LONDON - Alex Greer says he'd rather put himself directly in the path of the coronavirus than get blindsided by the disease after an evening at the pub or with friends. It's a scenario that could soon become a reality.
Britain is moving closer to carrying out studies that would intentionally infect healthy people with the virus to help researchers in their quest for Covid-19 vaccines, and thousands of volunteers like Greer, a chemistry student at Durham University in northeast England, are ready to go.
Open Orphan Plc, parent of human challenge trial specialist hVivo, has said it's in talks with potential customers including the UK to conduct tests of Covid shots.
Such studies may help speed development of vaccines and give scientists new insights into a disease that has spread to more than 37 million people globally, but would expose participants to a threat for which there's no cure.
Numerous questions about the virus - which volunteers would likely have sprayed into their noses - remain unanswered. Even young people could face dangers.
"I can't lie and say it doesn't cross my mind," said Greer, 20.
"The long-term consequences of Covid aren't fully researched yet and that does need to be taken into account. But I think the potential successes of the trials outweigh that small risk to myself."
Despite recent strides in treating Covid-19, experts disagree on whether challenge trials are justifiable.
One uncertainty is why some young and otherwise healthy people end up with complications months after experiencing mild symptoms, according to Seema Shah, a bioethicist at Lurie Children's Hospital of Chicago and Northwestern University.
CROSSING A LINE
"This would really cross a line that people have drawn in terms of when it's ethically acceptable to do challenge studies," she said.
"In the past, it's been about diseases that we know a lot more about. We're still learning so much about Covid-19."
Companies such as AstraZeneca Plc - the University of Oxford's partner in an experimental coronavirus vaccine - suggested earlier this year that declining infection rates could make it harder to do conventional tests that wait for people to catch the virus naturally in the wider community.
Yet Covid continues spreading, allowing a number of projects to sprint into the final stage of clinical trials.
Pfizer Inc. and AstraZeneca say they have no plans to do challenge studies. Other vaccine makers like Johnson & Johnson are eyeing them cautiously.
The US National Institute of Allergy and Infectious Diseases, partner of biotech company Moderna Inc., has started manufacturing a strain of the virus that could be used for challenge studies and is investigating technical and ethical considerations.
"We will only go in this direction if the ethical, the medical and the safety parametres are clear," said Thomas Lingelbach, chief executive officer of Valneva SE, a French company working on another experimental Covid shot.
The idea is gaining momentum. 1DaySooner, a group that advocates on behalf of people who want to join challenge studies, says it has attracted more than 38,000 volunteers.
UK studies would likely be the first such tests in the world for Covid-19.
"I'm sure it will happen," said Robin Shattock, an infectious disease expert at Imperial College London.
"The difficulty is to know what it actually will achieve and whether it will make anything quicker."
Various forms of human challenge studies have been used for centuries, but proper practices and guidance for ethics and safety were only adopted about 50 years ago.
The approach was key to vaccine development for diseases such as cholera, malaria and typhoid.
No deaths have been recorded from challenge trials in recent decades, research shows, and studies have been performed safely in tens of thousands of consenting volunteers.
Unlike Covid-19, however, many of the diseases targeted by these trials had well established treatments.
Challenge studies could play an important role as scientists look to build on the first generation of Covid-19 inoculations, according to Northwestern's Shah.
They might offer a way to compare efficacy, allowing the best prospects to advance in larger studies, and tackle questions such as the persistence of vaccine-induced immunity.
UK support, along with therapies like Gilead Sciences Inc.'s remdesivir for patients who get sick, would provide a boost for the campaign.
Eli Lilly & Co. and Regeneron Pharmaceuticals Inc. last week asked US regulators for emergency-use authorisations for their antibody treatments, and many other companies are advancing with potential weapons as well.
"If the UK can be involved in human challenge trials, we'll be leading in this area of science," said Jennifer Wright, a 29-year-old volunteer who's pursuing her PhD in physics at the University of Glasgow.
"It should be the countries with the most money who lead these kinds of efforts, because we are the ones who presumably won't suffer as much."
The issue is heating up as the virus advances and governments push for a way out of worsening economic damage to travel, tourism, retail and many other industries.
The risks would be minimised as much as possible by selecting younger people who don't have underlying health conditions, and keeping volunteers under constant observation, according to proponents.
"There's pretty clear evidence across the world it's young people who are least susceptible to severe disease," said Adrian Hill, director of Oxford's Jenner Institute.
"Everyone would agree that it would be nice to have something more than remdesivir, but it's not even clear if you would need remdesivir."
Such studies in the US wouldn't replace large final-stage trials, according to the Niaid. Data from ongoing conventional trials will be available toward the end of 2020 and will be used to assess future challenge studies "should they be needed and deemed safe and ethical to employ," the agency said in an email.
Any UK plan would still need to overcome hurdles including approval from regulators and an independent ethics committee.
"Given the state we are in with respect to the epidemic and the urgent need for multiple efficacious vaccines, I think there remains a very compelling case for proceeding," said Peter Smith, an epidemiologist at the London School of Hygiene & Tropical Medicine.
The main question is whether the studies would clearly "make a big difference," said Northwestern's Shah.
"I just don't know yet whether there's a solid rationale for moving forward."