LONDON: British researchers on Tuesday (Oct 20) said they hope to expose healthy volunteers to the virus that causes COVID-19 in a groundbreaking study to discover the amount needed for people to become infected.
The Human Challenge Programme – a partnership that includes Imperial College London – hopes the work will ultimately help to "reduce the spread of the coronavirus, mitigate its impact and reduce deaths".
In what researchers called a world first, the opening stage of the project will examine the possibility of exposing healthy volunteers to the SARS-CoV-2 coronavirus.
They aim to recruit volunteers between the ages of 18 and 30 with no underlying health conditions such as heart disease, diabetes or obesity.
"In this initial phase, the aim will be to discover the smallest amount of virus it takes to cause a person to develop COVID-19," Imperial College said in a statement.
This type of research, known as a human challenge study, is used infrequently because some consider the risk involved in infecting otherwise healthy individuals to be unethical.
But researchers racing to combat COVID-19 say that risk is warranted because such studies have the potential to quickly identify the most effective vaccines and help control a disease that has killed more than 1.1 million people worldwide.
"Deliberately infecting volunteers with a known human pathogen is never undertaken lightly," said Professor Peter Openshaw, co-investigator on the study.
"However, such studies are enormously informative about a disease, even one so well studied as COVID-19."
Human challenge studies have been previously used to develop vaccines for diseases including typhoid, cholera and malaria.
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"NUMBER ONE PRIORITY IS SAFETY"
In the first phase of the UK challenge study, researchers will expose 90 paid volunteers to the virus using nasal drops in an effort to determine the smallest level of exposure needed to cause COVID-19.
The research will be conducted at the Royal Free Hospital in London, which has a specially designed area to contain the disease. Volunteers will be monitored for at least a year to ensure they do not suffer any long-term effects.
"The great advantage of these volunteer studies is that we can look at each volunteer very carefully not only during the infection but also prior to infection, and we can work out exactly what's going on at every stage," Openshaw told BBC Radio 4 on Tuesday.
Ultimately, the same model will be used to test the effectiveness of potential vaccines by exposing volunteers to the virus after they have received one of the candidate vaccines.
Because the study deliberately infects the volunteers, "it should be possible for scientists to begin to establish efficacy very quickly, by testing if those who have had a vaccine are less likely to become infected with the virus", explained the researchers.
"Our number one priority is the safety of the volunteers," said Chris Chiu, from Imperial's department of infectious disease.
"No study is completely risk free, but the Human Challenge Programme partners will be working hard to ensure we make the risks as low as we possibly can."
"The UK's experience and expertise in human challenge trials as well as in wider COVID-19 science will help us tackle the pandemic, benefiting people in the UK and worldwide," he added.
But Jonathan Ball, professor of molecular virology at the University of Nottingham, warned that safety concerns may limit what researchers can learn from the study.
"Any studies involving the novel coronavirus will focus on those most likely to experience a mild infection – young healthy volunteers," he said in a press release from the Science Media Centre.
"Yet the people we need to protect against serious disease are more vulnerable elderly people, so what we learn from challenge studies might have limited wider relevance."
The study is expected to begin early next year, said the research team from the partnership, which also includes the government, a clinical company and a hospital.
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Governments around the world are funding efforts to develop a vaccine in hopes of ending the pandemic that has pummelled the international economy, shutting businesses and putting millions of people out of work.
Forty-six potential vaccines are already in human testing, with 11 of them in late-stage trials – several expected to report results later this year or in early 2021.
"I don't think many people think that what we're doing as scientists is searching for a silver bullet," said Michael Jacobs, a consultant in infectious diseases at the Royal Free London NHS Foundation Trust who will take part in the research.
"We're going to need a whole raft of interventions in order to control this pandemic."
Tens of thousands of volunteers around the world have already signed up to participate in more traditional trials of COVID-19 vaccines. Critics of challenge studies question the need to expose healthy people to the virus when the disease remains widespread and vaccine development is moving quickly.
Kate Bingham, chair of the government's Vaccine Taskforce, which is tasked with promoting development of a vaccine for COVID-19, said the project will improve understanding of the virus and help scientists make decisions about research.
"There is much we can learn in terms of immunity, the length of vaccine protection and reinfection," she said in a statement.
Challenge studies are typically used to test vaccines against mild infections to avoid exposing volunteers to a serious illness if the vaccine does not work.
While the coronavirus causes only mild or moderate symptoms in most people and seems to be especially mild in young, healthy individuals, the long-term effects of the disease are not well understood, and there have been reports of lingering problems in the heart and other organs even in those who do not ever feel sick.
"I WANT THIS PANDEMIC TO BE OVER"
In the US, the National Institutes of Health (NIH) has downplayed the need for challenge studies given the speed with which vaccines are being developed, but it has taken preliminary steps to prepare for such research in case the approach eventually is required.
Those steps include examining the ethics of a challenge study, and funding research to create lab-grown virus strains that potentially could be used.
But even if they are needed, "human challenge trials would not replace Phase 3 trials" of COVID-19 vaccines, according to a September statement from NIH that called the standard, rigorous studies its priority.
In July, the NIH's vaccine working group published a paper in the New England Journal of Medicine pointing out the risks of doing a challenge study with a virus that so far has no good treatment and is wildly unpredictable, occasionally killing even some young, otherwise healthy people.
But 1Day Sooner, which advocates for COVID-19 challenge trial volunteers, praised the decision and called on the government to build a testing centre.
"We are glad the UK government is embracing the altruism of the thousands of our British volunteers who want these studies," the group said in a statement.
"Challenge trials will be key to making multiple safe and effective COVID-19 vaccines available for the whole world, including those in low-income countries bearing the brunt of this pandemic."
Danica Marcos, 22, a recent university graduate now doing volunteer work with homeless people, is hoping to take part.
"So many people (are) struggling right now, and I want this pandemic to be over," she told the Associated Press.
"Every day that goes on, more cases are going on, more people are dying. And if this vaccine trial could mean that this period of trauma for the whole world will be over sooner, I want to help. I want to be a part of that."