Boris Johnson has announced that NHS England’s contact-tracing system aimed at containing the spread of coronavirus will go live on Thursday.

– How will the NHS Test and Trace system work?

If you are concerned you have coronavirus, you can order a test by dialling 119 or going to NHS.UK/coronavirus – that begins the whole process.

If your test comes back positive, you will be asked to provide details of people you have been in close contact with – defined as being within two metres for more than 15 minutes without protective equipment.

Those people who have been in contact with you will be contacted by NHS Test and Trace and told to isolate for 14 days, even if they have no symptoms.

Existing rules will continue to apply, which means that anyone who develops symptoms should isolate for seven days and the remaining members of their household for 14 days.

– How many people are involved in the system?

Around 50,000 – a mixture of testing staff and contact tracers includings around 7,000 clinicians.

– How long will people need to wait for the results of a test?

The Government does not expect all test results will be made available within 24 hours, but officials are focusing on the scheme of the process from start to finish – from the test being ordered to contacts being traced.

– How will the system be enforced?

Initially the system will rely on people acting responsibly and following the guidance if they are told to isolate themselves.

But if the system of voluntary compliance does not work, ministers will be able to bring in tougher measures which could see people potentially subjected to spot checks and fined if they are not following the rules.

– What if I’ve broken lockdown rules and mingled with people I should not have – should I tell the NHS when I reveal my contacts?

The call to NHS Test and Trace will be confidential and is aimed at ensuring that potential cases are tracked down, rather than finding out if people have flouted the social-distancing rules.

What if I’ve already tested positive for Covid-19 and recovered – will I need to isolate again if contacted?

You must still isolate as instructed because it is not yet know whether having the disease in the past means you are now immune, or whether you can still act as a carrier who can infect others.