On guard, Pg6

Key Highlights:

• The Central Drugs Standard Control Organisation (CDSCO) has approved Qdenga, India's first dengue vaccine, developed by Japan-based Takeda.
• The vaccine has received WHO prequalification and is licensed in over 40 countries globally.
• Qdenga is administered in two doses, three months apart, and does not require prior dengue infection screening.
• Concerns exist regarding the vaccine's varying protection against the four dengue serotypes, particularly DENV-3 and DENV-4, in individuals without prior exposure.
• The vaccine's high cost, due to Takeda's tiered pricing strategy, may pose an accessibility challenge for vulnerable populations in India.

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Detailed Insights:

• India faces a significant dengue burden, with Aedes mosquitoes expanding into semi-urban and rural areas, making conventional vector control difficult.
• Developing an effective dengue vaccine is complex due to the existence of four distinct serotypes and the risk of antibody-dependent enhancement (ADE).
• The previous dengue vaccine, Dengvaxia, faced controversy in the Philippines in 2017 due to increased disease severity risk in previously uninfected individuals.
• The TIDES trial for Qdenga indicated a potential 'negative efficacy' against hospitalization for DENV-3 among seronegative children after the first dose.
• Ensuring that highly mobile populations, such as migrant workers, receive both doses of the vaccine presents a significant logistical challenge.
• Government intervention through price negotiation is crucial to ensure equitable access and widespread uptake of Qdenga among high-risk groups.

Scientific/Technical Concepts Involved:

• CDSCO (Central Drugs Standard Control Organisation): India's national regulatory authority responsible for ensuring the quality, safety, and efficacy of drugs, medical devices, and cosmetics.
• WHO Prequalification: A World Health Organization program that assesses health products to ensure they meet global standards for quality, safety, and efficacy for international procurement.
• Dengue Serotypes: The four distinct viral strains (DENV-1, DENV-2, DENV-3, DENV-4) that cause dengue fever, with infection by one not providing immunity against the others.
• Antibody-Dependent Enhancement (ADE): A immunological phenomenon where pre-existing, non-neutralizing antibodies can worsen a subsequent infection by a different serotype, leading to more severe disease.
• Aedes Mosquitoes: The primary genus of mosquitoes, particularly Aedes aegypti, responsible for transmitting dengue, commonly found in human habitats and breeding in small water containers.