Human challenge study: Difference between revisions

Revision as of 05:54, 1 May 2024

Revision as of 06:41, 1 May 2024

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{{Use dmy dates|date=August 2021}}

{{short description|Intentional exposure of test subjects to a pathogen to test a vaccine or drug}}

A '''human challenge study''', also called a '''challenge trial''' or '''controlled human infection model''' (CHIM), is a type of [[clinical trial]] for a [[vaccine]] or other [[drug|pharmaceutical]] involving the intentional exposure of the test subject to the condition tested.<ref name="lamb">{{Cite journal|last1=Lambkin-Williams|first1=Rob|last2=Noulin|first2=Nicolas|last3=Mann|first3=Alex|last4=Catchpole|first4=Andrew|last5=Gilbert|first5=Anthony S.|date=22 June 2018|title=The human viral challenge model: accelerating the evaluation of respiratory antivirals, vaccines and novel diagnostics|journal=Respiratory Research|volume=19|issue=1|pages=123|doi=10.1186/s12931-018-0784-1|issn=1465-993X|pmc=6013893|pmid=29929556 |doi-access=free }}</ref><ref name="eyal">{{Cite journal|last1=Eyal|first1=Nir|last2=Lipsitch|first2=Marc|last3=Smith|first3=Peter G.|title=Human challenge studies to accelerate coronavirus vaccine licensure|url= |journal=The Journal of Infectious Diseases|doi=10.1093/infdis/jiaa152|date=31 March 2020|volume=221|issue=11|pages=1752–1756|pmid=32232474|pmc=7184325| name-list-style = vanc }}</ref><ref name="callaway">{{Cite journal|vauthors=Callaway E |date=April 2020|title=Should scientists infect healthy people with the coronavirus to test vaccines?|journal=Nature|volume=580|issue=7801|pages=17|doi=10.1038/d41586-020-00927-3|pmid=32218549|bibcode=2020Natur.580...17C|s2cid=256820005 |doi-access=}}</ref> Human challenge studies may be ethically controversial because they involve exposing test subjects to dangers beyond those posed by potential [[side effect]]s of the substance being tested.<ref name=eyal/><ref name=callaway/> Controlled human infection studies are also used to study viruses and immune responses.<ref name="Killingley 2022">{{cite journal |last1=Killingley |first1=Ben |last2=Mann |first2=Alex J. |last3=Kalinova |first3=Mariya |last4=Boyers |first4=Alison |last5=Goonawardane |first5=Niluka |last6=Zhou |first6=Jie |last7=Lindsell |first7=Kate |last8=Hare |first8=Samanjit S. |last9=Brown |first9=Jonathan |last10=Frise |first10=Rebecca |last11=Smith |first11=Emma |last12=Hopkins |first12=Claire |last13=Noulin |first13=Nicolas |last14=Löndt |first14=Brandon |last15=Wilkinson |first15=Tom |last16=Harden |first16=Stephen |last17=McShane |first17=Helen |last18=Baillet |first18=Mark |last19=Gilbert |first19=Anthony |last20=Jacobs |first20=Michael |last21=Charman |first21=Christine |last22=Mande |first22=Priya |last23=Nguyen-Van-Tam |first23=Jonathan S. |last24=Semple |first24=Malcolm G. |last25=Read |first25=Robert C. |last26=Ferguson |first26=Neil M. |last27=Openshaw |first27=Peter J. |last28=Rapeport |first28=Garth |last29=Barclay |first29=Wendy S. |last30=Catchpole |first30=Andrew P. |last31=Chiu |first31=Christopher |title=Safety, tolerability and viral kinetics during SARS-CoV-2 human challenge in young adults |journal=Nature Medicine |date=May 2022 |volume=28 |issue=5 |pages=1031–1041 |doi=10.1038/s41591-022-01780-9 |pmid=35361992 |url=https://www.nature.com/articles/s41591-022-01780-9 |access-date=12 April 2024|hdl=10044/1/96278 |hdl-access=free }}</ref>

During the mid 20th and 21st century, the number of human challenge studies has been increasing.<ref name="Adams-Phipps">{{cite journal |last1=Adams-Phipps |first1=Jupiter |last2=Toomey |first2=Danny |last3=Więcek |first3=Witold|last4=Schmit |first4=Virginia|last5=Wilkinson |first5=James|last6=Scholl |first6=Keller|last7=Jamrozik |first7=Joshua|last8=Roestenberg |first8=Meta|last9=Manheim |first9=David|title=A Systematic Review of Human Challenge Trials, Designs, and Safety|journal=Clinical Infectious Diseases|date=11 October 2022 |volume=76 |issue=4 |pages=609–619 |doi=10.1093/cid/ciac820 |pmid=36219704 |pmc=9938741 |doi-access=free }}</ref><ref name="cohen16">{{cite journal|url=https://www.science.org/doi/10.1126/science.352.6288.882|title=Studies that intentionally infect people with disease-causing bugs are on the rise|first=Jon|last=Cohen|journal=Science|doi=10.1126/science.aaf5726|date=18 May 2016|volume=352 |issue=6288 |pages=882–885 }}</ref> A challenge study to test promising vaccines for prevention of [[COVID-19]] was under consideration during 2020 by several vaccine developers, including the [[World Health Organization]] (WHO),<ref name="who-chall">{{Cite web|title=Key criteria for the ethical acceptability of COVID-19 human challenge studies|url=https://apps.who.int/iris/bitstream/handle/10665/331976/WHO-2019-nCoV-Ethics_criteria-2020.1-eng.pdf|publisher=World Health Organization|date=6 May 2020|access-date=18 May 2020}}</ref><ref name="cohen20">{{Cite journal|url=https://www.science.org/content/article/speed-coronavirus-vaccine-testing-deliberately-infecting-volunteers-not-so-fast-some|title=Speed coronavirus vaccine testing by deliberately infecting volunteers? Not so fast, some scientists warn|last=Cohen|first=Jon|date=31 March 2020|journal=Science|doi=10.1126/science.abc0006|s2cid=216451224|access-date=19 April 2020}}</ref> and was approved in the UK in 2021.<ref>{{Cite web|title=World's first coronavirus Human Challenge study receives ethics approval in the UK|url=https://www.gov.uk/government/news/worlds-first-coronavirus-human-challenge-study-receives-ethics-approval-in-the-uk|access-date=18 February 2021|website=GOV.UK|language=en}}</ref>

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Two commonly discussed general thresholds for risk to research participant are minimizing all risk after the infection and avoiding serious injury.<ref name="Binik 2020">{{cite journal |last1=Binik |first1=Ariella |title=What risks should be permissible in controlled human infection model studies? |journal=Bioethics |date=May 2020 |volume=34 |issue=4 |pages=420–430 |doi=10.1111/bioe.12736|pmid=32115747 |s2cid=211727412 }}</ref> Researchers typically customize other thresholds for each clinical trial.<ref name="Binik 2020"/>

Common reasons for participating in human challenge studies include altruism and wishing to contribute to medical progress.<ref name="Eberts 2023">{{cite journal |last1=Eberts |first1=Jake D |last2=Zimmer-Harwood |first2=Paul |last3=Elsey |first3=James W B |last4=Fraser-Urquhart |first4=Alastair |last5=Smiley |first5=Thomas |title=Volunteering for Infection: Participant Perspectives on a Hepatitis C Virus Controlled Human Infection Model |journal=Clinical Infectious Diseases |date=14 August 2023 |volume=77 |issue=Supplement_3 |pages=S224–S230 |doi=10.1093/cid/ciad350 |pmid=37579204 |pmc=10425139 |url=https://academic.oup.com/cid/article/77/Supplement_3/S224/7242430 |access-date=1 May 2024}}</ref><ref name="Marsh 2022" /> People who participate in these studies might be more altruistic in general than others, including possibly more likely to contribute to their communities in other ways, such as donating blood.<ref name="Marsh 2022">{{cite journal |last1=Marsh |first1=Abigail A. |last2=Magalhaes |first2=Monica |last3=Peeler |first3=Matthew |last4=Rose |first4=Sophie M. |last5=Darton |first5=Thomas C. |last6=Eyal |first6=Nir |last7=Morrison |first7=Josh |last8=Shah |first8=Seema K. |last9=Schmit |first9=Virginia |title=Characterizing altruistic motivation in potential volunteers for SARS-CoV-2 challenge trials |journal=PLOS ONE |date=2 November 2022 |volume=17 |issue=11 |pages=e0275823 |doi=10.1371/journal.pone.0275823 |urldoi-access=https://journals.plos.org/plosone/article?idfree |pmid=10.1371/journal.pone.027582336322529 |access-datebibcode=12022PLoSO..1775823M May 2024}}</ref>

==Vaccines for infections==