The Government is being urged to update the list of "classic" Covid symptoms as sneezing is now among the most common signs.
Professor Tim Spector, co-founder of the ZOE Covid symptom study, said recent data showed the "classic" signs of having the virus have now changed with a headache, runny nose and sore throat more common.
The study is the world's largest ongoing study into the virus with more than four million people across the globe logging information on symptoms, testing and vaccines.
All participants have tested positive for the virus, Sky News reports.
Prof Spector said a headache was now at the top of the list of most common symptoms, with 60% of people who experienced one testing positive for the virus.
A runny nose and sore throat were also in the top three and sneezing is listed at number four, though it can be confused with hayfever.
A persistent cough was the only original "classic" symptom to make the top five.
The two other "classic" signs of fever and loss of smell and taste - coming in at number seven and nine respectively.
Prof Spector said: "It is about time the government, after a year and a half, change the list of classic symptoms.
"We do need a much broader flexible approach to this as the virus changes and the populations change."
The new data shows the current "classic" list may mean undiagnosed people could be unknowingly spreading the virus.
Prof Spector said: “Covid is acting differently now it’s more like a cold in this younger population and people aren’t realising this, and people might think they’ve got some sort of seasonal cold and they still go out to parties and they might spread it around.”
He also warned on Wednesday that the current wave of coronavirus infections "should be peaking around 10 to 14 days' time".
He said: "We are still seeing rates increasing, around about 15,000 cases a day is our estimate based on your reports, but the good news is that this isn't going up as fast as it was.
"I would be predicting that this should be peaking around 10 to 14 days' time and then start to fall, so that by four weeks we are much below the level we are now, and at something much more manageable.
"That's if all goes well," he added.
