IAS/UPSC Coaching Institute  

25 Jul 2026 : On guard

Article 1: On guard

Why in news: India approved Qdenga, its first dengue vaccine, after CDSCO clearance. While the approval marks a major public health milestone, concerns remain over efficacy, affordability, dose completion, and implementation.

Key Details

  • First dengue vaccine: Qdenga is India's first approved dengue vaccine; licensed in 40+ countries and WHO prequalified.
  • Scientific challenge: Protecting against all four dengue serotypes while avoiding antibody-dependent enhancement (ADE).
  • Variable efficacy: Highest protection against DENV-2, limited evidence for DENV-3/DENV-4 in seronegativeindividuals.
  • Implementation hurdles: Requires two doses three months apart; ensuring completion among migrant populations is difficult.
  • Affordability: High pricing may restrict access; government price negotiations are essential for equitable coverage.

Approval of India's First Dengue Vaccine

  • CDSCO has approved Qdenga, India's first dengue vaccine.
  • The vaccine is already licensed in over 40 countries and has received WHO prequalification.
  • Its approval comes after India experienced high dengue burden and improved disease surveillance.
  • With Aedes mosquitoes spreading into semi-urban and rural areas, controlling dengue through vector control alone has become increasingly difficult.

Scientific Challenges in Developing the Vaccine

  • Dengue has four distinct serotypes (DENV-1, DENV-2, DENV-3, DENV-4), making vaccine development complex.
  • Infection with one serotype followed by another can lead to more severe disease due to antibody-dependent enhancement (ADE).
  • Therefore, an effective vaccine must provide strong immunity against all four serotypes simultaneously.
  • The earlier vaccine, Dengvaxia, faced safety concerns, leading to greater regulatory caution.
  • Qdenga, developed by Takeda (Japan), differs from Dengvaxia and does not require prior dengue screeningbefore vaccination.

Limitations in Protection

  • Qdenga provides the strongest protection against DENV-2, followed by DENV-1.
  • Its effectiveness against DENV-3 and DENV-4, especially in people without previous dengue infection (seronegative individuals), remains uncertain.
  • This is significant because DENV-3 cases are increasing in India.
  • If DENV-3 becomes dominant during the 2026 monsoon, the vaccine's overall effectiveness could be lower than expected.

Rollout and Implementation Challenges

  • Qdenga requires two doses administered three months apart.
  • Protection after the first dose is incomplete, particularly against DENV-3 and DENV-4.
  • Ensuring that migrant and mobile populations receive the second dose will be challenging.
  • Concerns also arise from the TIDES trial, which reported negative efficacy against DENV-3-related hospitalisation among seronegative children.

Affordability and the Way Forward

  • Under Takeda's tiered pricing strategy, Qdenga may be too expensive for vulnerable populations, especially those in urban slums.
  • The government should negotiate lower prices to ensure equitable access and higher vaccine uptake.
  • Vaccination should complement, not replace, vector control and public health measures.
  • The rollout of Qdenga should be carefully monitored, as effective implementation is as challenging as vaccine development itself.

Conclusion

Qdenga offers India an important opportunity to reduce the burden of dengue, but vaccination alone cannot eliminate the disease. Success will depend on affordable pricing, robust surveillance, complete two-dose coverage, continued vector control, and public awareness. A balanced strategy integrating immunisation with preventive public health measures is essential for long-term dengue control.

Prelims question:

The phenomenon of "Antibody-Dependent Enhancement (ADE)" in dengue refers to:

(a) Antibodies providing lifelong immunity against all dengue serotypes.
(b) Increased severity of dengue when a person infected with one serotype is later infected with a different serotype.
(c) Mutation of the dengue virus due to vaccination.
(d) Development of resistance in Aedes mosquitoes to insecticides.

Answer: b