ABSTRACT
Objective: To investigate the long-term safety of a tetravalent dengue vaccine (CYD-TDV) in children in a phase Π b follow-up study in Thailand. Methods: In the phase Π b study, children aged 4-11 years were randomized (2:1) to receive three injections of CYD-TDV or serve as control at 6-month intervals, with 25 months' active follow-up (active phase). This study was an additional four-year passive surveillance for hospitalized virologically-confirmed dengue (VCD; hospital phase). Cases of hospitalized VCD, severe hospitalized VCD, vaccine-related serious adverse events, and deaths were reported for the total population, with post-hoc analyses by enrollment age (<9 and years). Results: Of 3 997 participants receiving injection, 80.1% were recruited to the hospital phase [2 131 (CYD-TDV); 1 072 (control)]. Eighty-five hospitalized VCD cases were reported in the CYD-TDV group and 46 in the control group during the four-year hospital phase [relative risk (RR): 0.93, 95% confidence interval (CI): 0.64-1.36]. The RR over six years of follow-up was 0.77 (95% CI: 0.57-1.05). In those aged ≥9 years, the cumulative RRs in the active phase, hospital phase, and entire six years were 0.28 (95% CI: 0.08-0.81), 0.51 (95% CI: 0.25-1.05), and 0.42 (95% CI: 0.24-0.75), respectively. In the overall population, there were ten severe hospitalized VCD cases in the CYD-TDV group and five in the control group over six years (RR: 1.00, 95% CI: 0.31-3.75). Conclusions: Over six years of follow-up, in children aged ≥9 years, CYD-TDV administration is associated with a reduced risk of hospitalized VCD.
ABSTRACT
Dengue virus (DENV) is a mosquito-transmitted virus that is expanding across the world. The incidence of dengue infection, especially severe disease, has been increasing. DENV consist of 4 serotypes of single stranded RNA viruses (D1-D4) in the genus Flavivirus, family Flaviviridae. Majority of dengue infections are asymptomatic cases, which cause difficulty in disease control and are important in dengue surveillance. There is still no gold standard to diagnose asymptomatic dengue infection. Plaque reduction neutralization test (PRNT) has been developed for many purposes such as immunological study, clinical study, vaccine trial and is currently the most sensitive and specific method for serological surveillance. However, PRNT shows some degree of cross reaction among different dengue serotypes especially secondary dengue infection cases and to other flaviviruses. Moreover, various modification since the beginning make PRNT lack of inter-laboratory standardization which is an important issue. This paper discusses the important of asymptomatic dengue infection and its diagnostic method.
ABSTRACT
Dengue virus (DENV) is a mosquito-transmitted virus that is expanding across the world. The incidence of dengue infection, especially severe disease, has been increasing. DENV consist of 4 serotypes of single stranded RNA viruses (D1–D4) in the genus Flavivirus, family Flaviviridae. Majority of dengue infections are asymptomatic cases, which cause difficulty in disease control and are important in dengue surveillance. There is still no gold standard to diagnose asymptomatic dengue infection. Plaque reduction neutralization test (PRNT) has been developed for many purposes such as immunological study, clinical study, vaccine trial and is currently the most sensitive and specific method for serological surveillance. However, PRNT shows some degree of cross reaction among different dengue serotypes especially secondary dengue infection cases and to other flaviviruses. Moreover, various modification since the beginning make PRNT lack of inter-laboratory standardization which is an important issue. This paper discusses the important of asymptomatic dengue infection and its diagnostic method.