Controlled Human Infection Model
India has a significant burden of infectious disease, especially among young children, and the condition is endemic to the country. To study the pathogen, its transmission and also to develop effective drugs, the Scientists have proposed Controlled Human Infection Model (CHIM) studies.
What is Controlled Human Infection Model?
In CHIM studies, researchers infect healthy participants with a weakened strain of a pathogen in a controlled setting. This is done to learn more about the infection and the disease or to develop new vaccines for that disease.
Dr. Gagandeep Kang, while pointing out the need for CHIM studies in India, said that Rotavirus vaccine was tested in other countries where it showed 90% efficacy while in India it has only 50% efficacy. In another scenario, oral vaccinations like for cholera, polio that was tested in other countries and showed good results but showed low efficacy in India. Dr. Gagandeep is the Executive Director at Transitional Health Science and Technology Institute.
All these questions may be answered with the help of CHIM studies. CHIM is a faster way to develop vaccines as it is studied well in human models.
Recently typhoid strain was developed in India, but it
was tested in Oxford University, the UK. This is because India has an ethical obligation where clinical trials cannot be done on humans. Dr. Kang argued that animals and humans have different physiology, and it is helpful if the clinical tests are done on humans.Dr. Manjulika Vaz from India Volunteer Infection Research Consortium, supporting the CHIM said that the studies should first start with a small group of people. Eventually, it can be escalated to a larger group of people. Dr. Manjulika agrees that high risk may be involved in the CHIM studies. She suggests informing the volunteers and family members thoroughly about the risks involved and different aspects of the studies.
Controlled Human Infection Model- The Procedure Involved
After injecting attenuated typhoid strain, volunteers would be examined for 4-5 weeks under proper medical supervision. Volunteers will be under medical guidance if in case the person develops side effects. Blood samples would be taken daily, and volunteers will be monitored for one year. They may also be isolated from the community for a defined period of infectivity of the pathogen, to avoid transmission of the disease to the respective community.
Dr. Vaz highlighted that CHIM studies are already being undertaken in western countries. She believes it may take some years for India to adopt this study. She added that the regulatory bodies and the Government of India should ensure that poor people are not exploited for the sake of money.
