With symptoms of coronavirus varying widely from person to person, it's very difficult to identify if people have had the virus unless they were officially tested.
Some have been entirely asymptomatic, meaning they show no signs of Covid-19, but have tested positive, while others can experience symptoms ranging from mild to those which require emergency care.
Many people who have experienced mild symptoms, including a fever, fatigue, dry cough, shortness of breath, and loss of taste and smell, but haven't been tested may suspect they have already had coronavirus.
The problem is the milder symptoms can mirror those experienced with more common illnesses, like a cold, making it difficult to diagnose.
Dr William Hillmann, an associate inpatient physician director at Massachusetts General Hospital, explains that the only way to tell if someone has already had coronavirus would be with an antibody test.
It would allow experts to check blood samples for antibodies against the virus, but these are still being developed and are not yet in widespread clinical use.
Dr Hillmann told The Guardian : "I, and I think many others, are anxiously awaiting for those to become available."
He explains that even those who have had coronavirus with no symptoms are still contagious for a period of time, but 'we just don't know for how long at this point'.
People who may believe they have coronavirus should act no differently to those who don't, for the safety of themselves and others around them.
Dr Hillmann says: "Since there’s no real way to know at this point who might have had it, unless you’re symptomatic, you get a swab and are definitively diagnosed with it, I would just act as if you hadn’t had it.
"Keep doing all of those things that we all should be doing at this point: social distancing and hand hygiene."
Although those who have had coronavirus are expected to build an immunity to it, at least for a short period of time, at this point it still remains unclear if the same person can catch it twice.
On the issue of whether you should tell people you've come into contact with that you suspect you have had coronavirus, even if it may have been something more common like a cold, Dr Hillmann says: "It’s up to every individual about what they feel is right."
But adds: "If you were symptomatic at one point but were not tested, and you were in close contact with somebody, I think you should tell them."
Click here to see the full NHS guidelines on coronavirus and how to stay safe.
