Dengue

A mosquito-borne viral infection causing high fever and severe muscle pain. The Dengvaxia controversy highlighted complex challenges in dengue vaccination.

Disease Burden

Dengue is a mosquito-borne viral infection caused by four related dengue viruses (DEN-1, DEN-2, DEN-3, DEN-4). It is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. The disease affects millions of people annually, primarily in tropical and subtropical regions (CDC, 2024).

According to WHO, dengue has become a major international public health concern. There are estimated 100-400 million infections annually in over 100 endemic countries. Severe dengue (dengue hemorrhagic fever) can be life-threatening without proper medical care.

Vaccines

Dengvaxia (CYD-TDV) - The Controversy

  • First dengue vaccine, approved in 2015 (Philippines, Mexico, Brazil)
  • Problem: Increased severity in seronegative recipients (no prior dengue exposure)
  • 2017: Philippines halted vaccination program after deaths
  • 2018: Manufacturer limited use to seropositive individuals only
  • Important: Requires pre-screening for prior infection

TAK-003 (Qdenga)

  • Second dengue vaccine, approved 2022 (Indonesia, EU, UK, Brazil)
  • Live attenuated tetravalent vaccine
  • 2-dose schedule, 3 months apart
  • Efficacy: ~80% against symptomatic dengue
  • Does NOT require pre-screening for prior infection
  • WHO recommends for children 6-16 in high-endemic areas

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