ABSTRACT
Dengue vaccine development has been one of the strategies to reduce dengue incidence in the world alongside with other horizontal interventions such as vector control and the transgenic mosquito programmes. The objective of this paper is to evaluate the safety, reactogenicity and immunogenicity of dengue vaccine clinical trials for the last ten years systematically through a descriptive review. This paper discusses safety issues like adverse events, systemic adverse reactions, injection site reactions, viraemia, morbidity and mortality as well as immunogenicity which measures effectiveness through mean geometric titre and seropositive rates. Adverse events were seen to range from 0% to 28.3%. Immunogenicity was noted to increase post 1st and 2nd dose and decrease post 3rd dose. The seropositivity at baseline ranged between 53.1% and 97.8% at post 3rd dose, and it was 88.5% for at least four serotypes. The dengue vaccine studies that were reviewed were shown to be relatively safe with low reactogenicity, however the immunogenicity was unequal and waning. The immunogenicity waned post 3rd dose showing a decrease in all serotypes of varying degrees although the seropositivity, on average, at post 3rd dose was 97.8%. It can be concluded that dengue vaccine development would require further studies on its unequal and waning immunogenicity, which could result in a more severe form of dengue following wild infection, during re-immunisation, especially if there is variation in the circulating virus.