Human challenge study: Difference between revisions

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The intent of a challenge study is to fast-track the timeline for providing evidence of safety and efficacy of a [[prescription drug|therapeutic drug]] or vaccine, especially by compressing (to a few months) the usually lengthy duration of [[Phases of clinical research|Phase{{nbsp}}II–III trials]] (typically, many years).<ref name=eyal/><ref name=callaway/><ref name="boodman">{{Cite web|url=https://www.statnews.com/2020/03/11/researchers-rush-to-start-moderna-coronavirus-vaccine-trial-without-usual-animal-testing/|title=Coronavirus vaccine clinical trial starting without usual animal data|publisher=STAT|author=Eric Boodman|date=13 March 2020|access-date=19 April 2020}}</ref> Following preliminary proof of safety and efficacy of a candidate drug or vaccine in laboratory animals and healthy humans, controlled "challenge" studies may be implemented to bypass typical Phase{{nbsp}}III research, providing an accelerated path to regulatory approval of the test compound for widespread prevention against an [[infectious disease]], such as COVID-19.<ref name=eyal/><ref name=cohen20/>

The design of a challenge study involves first, simultaneouslydeveloping and testing a well-tolerated dose of the infection. A vaccine candidate would be tested for [[immunogenicity]] and safety in laboratory animals and healthy adult volunteers (100 or fewer){{snd}}which is usually a sequential process using animals first{{snd}}and second, rapidly advancing its effective dose into a large-scale Phase{{nbsp}}II–III trial in low-risk, healthy volunteers (such as young adults), who would then be deliberately infected with the disease being tested against for comparison with a [[placebo]] control group.<ref name=eyal/><ref name=callaway/><ref name=cohen20/> In a challenge study for a vaccine to prevent an infectious disease, participants would be closely monitored for signs of [[toxicity]] and adequate [[immune response]], such as by producing substantial levels of [[antibody|antibodies]] against the virus causing the disease.<ref name=eyal/><ref name=callaway/><ref name=who-chall/>

==Ethics==

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Human SARS-CoV-2 challenge studies have also been conducted to investigate the viral infection and immune response kinetics in COVID-19.<ref name="Killingley 2022" /><ref name=":0" /> Unlike patient-based studies, challenge studies provide a unique opportunity to examine the immune system before viral exposure, immediately after exposure, and in individuals who do not become infected upon exposure. These studies have enabled scientists to identify a biomarker for protection and discover that various distinct immune responses precede symptom onset, including some that are also present in individuals who do not become infected upon exposure.<ref name=":0" />

In March 2024, funding for a five-year international consortium to develop and run human challenge studies for mucosal (transmission-blocking) Covid vaccines was announced on behalf of the [[European Union]]’s Horizon Europe Programme and the [[Coalition for Epidemic Preparedness Innovations]] (CEPI).<ref name="CEPI March 2024">{{cite web |title=Global consortium plans coordinated human challenge studies in hunt for transmission-blocking coronavirus vaccines {{!}} CEPI |url=https://cepi.net/global-consortium-plans-coordinated-human-challenge-studies-hunt-transmission-blocking-coronavirus |website=cepi.net |access-date=1 May 2024}}</ref> Called Mucosal Immunity in human Coronavirus Challenge (MusiCC) and led by [[Imperial College London]], trials are planned to take place in the UK, Europe, Singapore, and the United States.<ref name="CEPI March 2024" /> Representatives of the consortium and its Scientific Advisory Board met in April 2024 to start the project.<ref name="Imperial News Apr 2024">{{cite web |title=Imperial-led global human challenge consortium kick off ambitious 5-year project {{!}} Imperial News {{!}} Imperial College London |url=https://www.imperial.ac.uk/news/252855/imperial-led-global-human-challenge-consortium-kick/ |website=Imperial News |access-date=1 May 2024 |language=en |date=24 April 2024}}</ref> At that meeting, a speaker from CEPI said that human challenge studies were a part of the goal of achieving vaccines for new pandemic diseases in 100 days.<ref name="Imperial News Apr 2024" /> Two trials to test doses of strains of SARS-CoV-2 for challenge studies were begun in 2024, in London and Singapore.<ref name="London 2024 trial">{{cite web |title=An Exploratory Study to Establish the Dose, Safety and Pathogenicity of a SARS-CoV-2 Omicron Challenge Strain (BA.5) in Healthy Participants 18 to 40 Years of Age |url=https://clinicaltrials.gov/study/NCT06492564 |website=clinicaltrials.gov |publisher=NIH |access-date=21 June 2025 |date=28 January 2025}}</ref><ref name="Singapore 2024 trial">{{cite web |last1=Young |first1=Barnaby |title=The Singapore Platform for Controlled Human Infections With SARS-CoV-2 |url=https://clinicaltrials.gov/study/NCT06654973 |website=clinicaltrials.gov |publisher=NIH |access-date=21 June 2025 |date=22 October 2024}}</ref>

==References==