Takeda's live attenuated tetravalent dengue vaccine candidate (TAK-003) will be the first dengue vaccine to be cleared for use in India if approved. It is under evaluation in a long-term clinical trial across eight dengue-endemic countries and its efficacy and safety in both seronegative and seropositive participants, with some decline in efficacy from first to second year post-vaccination has been reported.
An exploratory analysis by Dr Luis Rivera, MD and team provided an update with cumulative and third year data. The data revealed that TAK-003 was efficacious against symptomatic dengue over three years but however, efficacy declined over time but remained robust against hospitalized dengue. A booster dose evaluation is yet to be done.
The findings of the study are published in Clinical Infectious Diseases.
The trial updated the data of third year clinical trial and efficacy and effects of TAK-003.
The trial included 20,099 healthy individuals of 4–16 year-olds who were randomized 2:1 to receive TAK-003 or placebo (0, 3 month schedule). The protocol included baseline serostatus testing of all participants and detection of all symptomatic dengue throughout the trial with a serotype specific RT-PCR.
The results of the trial were
• Cumulative efficacy after three years was 62.0% (95% confidence interval: 56.6%, 66.7%) against virologically-confirmed dengue (VCD) and 83.6% (76.8%, 88.4%) against hospitalized VCD.
• Efficacy was 54.3% (41.9%, 64.1%) against VCD and 77.1% (58.6%, 87.3%) against hospitalized VCD in baseline seronegatives, and 65.0% (58.9%, 70.1%) against VCD and 86.0% (78.4%, 91.0%) against hospitalized VCD in seropositives.
• Efficacy against VCD during the third year declined to 44.7% (32.5%, 54.7%), while efficacy against hospitalized VCD was sustained at 70.8% (49.6%, 83.0%).
• Rates of serious adverse events were 2.9% in TAK-003 group and 3.5% in placebo group during the ongoing long-term follow-up (i.e. second half of the 3 years following vaccination), but none were related. No important safety risks were identified.
Dr Rivera and team concluded that "TAK-003 was efficacious against symptomatic dengue over three years. Efficacy declined over time but remained robust against hospitalized dengue. A booster dose evaluation is planned."
Reference: https://doi.org/10.1093/cid/ciab864