IAS Gyan

Daily News Analysis


25th July, 2023 Science and Technology

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Context: India is exploring the possibility of conducting controlled human infection studies (CHIS), a research method that involves deliberately infecting healthy volunteers with pathogens under controlled conditions. CHIS can help in developing vaccines and treatments for various diseases, but it also raises ethical concerns.


  • India has a high prevalence and mortality rate of infectious diseases. To find new, effective, and affordable ways to research these diseases and prevent them, it is essential to explore alternative methods.
    • One such method is CHIS, which stands for Controlled Human Infection Studies.
  • The Bioethics Unit of the Indian Council of Medical Research (ICMR) has drafted a consensus policy statement that outlines the rationale, benefits, and challenges of CHIS in India.
  • The draft discusses how CHIS can contribute to the scientific understanding and public health response to diseases such as malaria, typhoid, and dengue, which are prevalent in India.
    • It also acknowledges the potential risks and harms of CHIS, such as infection, adverse reactions, and social stigma.
    • It proposes a set of ethical principles and guidelines for designing, reviewing, and conducting CHIS in India, such as informed consent, risk-benefit assessment, scientific validity, oversight, and compensation.
  • The statement is open for public feedback and aims to ensure that CHIS is conducted ethically and safely, with respect to the rights and welfare of the participants.

Challenges and benefits mentioned in the draft

  • According to the ICMR, India has not conducted any CHIS yet, because they involve ethical dilemmas and controversial research ethics — such as intentional harm, potential coercion, risk to others, withdrawal rights and research with vulnerable groups.
  • The paper also mentions that the challenges include technical, clinical, ethical and legal disputes, in the context of specific socio-cultural factors.
  • The ICMR also says that CHIS has many advantages over large clinical trials, such as faster, cheaper, and more efficient results with smaller sample sizes. CHIS can also have social benefits, such as helping public health respond to diseases of concern, informing healthcare decisions and policies, creating economic opportunities, enhancing pandemic readiness, and empowering communities.
  • However, the ICMR also warns that CHIS is a very complex area and may need different types of collaborations among researchers, institutions, organisations and/or countries. Collaborations should be encouraged to get the right expertise that may not be available with one centre or research team.

Controlled Human Infection Studies


  • Controlled human infection studies (CHIS), also known as human challenge studies, are a type of clinical research that involves deliberately exposing healthy volunteers to infectious agents in a controlled environment.
  • CHIS aims to advance the understanding of infectious diseases and their prevention and treatment, by studying how the pathogens infect humans, how the immune system responds, and how vaccines and drugs work against them.


  • CHIS have a long history of contributing to the development of effective interventions for many infectious diseases, such as malaria, typhoid, cholera, influenza, and dengue. For example, CHIS helped to identify the protective role of antibodies in influenza infection and to evaluate the efficacy of the first typhoid vaccine.
  • However, CHIS also raise ethical and practical challenges, such as ensuring the safety and well-being of the volunteers, obtaining informed consent, selecting appropriate challenge strains and doses, providing adequate care and treatment, and conducting CHIS in endemic settings where the disease burden is high.

CHIS typically involve the following steps:

  • Recruiting healthy adult volunteers who meet certain eligibility criteria and are fully informed of the risks and benefits of participating.
  • Administering a vaccine or a drug to some or all of the volunteers, depending on the study design.
  • Exposing the volunteers to a well-characterized strain of the infectious agent, either by natural or artificial routes (such as nasal spray, injection, or ingestion).
  • Monitoring the volunteers closely for signs and symptoms of infection, as well as collecting biological samples for laboratory analysis.
  • Providing prompt and effective treatment if the volunteers develop disease, and ensuring their recovery and follow-up.
  • Analyzing the data to assess the immune responses, disease outcomes, and intervention effects.

CHIS offer several advantages over other types of clinical research, such as:

  • Accelerating the development and evaluation of new vaccines and drugs, by reducing the time, cost, and number of participants required.
  • Enabling the study of rare or emerging infectious diseases that may not be feasible or ethical to study in natural settings.
  • Providing more reliable and precise data on infection dynamics, immune responses, and intervention effects, by controlling for confounding factors and variability.
  • Facilitating the comparison and optimization of different intervention strategies, by using standardized challenge protocols and endpoints.

Steps Taken by Government

  • Establishing a National Task Force on CHIM Studies under the Indian Council of Medical Research (ICMR) provides guidance and oversight for CHIS in India.
  • Funding a pilot CHIM study on typhoid fever at the Translational Health Science and Technology Institute (THSTI), which aims to evaluate the safety and feasibility of conducting CHIS in India.

Challenges that need to be addressed

  • Ensuring adequate protection and compensation for the volunteers who participate in CHIS, especially in low-resource settings where access to health care may be limited.
  • Obtaining informed consent from the volunteers who may have low literacy levels or may face social or economic pressures to participate in CHIS.
  • Developing suitable challenge strains and doses that are safe, reproducible, and relevant to the natural infection.
  • Providing effective treatment options for the volunteers who develop the disease during or after CHIS, especially for diseases that have limited or no available therapies.
  • Balancing the scientific validity and ethical acceptability of conducting CHIS in endemic settings where natural exposure to infection is high.
  • Building capacity and infrastructure for conducting CHIS in India, such as trained staff, specialized facilities, quality control systems, and regulatory frameworks.

Way forward

  • CHIS are an important tool for advancing biomedical research on infectious diseases and their prevention and treatment. However, they also pose significant scientific, ethical, regulatory, and operational challenges that need to be carefully considered and addressed. Therefore, it is essential to foster a collaborative and transparent approach among all stakeholders involved in CHIS, such as researchers, ethics committees, regulators, funders, sponsors, and volunteers.
  • It is important to engage with the public and the media to raise awareness and understanding of CHIS and to address any concerns or misconceptions that may arise. By doing so, CHIS can be conducted in a safe, ethical, and responsible manner, and contribute to the improvement of public health in India and beyond.


Q. What potential benefits can Controlled Human Infection Studies offer in the field of medicine?

1. Identifying new pathogens to enhance biological warfare capabilities.

2. Developing more potent strains of infectious diseases for research purposes.

3. Accelerating the development of vaccines and treatments for various diseases.

4. Exposing human populations to widespread infectious diseases for immunity development.

How many of the above statements is/are correct?

A) Only 1

B) Only 2

C) Only 3

D) All

Answer: A

Explanation: Statement 3 is correct. Controlled Human Infection Studies play a crucial role in advancing medical research and public health. By intentionally infecting human volunteers with specific pathogens in a controlled environment, researchers can closely monitor disease progression and evaluate the efficacy of potential vaccines and treatments. This controlled setting allows for quicker and more precise assessment of medical interventions, ultimately speeding up the development of vaccines and treatments for various infectious diseases. It is important to note that CHIs are conducted under strict ethical guidelines and with the utmost consideration for the safety and well-being of the volunteers.