The process of setting up a human infection study is long and rigorous – taking up to a year and involving many stages to meet high safety and ethical standards. Several key things need to be in place before they can begin, including the development of a suitable challenge agent (which is the dose of the virus that is given to volunteers), volunteer recruitment, site preparation, and having an effective treatment that is known to work. A Covid-19 human infection study will follow a similar process, but there will be some differences.
One difference is that Covid-19 human infection studies are being considered by some governments and funders in the absence of an effective treatment. Even though these studies would be subject to even stricter regulation and monitoring, Wellcome will only support a Covid-19 study if and when an effective treatment is found.
Volunteers normally take part in human infection studies for around 15 days. This will be the same for Covid-19 studies, but the follow-up, at least for the first few studies, will be much longer to gain information on the duration of antibody response and to confirm there are no long-term side effects.
Another difference is that, compared with other studies such as for malaria, Covid-19 studies are only likely to take place in high-income settings – like the UK and the US – where facilities can meet the stricter quarantine standards required. Dedicated quarantine facilities will need to be upgraded for Covid-19 studies, for example to allow for controlled air flow. Suitable Covid-19 quarantine facilities will usually be isolation wards attached to hospitals.
The profile of the volunteers who take part may also be different. To maximise safety, volunteers will not include people who are at risk for severe cases of Covid-19, such as people:
- over the age of 50
- with pre-existing health conditions (for example, diabetes)
- with respiratory problems
- from a Black, Asian and minority ethnic population.
Traditionally, studies involve volunteers who have no antibodies to the pathogen they are going to be infected with. However, Covid-19 studies may also include volunteers with a small level of antibodies to look at how long immunity against re-infection lasts.