More than 21,700 people have volunteered to be exposed to the coronavirus to speed up vaccine development.
By Saturday, a total 21,729 people from 102 countries had signed up on 1DaySooner for the Covid-19 human challenge trial, or HCT.
Human challenge trials deliberately expose participants to infection, in order to study diseases and test vaccines or treatments, explained the site.
Such trials have been used for influenza, malaria, typhoid, dengue fever, and cholera.
Researchers are exploring whether human challenge trials could speed up the development of a vaccine for COVID-19, saving thousands or even millions of lives.
Even though no HCT is planned.
But 1DaySooner, a team of 10 grassroot researchers and scientists, is recruiting volunteers and pre-qualifying them should the need for a HCT arise.
Why does it matter?
No one is yet certain how the ongoing coronavirus pandemic might play out. There are plenty of uncertainties. There is a lot of talk about “flattening the curve”.
And only changes in attitudes and social behaviours—from sheltering in place and hygiene to social distancing and protective covering—will affect eventual spread.
Beyond mortalities and morbidities, the impact of the pandemic on economy and livelihood are still being felt.
There’s no definitive drug for treatment of Covid-19 yet. What’s certain is that a vaccine will be needed to contain it.
The rub is that vaccines take long to produce—and it may up to 18 months from now before candidate vaccines are ready for widespread human use.
Before that they must undergo extensive trials in humans. And Covid-19 may have petered out by then.
Human challenge trials shorten the time before vaccines are ready for use.
1DaySooner plots a projection of the impact of vaccines, based on the number of people getting Covid-19 and the number of people vaccines could stop from dying.
Suppose one in six people in the world gets Covid-19 each year, and a vaccine can prevent one in five of them from dying, speeding up vaccine development by:
- 1 day saves 7,120 lives
- 1 week saves 55,000 lives
- 1 month saves 220,000 lives
- 3 months saves nearly 660,000 lives
A stretch of time
A vaccine goes through multiple stages of testing. Because billions of people could receive a Covid-19 vaccine, its safety and efficacy need to be assured.
A candidate vaccine goes through first test on animals.
That’s to see if it is safe and whether it provokes an immune response—able to trigger the body’s immune system to produce antibodies that fight the virus.
It is then tested on a small group of human volunteers for safety and immune response. That’s a Phase 1 trial. Usually one group is given a placebo, a second group is given an attenuated version of the virus, before both groups are exposed to the virus. They may also return to their normal lives so the effect of the vaccine in the real world is noted.
If the results are good, it goes into Phase 2 trial, using a larger and more representative population of hundreds of volunteers.
Phase 3 takes the longest time. Researchers at this point evaluate the effectiveness of the vaccines using thousands of participants.
They look at differences in infection risks and side effects between participants given the vaccine and those given a placebo.
The target is to find a vaccine that both reduces the risk of infection and causes no side effects. It is the final step before a vaccine is deemed safe enough for widespread use.
With coronavirus, people are taking special steps to stay safe and fewer people may be interested in volunteering in a vaccine trial.
If live coronavirus human challenge trials are held, willing participants would receive the vaccine candidate or placebo and, after some time for the vaccine to take effect, be deliberately exposed to live coronavirus.
Since exposure to the virus is guaranteed in HCTs, it may be possible to judge a vaccine candidate’s efficacy more quickly and with far fewer participants than a standard Phase III trial.
It may not provide sufficient basis for licensing a vaccine but it allows researchers weed out candidate vaccines that are not worth the effort and promote those that are more promising—in conjunction with Phase 3 trials.
A study evaluating human use cases of HCT for accelerating development of a Covid-19 vaccine presents scenarios where HCT could be useful: evaluating efficacy, considering protection offered by candidate vaccines and improving understanding of the biological mechanism that aids the disease and the human immune system.
“We conclude that, while currently limited in their application, there are scenarios in which HCTs would be vastly beneficial and, thus, the option of using HCTs to accelerate COVID-19 vaccine development should be preserved,” the researchers wrote in their article on OSF PrePrints.
Why sign up?
The 21,729 signed up so far have to give their justification for volunteering. One of them is a Nairobi-based journalist.
“I am a journalist who reports in and on the developing world, and participating would both allow me to perhaps contribute in a small way to helping the sorts of people I report on,” they wrote.
A US resident in Saint Paul, Minnesota said, “Times like these call for people who are able to be brave and put themselves forward for the greater good of society—this may be defining period of my lifetime.”
Another volunteer from Surrey in the UK: “I’m a young, healthy student and want to help develop a safe vaccine quickly, and am happy to volunteer to be part of this process. The importance of this outweighs personal risks in my opinion.”
An American parent in their 50s from Austin, Texas, said, “I am older – 52, my kids are grown and I feel like if I can help save people who are not in the same position then I should do it.”
Yet another has four reasons for volunteering from Portland, Oregon in the US: “1) I’m a scientist. 2) I’m a mother. 3) I have living parents and grandparents. 4) I strongly believe in vaccination for public health and the power of herd immunity.”
HCTs are risky for volunteers but the organisers say they are minimising the risks, specifically for Covid-19, by recruiting only young people aged 20 to 45 and with no underlying health conditions with lower chances of becoming seriously unwell with the disease.
Volunteering is on an “expression of interest”, organisers of the human challenge trial make clear.
“There will be multiple stages of registration and pre-qualification before selected volunteers can formally consent to participating in a human challenge trial (if one is ultimately approved and conducted).”
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