New Delhi: Years after an agreement between the Indian Council of Medical Research (ICMR) and an international organisation to scale up and commercialise a vaccine against shigella fell through, the government health research agency has found an Indian partner to manufacture the breakthrough vaccine candidate.
The vaccine candidate developed by the ICMR-National Institute for Research in Bacterial Infections (NIRBI), previously known as the National Institute of Cholera and Enteric Diseases, has shown robust results in animal studies.
The development puts the ICMR in the race to offer the first ever vaccine against shigella, which kills tens of thousands every year, mainly children under the age of five.
A gram-negative or hard to treat bacteria, shigella causes the highly infectious shigellosis disease, which is marked by bloody diarrhoea with or without fever.
Scientists associated with ICMR-NIRBI told ThePrint that the vaccine — once past the human trials and if everything goes well — could be available for use within the next two years.
“We have floated an expression of interest for co-developing and commercialising the vaccine candidate that has shown a high level of efficacy, and an Indian maker is keen to scale up the vaccine production,” Dr Shanta Dutta, director of ICMR-NIRBI, said.
“Once available for human use, it has the potential to immensely curb deaths in kids in middle-and low-income countries due to diarrhoeal disease caused by shigella,” she added.
Children are particularly vulnerable to shigella infections because of their immature immune systems and close contact with others in settings such as daycare centres and schools.
The bacteria are transmitted through the faecal-oral route, which means that infection can occur when children ingest food or water contaminated with shigella bacteria or come into contact with surfaces contaminated by faecal matter.
It has been estimated that shigella triggers a huge disease burden globally, causing nearly 125 million diarrhoeal episodes annually and around 1,60,000 deaths, with a third of these associated with children under five years of age.
In India, according to the ICMR, the accurate estimates of morbidity and mortality due to shigellosis are lacking, though it is endemic in the country and has been reported to cause many outbreaks.
In 2022, the death of a 16-year-old girl and the hospitalisation of 58 others following food poisoning after eating shawarma infected with shigella in Kasaragod, Kerala, had made headlines.
“Shigella infections are common in India, especially in areas with poor sanitation and overcrowding. The bacteria can spread easily through contaminated food and water,” said Dr Neeraj Gupta, paediatric intensivist with Sir Ganga Ram hospital in Delhi.
As of now, there are no approved vaccines against shigella in the world, though several are under development. The World Health Organization has put shigella in its priority list of pathogens as it is growing increasingly resistant to existing antibiotics.
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A collaboration that didn’t work out
In 2019, the ICMR had licensed the technology for the scaling up and commercialisation of its shigella vaccine to MSD-Wellcome Trust Hilleman Laboratories.
The vaccine candidate, for which the deal was struck, was next-generation outer membrane vesicles-based antigens from shigella.
However, Dutta said, first due to the Covid pandemic and later because of Hilleman shifting its base from India to Singapore, the agreement came to a dead end.
ThePrint has reached out to MSD-Wellcome Trust Hilleman Laboratories for its response on the subject via email. This report will be updated if and when a reply is received.
Dutta said that ICMR-NIRBI then tried to gauge the response of other vaccine-makers through an expression of interest last year, but no company showed any interest. Now, however, an Indian vaccine-maker has come forward to take up the project as demand for a vaccine against shigella has been put forth by several countries.
“As shigella is an antigenically diverse pathogen containing four species (or groups), 50 serotypes (classification of pathogens) based on the antigens or other molecules found on their surfaces, and sub serotypes, it makes the development of a vaccine challenging,” explained a scientist who has been involved in the development of the vaccine candidate.
“Our understanding is that the protection stimulated by a shigella vaccine must be broad enough in spectrum to protect against 16 serotypes, including six that are most common and also behind the severest form of the disease. Our vaccine candidate has shown high efficacy against these strains,” he said.
Strong need for vaccine against shigella
According to some independent experts, given the severity of shigella infections and their impact on children, there is a strong case for the development and implementation of effective vaccines.
“Vaccination is required for prevention of the disease, reduction of transmission and protection of the vulnerable population,” said Dr Suresh Kumar Panuganti, paediatric critical care specialist attached with Yashoda Hospitals in Hyderabad.
Vaccination would be a proactive approach to protect children from the potential severity of shigellosis. It can help interrupt the transmission within communities, thereby contributing to broader public health efforts to control outbreaks, he added.
“As children under five years of age are particularly susceptible, a vaccine could provide targeted protection for this high-risk group, reducing the incidence of severe cases and complications,” Panuganti said.
Dutta emphasised that investing in a shigella vaccine can lead to long-term cost savings by reducing healthcare expenses related to treatment and preventing the economic losses associated with illness in middle and low-income countries like India.
(Edited by Nida Fatima Siddiqui)
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