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.