The most common signs of COVID-19 include a new, continuous cough, a high temperature and a loss or change to your sense of smell or taste. However, the notorious virus could cause two 'surprising' signs of an infection.
Utilising data from the COVID Symptom Study app, the researchers have gathered information on patients' most reported symptoms.
This evidence is based on the onset of symptoms in the first seven days.
The researchers commented on their investigation: "We have been busy researching what the early symptoms of COVID-19 really are.
"This information is essential to helping us all stop the spread of the virus in the coming months."
To explain, the researchers noted how spotting signs of COVID-19 much sooner can enable people to self-isolate more quickly.
They added this could "stop the accidental spread of the virus", when people may otherwise go about their days unwittingly carrying the disease.
Described as the "dark horses of COVID symptoms", a headache and fatigue have been identified as early warning signs.
"Our data shows that the most commonly experienced early symptoms are actually headache (82 per cent) and fatigue (72 per cent)," the researchers confirmed.
They added this was true of cases "for all age groups", with "only nine percent of COVID-positive adults" not experiencing these signs.
However, the researchers have warned the public that these two symptoms alone aren't indicative of the disease.
"While headache and fatigue are commonly found in people who have COVID, having either or both of those symptoms alone is unlikely to be COVID."
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The researchers continued to say that "40 percent of all age groups reported having a fever in the first seven days".
A fever, alongside coughing fits and a loss or change to your sense of smell or taste are still key symptoms to be aware of.
The NHS clarified that a new, continuous cough means "coughing a lot for more than an hour, or three or more coughing episodes in 24 hours".
For those people who may already suffer from a chronic cough from another condition, a COVID cough would be "worse than usual".
The NHS confirmed "most people with coronavirus have at least one of these symptoms" – meaning fever, cough, or loss or change to sense of smell or taste.
The researchers of King's College London echoed this advice by stating people with the "classic symptoms should certainly see a COVID test".
Delving into their statistics, they also found certain signs of COVID that affect people over the age of 65.
It's reported confusion, disorientation and severe shortness of breath appear in the early stages of infection.
The investigation into early warning signs of the disease are still ongoing.
As more people download and utilise the app, the researchers will be able to gain a more clear picture of the threat we are facing.
When new findings arise, researchers from King's College London will continue to update the public.
If you'd like to be part of the fight against COVID, download the free NHS COVID-19 app today.