It can be hard to tell the difference between Covid-19 and the common cold without a test.
The typical symptoms of the common cold like headache, runny nose and sore throat, are also some of the primary indicators of Covid.
On December 23, researchers behind the ZOE Covid Study warned that anyone with a runny nose, headache or sore throat was likely to have the Omicron variant.
"For most people, an Omicron positive case will feel much more like the common cold, starting with a sore throat, runny nose and a headache. You only need to ask a friend who has recently tested positive to find this out. We need to change public messaging urgently to save lives." Professor Tim Spector, founder ZOE app, via BBC.
According to the ZOE Covid Study, headaches are one of the earliest signs of Covid and are more common than cough, fever and loss of smell.
The ZOE study also found that nearly 60% of people with Covid reported a runny nose, making it the second most common symptom.
However, the study warns that it is hard to call a runny nose a definitive sign of Covid as it is so common, particularly during winter.
According to ZOE, about half of people with Covid report a sore throat.
Loss of smell continues to be the most common indicator of Covid, regardless of age, sex or severity of the infection.
The ZOE study found that while a persistent cough is one of the 3 main symptoms of Covid, only around 4 out of 10 people with Covid experience it.
'The Independent' recommends that anyone with these symptoms should self-isolate and get a Covid test as soon as possible.