Lack of antidotes called 'serious ethical dilemma' for COVID-19 vaccine challenge trial

UK scientists seeking approval todeliberately infect healthy people with COVID-19 in trials mustfirst convince ethics specialists that, among other things, theyhave potential "rescue therapies" or antidotes to halt thedisease.

The problem is that, for the novel coronavirus, there isstill no effective treatment or cure.

That means, for now, that the best scientists planning theso-called human challenge studies can offer is Gilead'sremdesivir an antiviral drug that was found in a large trialto have no impact on COVID-19 death rates.

Chris Chiu, a scientist at Imperial College Londonco-leading the COVID-19 challenge experiments, said the plan wasto give remdesivir to infected volunteers based on a "strongbelief" it will be effective if given in the very earlieststages of disease.

Some ethics and medicine experts said that posed problems.

"As an effective rescue therapy does not yet exist forSARS-CoV2, there is a serious ethical dilemma ... to addresshere," said Stephen Griffin, an associate professor in theschool of medicine at Britain's Leeds University.

WATCH | The challenges of vaccine challenge trials:

The controversial push to fast-track a COVID-19 vaccine

4 years ago

Duration 9:01

Human challenge trials could make finding a COVID-19 vaccine faster, but the controversial approach involves exposing volunteers to the virus to see if a potential vaccine works. The Nationals Andrew Chang finds out more about this process and the people volunteering to be test subjects.

Other specialists said the lack of antidotes or rescuetherapies was only one of several risks the research team wouldhave to minimize, and trial volunteers would have to accept, ifthe studies are to gain ethical approval.

Plans to reduce those risks include picking the most robust,healthy, young volunteers to be infected, and using the bareminimum amount of the coronavirus to infect them with COVID-19.

Dominic Wilkinson, a professor of medical ethics at Oxforduniversity, said that, while desirable, having an effectivetreatment at the ready after deliberately infecting volunteerswas "not essential for the ethics of such a trial."

"The ethical necessity of these trials, and of any trial, isthat you assess the risks, you minimize the risks, and youcommunicate the risks," he told Reuters. "It's not the case thatyou have a situation where there are no risks."

Risk to public trust in medicine?

Human challenge trials are not new. Scientists have usedthem for decades to learn more detail about and developtreatments and vaccines against several other diseases such asmalaria, flu, typhoid and cholera.

"Generally with such trials in the past, they were done whenyou had a specific treatment," said Margaret Harris, aspokeswoman for the World Health Organization (WHO), when askedabout the planned UK trials using the novel coronavirus.

"You must ensure that everybody involved understands exactlywhat is at stake ... and ensure informed consent is rigorous that they really do understand all the risks," she said.

Ohid Yaqub, a science policy expert at Britain's Universityof Sussex, pointed to WHO guidelines on the issue, which amongother things say human challenge trials "might be consideredwhen the disease an organism causes has an acute onset, can bereadily and objectively detected, and existing efficacioustreatments ... can be administered ... to prevent significantmorbidity, and eliminate mortality."

Yaqub warned of a risk to public trust in science andmedicine if these criteria are ignored or skimmed over, adding:"There needs to be wider consultation about undertaking suchstudies."

He noted that selecting a small number of low-riskparticipants would mean "fatality, hospitalization or long-termsymptoms are extremely unlikely scenarios," but added: "Eventheir remote possibility threatens trust in research andvaccines more than necessary, because public engagement on thisissue has been limited."