Dengue Fever (DF) is a mosquito-borne disease (Aedes) caused by single-strand RNA viruses of the family flaviviridae. Two-fifths of the world's population are thought to be at risk from DF, mainly urban dwellers in tropical and sub-tropical countries. The disease has a wide spectrum of symptoms ranging from a mild febrile illness to severe outcomes such as hospitalization and death, as observed in dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS). Importantly, of the 22,000 estimated deaths per year, the large majority are in children (< 15 yrs). No specific treatment for dengue fever is available.
A three-dose Sanofi Pasteur vaccine (CYD-TDV, Dengvaxia) has been licensed since 2015 for the prevention of disease caused by all four dengue virus serotypes in preadolescents, adolescents and adults, 9 to 45 years of age living in endemic areas. As of January 2018, 19 countries had approved Dengvaxia. In April 2016, the WHO SAGE committee recommended countries consider the introduction of CYD-TDV only in geographic settings (national or subnational) with high endemicity, as indicated by seroprevalence of approximately 70% or greater. Two countries: Brazil (Parana state) and the Philippines started mass immunization programs, albeit with some controversy. In November 2017, a new analysis of Phase III data came to light indicating that the risk of hospitalized and severe dengue is significantly increased among vaccinated subjects who were seronegative for dengue at the time of first vaccination in all age groups studied. It is of note that the vaccine significantly protects against hospitalized and severe dengue in subjects seropositive for dengue at time of first vaccination in all age groups studied. Dengvaxia will soon have label restrictions regarding use in those without prior infection and has been suspended in the Philippines. WHO (December 2017) now recommends vaccination only in individuals with a documented past dengue infection, either by a diagnostic test or by a documented medical history of past dengue illness. A further review should be available no later than April 2018.
Other dengue vaccines notably, DenVAX, TDV (Takeda Vaccines) and TetraVAX, TAK-003 (NIAID, Butantan) are in late-stage development (Phase III) and should capitalize on the recent issues related to Dengvaxia. However, both programs will now be under intense regulatory scrutiny to ensure they do not exhibit the same disease enhancement phenomenon seen with Dengvaxia.
This month VacZine Analytics has updated both its dengue (endemic) and dengue (travelers) vaccine forecasts which give its most up-to-date view on this future vaccine market. The Dengvaxia restriction has been taken into account and brand new roll-out/competitor assumptions have been incorporated across 32 endemic countries and all Western travelers points of origin.
Dr John Savopoulos who led the recent research commented, "We always knew Dengvaxia had a sub-optimal profile, but it does show efficacy in certain scenarios and at the moment it is all we have. It will be very interesting to see whether Sanofi can re position this vaccine and whether new competitors can overcome the new scepticism regarding public mass vaccination."
For more information please contact info@vaczine-analytics.com or www.vaczine-analytics.com
VacZine Analytics, world-leading supplier of vaccine-related commercial analyses is a trading division of Assay Advantage Ltd (UK Company No: 5807728, UK VAT: 883584084)