Catch a cold and help scientists make new vaccines

Two sides: The Controlled Human Infection Model is useful but brings with it ethical challenges.   | Photo Credit: Istock/GETTY IMAGES

The Department of Biotechnology (DBT) is close to finalising three projects worth ₹135 crore, involving Indian and European scientists, to develop new influenza vaccines.

What will make these projects unique is that they involve a Controlled Human Infection Model (CHIM): volunteers who take part in trials will be infected, under expert supervision, with infectious viruses or bacteria. Such studies, which are being employed in vaccine development in the United States, the United Kingdom and Kenya, are being considered in India.

A CHIM approach will speed up the process whereby scientists can quantify whether potential vaccine candidates can be effective in people and identify the factors that determine why some vaccinated people fall sick and others do not. The risk in such trials is that intentionally infecting healthy people with an active virus and causing them to be sick is against medical ethics. It also involves putting human lives in danger.

Ethics and guidance

By November, experts in vaccine development, social scientists and bio-ethicists are expected to prepare, with the DBT’s support, a guidance document that will elaborate upon the circumstances under which CHIM trials may be conducted, facilities needed, the profile of potential volunteers, the informed-consent forms they would need to sign and the compensation that can be offered.

Post the availability of guidance documents, there needs to be approval from the Drug Controller-General of India. “Any such trial will have to comply with the rules governing clinical trials in India. The influenza trials will be performed outside India, but what we are hoping to get out of this is learning,” said Gagandeep Kang, Director, Translational Health Science and Technology Institute of India (THSTI). Scientists at the THSTI are involved in establishing protocols for the trials.

Intestinal bugs too

Rather than influenza trials, India would likely develop CHIM protocols to study bacterial or enteric viruses (residing in the intestine) such as cholera or typhoid, said Professor Kang. If successful, these would serve to create back-ups to the existing cholera and typhoid vaccines. Experience with CHIM could help to create clinical investigators trained in vaccine development.

The Hyderabad-based biotech company, Bharat Biotech, relied on a CHIM approach to establishing that its conjugate typhoid vaccine — while already licensed in India — was effective in a large population. With funding from the Bill and Melinda Gates Foundation and the international consortium GAVI, the vaccine’s potency was evaluated by infecting human volunteers at Oxford University in the U.K. with a typhoid parasite. The results encouraged scientists to test the vaccine in Nepal, Bangladesh and Malawi among 1 lakh children. The vaccine was over 80% protective when tested on the field, claimed Andrew Pollard, leader of the UK vaccine trials and professor at Oxford University. The findings are to be published in a forthcoming issue of the peer-reviewed New England Journal of Medicine.

Vaccines traditionally are made of a weakened form of a disease-causing virus or bacteria and injected into the body to coax the immune system into making antibodies that create immunity against future infection. Years of vaccine development has shown that frequently vaccines that work in small groups of people may not always work in large populations, or those that are effective in one country may not be in another. CHIM models help vaccine-makers decide whether they should go ahead with investing in expensive trials.

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Printable version | Oct 16, 2021 1:58:49 PM |

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