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Accelerating our understanding of infectious diseases

A human challenge study is a carefully managed medical research study, during which volunteers are intentionally given an infection in a safe way with healthcare support.

Human challenge studies have a unique ability to investigate and understand the onset and development of disease in a controlled environment. They allow researchers to tease out complicated interactions and point out potential targets for prevention, vaccines or treatment that cannot be seen in patients who are infected naturally. 

Imperial College London has successfully led several such studies to better understand a range of infectious diseases and, in February 2021, ran the world’s first human challenge study for COVID-19. 

Imperial also hosts HIC-Vac, a Wellcome-funded international network of researchers developing human infection challenge studies to accelerate the development of vaccines against pathogens of high global impact.

All human challenge studies carried out by Imperial require ethical approval from the UK Health Research Authority. Trials are designed to minimise risk to study participants, and the health and safety of participants are paramount.

Past studies

Imperial College London was funded by the Medical Research Council (MRC) and GlaxoSmithKine (GSK) to conduct a human infection study (also known as a controlled human infection challenge study) with RSV.

Learn more about the INFLAMMAGE study

The COVHIC001 study set out to establish a safe and effective human challenge model for SARS-CoV-2. 36 volunteers aged 18–29 years without evidence of previous infection or vaccination were inoculated with a ‘pre-Alpha’ strain of SARS-CoV-2. The study was led by a partnership between Imperial College London, the Vaccine Taskforce and Department of Health and Social Care (DHSC), hVIVO (part of Open Orphan plc.), and the Royal Free London NHS Foundation Trust. The findings of the study were published in Nature Medicine in March 2022. 

Learn more about the COVHIC001 study

In October 2020, Imperial investigators published findings of an RSV human challenge study in the journal Science. The study aimed to investigate the underlying mechanisms of why people succumb to RSV infection and the factors behind varied immune responses. The researchers found that volunteers who succumbed to infection from RSV had more specialised white blood cells called neutrophils in their airways before exposure to the virus, compared to those who staved off infection. 

Find out more about the study's findings in the official news release