India's First Dengue Vaccine: Phase 3 Trials Approach Finish Line, Promising Hope Against Widespread Disease

Dengue fever, a viral infection transmitted by the Aedes aegypti mosquito, poses a significant health challenge in India. The nation accounts for a substantial portion of the world's 100–400 million annual infections. As monsoon season approaches, bringing with it the peak of dengue transmission, hope emerges in the form of India's first dengue vaccine, which is nearing completion of its Phase 3 clinical trials.

The Danger of Dengue

Dengue fever is characterized by high fever, severe headaches, joint and muscle pain. In severe cases, it can lead to a dangerous drop in blood platelet counts, internal bleeding, organ failure, and even death. Children and the elderly are particularly vulnerable to the most severe complications of the disease.

Hurdles in Vaccine Development

Developing a dengue vaccine has been a long-standing challenge for scientists. The complexity lies in the existence of four distinct dengue virus types (serotypes). An effective vaccine must provide protection against all four to prevent potential antibody-dependent enhancement (ADE), where a vaccine could paradoxically worsen subsequent dengue infections. Some vaccines developed elsewhere have demonstrated mixed results and limited effectiveness, hindering their widespread adoption.

India's Homegrown Solution: TetraVax-DV

The Serum Institute of India (SII) is developing India's first dengue vaccine, named "TetraVax-DV." This vaccine is specifically engineered to provide protection against all four dengue virus serotypes. TetraVax-DV utilizes a weakened (attenuated) form of the virus to stimulate the body's immune system, enabling it to develop antibodies and cellular immunity against dengue fever. As the vaccine does not contain a live, replicating virus, it cannot cause dengue fever itself.

The TetraVax-DV vaccine boasts several key features:

• Targets all four dengue virus types
• Developed using advanced technology
• Undergoing rigorous testing for safety and effectiveness

Understanding Phase 3 Trials

Before any vaccine can be approved for widespread use, it must undergo a series of clinical trials to assess its safety and efficacy. These trials are typically divided into three phases:

• Phase 1: Involves a small group of healthy volunteers to primarily evaluate the vaccine's safety profile and identify potential side effects.
• Phase 2: Expands the study to a larger group to further assess the vaccine's immunogenicity (ability to stimulate an immune response) and monitor for any adverse reactions.
• Phase 3: Enrolls thousands of volunteers to evaluate the vaccine's effectiveness in preventing the disease in a real-world setting.

Phase 3 trials are the most crucial stage, as they provide critical data on the vaccine's ability to prevent dengue fever within the community.

Current Status in India

The Phase 3 trial for India's dengue vaccine commenced in 2023. The trial spans over 20 locations across the country, encompassing both urban and rural areas. The study aims to enroll over 10,000 volunteers, representing a diverse range of age groups and backgrounds. Enrollment is nearing completion, and preliminary results are promising.

What's Next?

Following the completion of enrollment, the Phase 3 trial will continue with:

• Monitoring: Volunteers will be closely monitored for any potential side effects and assessed for protection against dengue fever upon natural exposure.
• Data Analysis: Scientists will analyze the collected data to determine the vaccine's overall efficacy and identify any factors that may influence its performance.
• Regulatory Approval: If the Phase 3 trial results are favorable, the vaccine could be submitted for approval by Indian health authorities within the next year.

The Importance of a Dengue Vaccine for India

India faces a significant burden from dengue fever, with outbreaks placing a strain on healthcare facilities and causing hardship for affected families. A safe and effective dengue vaccine holds the potential to:

• Reduce the number of dengue cases
• Lower hospital admissions related to dengue
• Save lives, particularly among children
• Reduce the economic burden associated with dengue on families and the healthcare system

While the development of a dengue vaccine is a significant step forward, preventative measures remain crucial. These include using mosquito repellents, wearing protective clothing, eliminating mosquito breeding sites by covering drains and removing standing water.

Source

The Indian Council of Medical Research (ICMR) and Panacea Biotec.