COVID-19 Challenge Study (COV-CHIM 01)

What is the purpose of this study and why participate?

SARS-CoV-2 is the virus responsible for COVID-19 disease. Recent roll out of licensed vaccines is a positive step towards fighting COVID-19. However, we don’t know how long protection after COVID-19 infection lasts and why some people can get infected a second time.

We would like to develop a safe human infection model (challenge model) where volunteers who have previously had COVID-19 are re-exposed to the SARS-CoV-2 virus in a controlled manner. Information gained from this initial study will enable future research that may help us understand what kind of immune response stops people from being re-infected with COVID-19 and the impact of the virus on the immune system. This may eventually help with the development of better COVID 19 vaccines and treatments and might help develop a test that tells people if they are protected from the virus.

To do this, we need to establish the lowest dose of virus required to cause re-infection (a positive throat and nose swab) but with the aim of causing minimal or no symptoms. For safety purposes, we will have a very strict selection criteria for who can take part and will perform close monitoring of participants (including an inpatient quarantine stay).


Am I eligible to participate?

What does the trial involve?

The study will consist of 3 phases:


You will be in the study for 12 months from enrolment (Day of administration of the virus) to the last clinic appointment.


We plan to recruit up to 44 participants initially (possibly up to 64) into two groups:


Group 1: Safety and dose finding group where each dose will be tested in 8 participants

We will start by testing the lowest dose of the virus and then test higher doses if needed. An independent Data Safety Monitoring Board will be monitoring the study and will tell us to continue, increase or decrease doses. You will be informed which dose group and/or cohort you are assigned to. You would only receive the virus once and cannot choose which dose group or cohort you are in.

Group 2: Safety and dose confirmation in up to 20 participants initially (possibly up to 40)

Once an optimal dose of the virus has been selected in the dose finding group (group 1), we will enrol up to 20 participants in group 2 using this dose. The findings from these first 20 participants will be carefully reviewed and if needed (to achieve statistical significance of results generated), a further group of up to 20 participants may be enrolled.
For full details on the groups and of all visits, please read the participant information sheet and Quarantine information sheet .

What are the advantages of taking part?

You will not gain any direct benefit from the study, however, during pre-study assessment you will get information about your health including results from a medical examination, blood tests, urine tests, chest x-ray, ECG (heart trace) and lung function tests. You may also get information about your health from the MRI heart scan (magnetic resonance imaging) or echocardiogram (ultrasound of heart). However, these assessments are not carried out for diagnostic purposes and should not be considered a substitute for a doctor’s visit.

We hope that the information we gather from this study will lead to a test of protection against COVID-19 and better vaccines/treatments that could help many people around the world. There is a chance you could develop or further boost antibodies and T cells (the two arms of the immune system that fight infection) against COVID-19 but we don’t know if you will develop antibodies or T cells and whether they would protect you against further COVID-19 infection.
You will also receive compensation for your time, inconvenience and travel expenses of at least £4995 for full study participation.

Can I take part in the study after receiving a COVID-19 vaccine?

You may take part in this study if you have received a COVID-19 vaccine. However, to avoid confusing potential vaccine side effects and COVID-19 side effects we ask that you wait for 21 days after vaccination (1st dose or booster doses) before enrolment into the study.

Are there any risks from taking part in the study?

This virus is currently causing a world-wide pandemic of respiratory disease ranging from asymptomatic or mild illness to severe respiratory disease that may also affect other parts of the body. Humans have only experienced infections with this strain of virus since late 2019, and the full range of symptoms or disease caused by COVID-19 is still being investigated. Therefore, at present it is not possible to predict accurately and completely the risks to you from participating in this study.

Some people when infected with COVID-19 experience no symptoms at all. More severe cases of COVID-19 disease are usually seen in the elderly (over 65 years of age) and those with pre-existing medical conditions (such as diabetes).

However, severe COVID-19 disease can rarely occur in young, healthy adults. In England up to 6th November 2020, 95 adults between the ages of 18-30 had died from COVID-19 from the total number of deaths with COVID-19 recorded at over 49,000 by this date. During the pandemic, it is therefore estimated that 1-2 people per 100,000 aged 18-30 have died (although, most have had other health conditions before developing COVID-19). It has also been estimated that 1 in 200 people aged 20-29 with COVID-19 needed to go into hospital. The factors that might increase the risk of such events in

young persons are not fully known and therefore may not be detected in the screening process prior to entering the study.

Please refer to the information sheet and Quarantine information sheet for full details of procedures and potential risks.


What will happen if I don’t want to carry on with the study?

Participation is voluntary and you are free to change your mind and withdraw at any time. However if you decide to withdraw your consent and `leave the study' during the quarantine phase, you will be very strongly encouraged to remain in the Quarantine unit until you are no longer contagious. This is for both your safety and that of others whom you could infect as a contact. In this situation, we would continue to optionally offer you all procedures considered important for safety purposes by the study team but would stop any research procedures.

If you withdraw from the study, any samples and data collected before your withdrawal will be used/stored unless you specifically request otherwise. However, if any of your anonymised data has been incorporated into the study, it will not be withdrawn or erased in order to comply with our legal obligations and to maintain the scientific integrity of the study.

Please refer to the  information sheet and Quarantine information sheet for full details of procedures and potential risks.

What’s next?

Please read the full participant information sheet here and Quarantine information sheet.

If you are interested in taking part, please click here to apply via the pre-screening questionnaire.