Women are more likely to spot early signs of Covid than men because they are better at noticing changes in their body, researchers believe.
The study, which looked at data from the Zoe Covid Symptom Study app, found that men were more likely to report shortness of breath, fatigue, chills and fever following infection, while women were more likely to notice loss of smell, chest pain and a persistent cough.
Researchers believe that although the differences could be biological, they may also be caused by women being better at recognising more subtle symptoms. While loss of smell or a cough may be easy to ignore, it is harder to brush off chills or a fever, which may be a later stage of the virus.
Claire Steves, the study’s lead author and a reader at King’s, said: "It’s important people know the earliest symptoms are wide-ranging and may look different for each member of a family or household.
"We’re not the first study to show a difference in symptom reporting between men and women. Women report more symptoms overall than men, and women might be more sensitive to a wide range of symptoms. They are more likely to recognise symptoms within themselves.
"The point is we found a slightly different structure of symptoms between women and men, which means they may well need different symptoms to prompt them to get a test.
"We’ve always been a little bit concerned there were only three core symptoms, and now that testing is widely available we should encourage people to get tested even if they have symptoms that aren’t core."
Early Covid symptoms: Men vs women
Currently, the Government advises getting tested for Covid if suffering from a persistent cough, a high temperature or a change in taste or smell.
But the King’s team have found 18 different symptoms associated with the virus and say the earliest are loss of smell, chest pain, persistent cough, abdominal pain, blisters on the feet, eye soreness and unusual muscle pain. The researchers found 80 per cent of cases could be detected using those early symptoms.
They also found age differences in reported symptoms. Those aged 60 and above were more likely to report diarrhoea, but loss of smell was less common among this age group and was not relevant at all for the over-80s.
Likewise, fever was found not to be an early feature of Covid in any age group despite being a known symptom, suggesting people have already had the disease for some time already by the time they develop a high temperature.
Dr Liane dos Santos Canas, of King’s College London, said: "Currently in the UK, only a few symptoms are used to recommend self-isolation and further testing. Using a larger number of symptoms and only after a few days of being unwell, using artificial intelligence, we can better detect Covid-19 positive cases.
"We hope such a method is used to encourage more people to get tested as early as possible to minimise the risk of spread."
The findings, published in the journal Lancet Digital Health, are based on modelling using artificial intelligence to predict early signs of infection. The modelling study was used on the original strain of the virus, which first appeared in Wuhan, China, as well as the alpha variant.
Researchers said the findings suggested the symptoms of the delta variant and subsequent variants would also differ across population groups.
Dr Marc Modat, senior lecturer at King’s College London, said: "As part of our study, we have been able to identify that the profile of symptoms due to Covid-19 differs from one group to another. This suggests that the criteria to encourage people to get tested should be personalised using individuals’ information such as age.
"Alternatively, a larger set of symptoms could be considered, so the different manifestations of the disease across different groups are taken into account."