk of severe dengue in seronegative individuals can be minimized either through pre-vaccination screening or recent documentation of high seroprevalence rates in the area (at least 80% by age nine years).The WHO updated its recommendations regarding the use of Dengvaxia in 2018, based on long-term safety data stratified by serostatus on 29 November 2017. Seronegative vaccine recipients have an excess risk of severe dengue compared to unvaccinated seronegative individuals. For every 13 hospitalizations prevented in seropositive vaccinees, there would be 1 excess hospitalization in seronegative vaccinees per 1,000 vaccinees. WHO recommends serological testing for past dengue infection In 2017, the manufacturer recommended that the vaccine only be used in people who have previously had a dengue infection as otherwise there was evidence it may worsen subsequent infections. The initial protocol did not require baseline blood samples prior to vaccination in order to establish an understanding of increased risk of severe dengue in participants who had not been previously exposed.