Dengue Burden Intensifies, Vaccine Race Gains Urgency In India

Climate change-induced shifts in temperature and rainfall patterns, coupled with environmental degradation and evolving vector behaviour, are enabling disease-carrying mosquitoes to expand their footprint into regions previously unaffected. Once largely confined to tropical and subtropical zones, dengue cases are now being reported from temperate regions across the world, including parts of Europe and the Americas. In India, too, an alarming surge in dengue incidents has been witnessed across multiple States, underscoring a growing public health challenge.

Government data reveal that over 2.3 lakh dengue cases were reported in 2024. With floodwaters receding in parts of Delhi, Punjab, Uttarakhand, Haryana, and Assam, health authorities are on alert this year too, anticipating a potential surge in vector-borne diseases such as dengue.

Sounding the alarm, in a recent review meeting with senior officials from States and UTs, Union Health Minister JP Nadda warned States and Union Territories to remain on high alert, noting that the monsoon and post-monsoon period pose the highest risk for water- and vector-borne diseases. He has called for urgent and intensified implementation of the National Dengue Control Strategy, with emphasis on surveillance, vector control, case management, and community participation.

Amid this scenario, a question that has gained renewed attention is: How close is India to accessing a viable dengue vaccine? And more pertinently, why has such a vaccine remained out of reach for so long?

Although several vaccine candidates are at various stages of development globally and domestically, India has yet to approve any for public use. Speaking to The Health Outlook, Dr. Vijay Kumar Agarwal, Director and HoD of Pulmonology and ICU at Faridabad-based Yatharth Super Speciality Hospital, discusses the country’s scientific, epidemiological, and regulatory hurdles—and explains why cautious hope may now be warranted.

India remains among the top 30 countries globally in terms of dengue burden, with perennial transmission in southern States and seasonal spikes during the monsoon and post-monsoon periods in northern regions. Urban sprawl, inadequate sanitation, and construction sites have become high-risk zones for mosquito breeding.

The economic repercussions are equally significant. Costs associated with hospitalisation, absenteeism, and productivity losses amount to hundreds of crores annually. During major outbreaks—Delhi in 2015 and Uttar Pradesh in 2021—critical care infrastructure reportedly struggled to cope, Dr. Agarwal recalled.

“Dengue is not caused by a single agent, but by four genetically distinct serotypes—DENV-1 to DENV-4. Infection with one type offers lifelong immunity only against that particular variant. Subsequent exposure to a different serotype has been linked to increased disease severity via a mechanism known as antibody-dependent enhancement (ADE),” Dr. Agarwal explained.

Given this complexity, Dr. Agarwal emphasised that only a tetravalent vaccine capable of neutralising all four serotypes is considered suitable. Additionally, such a candidate must demonstrate efficacy across varying climatic regions and ensure safety among paediatric cohorts. The key questions now are: Can such a vaccine be formulated, and can it be delivered at scale? What has been accomplished on the global front so far?

Among vaccines already developed, Dengvaxia® (Sanofi Pasteur), approved in 2015, offered modest protection (below 60%). However, it was linked to an increased risk of severe dengue in individuals with no prior exposure.

Consequently, the WHO limited its use to regions with high seroprevalence, conditional upon pre-vaccination screening. In India, where large-scale screening is logistically unfeasible, the vaccine was excluded from the national rollout, Dr. Agarwal explained.

Another candidate, TAK-003 (Qdenga® by Takeda), has been approved in parts of Europe, Asia, and Latin America. “It has shown close to 80% efficacy and a strong safety profile in large studies.” Dr. Agarwal estimates domestic approval could still take 3–5 years, depending on local trial outcomes.

A third contender, Butantan-DV from Brazil, developed with NIH support, is undergoing advanced-phase trials and has yielded promising interim results.

India, amid its strategic shift towards Go Local and Swadeshi, has also stepped up its vaccine innovation efforts, according to Dr. Agarwal.

Highlighting the country’s growing R&D ecosystem, Dr. Agarwal said Indian firms such as Serum Institute of India (SII), Bharat Biotech, and Panacea Biotec are actively developing vaccine candidates, often in partnership with organisations like the Indian Council of Medical Research (ICMR) and the WHO.

Panacea Biotec, in collaboration with ICMR, is advancing a cell-culture-derived, live-attenuated tetravalent dengue vaccine based on a strain developed by the U.S. National Institutes of Health (NIH). The Phase 3 clinical trial—currently in its final stages—has enrolled thousands of participants across the country and is anticipated to offer comprehensive protection against all four dengue serotypes.

The Pune-based SII is simultaneously developing its own tetravalent, live-attenuated recombinant vaccine, also based on the NIH strain. Branded as TetraVax-DV, the candidate, when developed, is expected to be a key addition to India’s domestic vaccine arsenal.

Alternative technologies are also under review. Research is underway on DNA and mRNA platforms, vector-based vaccines, and pan-flavivirus formulations targeting common proteins in dengue, Zika, and yellow fever viruses.

What does the road ahead look like for India? Over the next few years, dengue prevention is expected to progress through a phased framework guided by scientific, regulatory, and logistical factors.

In the short term (1–3 years), the focus will remain on intensifying mosquito control measures, expanding awareness campaigns, and strengthening clinical surveillance, especially in high-risk zones. Local vaccine trials will also continue to gather momentum.

In the medium term (3–5 years), provisional approval of promising vaccines like Qdenga may be granted for selective use in districts with high seroprevalence. This stage will require structured rollout strategies and post-market monitoring.

Looking long term (5–10 years), the inclusion of affordable, Indian-developed tetravalent vaccines in the Universal Immunization Programme (UIP) is anticipated. This would mirror the successful integration of other vaccines like those for rotavirus, measles, and polio.

What role do medical professionals and the public play in this trajectory? While scientific advancements such as vaccines offer hope in the fight against vector-borne diseases, Dr. Agarwal emphasized that these developments must be tempered with realistic expectations. “A vaccine is a vital component—but not the sole answer,” he said.

“Prevention is paramount,” he stated, urging that efforts must continue to focus on reducing vector populations, ensuring early detection of cases, and keeping the public well-informed. “Active participation from communities in eliminating breeding grounds and adopting protective measures is equally crucial.”