Approval of Qdenga Dengue Vaccine in India
The Central Drugs Standard Control Organisation (CDSCO) has approved the introduction of the Qdenga dengue vaccine, marking a historic first for India. This approval follows similar licenses in over 40 countries and a World Health Organization (WHO) prequalification.
Challenges in Vaccine Development
- The development time for the vaccine was extensive due to:
- The presence of four antigenically distinct dengue serotypes.
- The risk of severe disease through antibody-dependent enhancement upon a second infection by a different serotype.
Qdenga, developed by Japan-based Takeda, differs significantly from its predecessor, Dengvaxia, as it can be administered without screening for prior dengue infection.
Protection and Challenges
- Qdenga's protection varies by serotype:
- Highest protection against DENV-2, followed by DENV-1.
- Uncertainty remains regarding DENV-3 and DENV-4, especially for those without prior dengue exposure.
- DENV-3's increasing prevalence in India could reduce the vaccine's impact if it dominates future dengue seasons.
- Qdenga requires two doses given three months apart, with logistical challenges in ensuring the mobile migrant population receives both doses.
Cost and Accessibility
Due to Takeda's tiered pricing strategy, Qdenga may be unaffordable for residents of dense urban slums. Government negotiations for lower pricing are crucial to ensure vaccine uptake among high-risk populations.
Conclusion
Proper administration of the dengue vaccine is as complex as its development. The Qdenga rollout demands careful planning and should not lead to complacency in dengue prevention and control efforts.
