India rolls out dengue vaccine phase 3 clinical trials: Why is this significant?

One of the biggest challenges while developing a vaccine is to ensure it is effective for all four strains

Written by Anonna Dutt

Updated: August 16, 2024 07:22 AM IST

3 min read

Scientists think it could be because the vaccines prevent shingles, which has been associated with an increased risk of cardiovascular diseases. (File photo/Representational)

The first phase III clinical trial for a dengue vaccine in India got under way on Wednesday, with the first person receiving the shot at Pandit Bhagwat Dayal Sharma Post Graduate Institute of Medical Sciences (PGIMS), Rohtak. The vaccine called DengiAll, which works against all four serotypes of dengue, has been developed by Panacea Biotech.

The trial will be conducted at 19 sites across 18 states and union territories. It will follow 10,335 healthy adults for a period of two years. Importantly, the large clinical trial is primarily funded by the Indian Council of Medical Research (ICMR), with the company partially bearing the expenses, highlighting the need for a dengue vaccine.

How does the vaccine work?

Panacea’s vaccine uses live, weakened versions of all four dengue serotypes. These weakened versions of the virus were developed by the National Institute of Allergy and Infectious Diseases in the US— they deleted parts of the genetic code of DENV1, DENV3, and DENV4 strains and then genetically engineered a DENV2 backbone, using parts from the weakened DENV 4, on which the others were tacked. These were grown in cell culture by Panacea Biotec to develop the vaccine.

Why is a dengue vaccine needed?

Dengue is a mosquito-borne viral infection, which is increasing in numbers and geographical spread. Globally, the incidence of dengue has gone up from 5,05,430 cases in 2000 to 5.2 million in 2019, according to the World Health Organisation (WHO). In India, the disease has spread from just eight states and Union Territories in 2001 to all states by 2022, with the last bastion of Ladakh being breached that year.

Another challenge is that the symptoms are not apparent in 75-80 per cent of the cases.

What are the challenges with developing a dengue vaccine?

One of the biggest challenges with developing a dengue vaccine is that the four serotypes of the infection offer very little protection against each other, meaning one individual can be infected repeatedly with different serotypes.

More importantly, it can lead to antibody dependent enhancement (ADE) — a person with low levels of antibodies against one serotype of dengue can get a more severe infection with another serotype. Only after a vaccination programme had been rolled out in the Philippines was it found that the vaccine could actually increase the risk of severe disease in the people who had not been infected before.

Are there other vaccine candidates?

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The Serum Institute of India has used the same weakened virus from the US to develop another vaccine candidate that has completed initial phases of trial. The company will conduct a large phase III trial in collaboration with ICMR in children between the ages of two and 18 years.

The same technology has also been used by Indian Immunologicals Limited, which is conducting initial phases of human trials. Hyderabad-based vaccine manufacturer BiologicalE has partnered with the global pharmaceutical company, Takeda, to produce its dengue vaccine. There are at least two indigenous vaccines against dengue under development in research institutes in India.

Anonna Dutt

Anonna Dutt is a Principal Correspondent who writes primarily on health at the Indian Express. She reports on myriad topics ranging from the growing burden of non-communicable diseases such as diabetes and hypertension to the problems with pervasive infectious conditions. She reported on the government’s management of the Covid-19 pandemic and closely followed the vaccination programme. Her stories have resulted in the city government investing in high-end tests for the poor and acknowledging errors in their official reports. Dutt also takes a keen interest in the country’s space programme and has written on key missions like Chandrayaan 2 and 3, Aditya L1, and Gaganyaan. She was among the first batch of eleven media fellows with RBM Partnership to End Malaria. She was also selected to participate in the short-term programme on early childhood reporting at Columbia University’s Dart Centre. Dutt has a Bachelor’s Degree from the Symbiosis Institute of Media and Communication, Pune and a PG Diploma from the Asian College of Journalism, Chennai. She started her reporting career with the Hindustan Times. When not at work, she tries to appease the Duolingo owl with her French skills and sometimes takes to the dance floor. ... Read More

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