As flu season nears, people will be trying to distinguish between the symptoms of a common cold and flu and those of Covid-19.

The current Government guidance states anyone with symptoms of coronavirus can get a test, with the main effects listed as a high temperature, a new and continuous cough and a loss or change to your sense of smell or taste.

But Prime Minister Boris Johnson admitted there is not enough testing capacity after demand “massively accelerated” in recent weeks, with the UK seeing a spike in infection rates.

Professor Tim Spector, from King’s College London, who is leading the Covid Symptom Study app, said people are “getting it wrong” and are getting tests unnecessarily.

He told BBC 4 Radio’s Today programme on Thursday: “Most people’s chances are that they don’t have Covid, so we have to start thinking of ways to exclude it, rather than just going on this standard criteria that if you have any one of these (symptoms).”

He added that official guidelines worked well for people aged 18 to 65 but that there needed to be more flexibility for different age groups.

Here is what you need to know about symptoms of the common cold and Covid-19:

– Coughing

A new and continuous cough, usually dry, is one of the most common Covid symptoms.

The NHS describes it as coughing a lot for more than an hour, or three or more coughing episodes within 24 hours.

The Royal College of Paediatrics and Child Health (RCPCH) reported fever and cough as the most common symptoms for any child requiring hospital admission, with figures showing of 651 children admitted to hospital with Covid-19 in the UK, 70% had fever and 39% had a cough.

Emma Rubach, head of health advice at charities Asthma UK and the British Lung Foundation, said schools are sending children home with coughs related to colds, adding: “And so naturally, parents are concerned that their children who have a cough caused by asthma could be sent home as well.

“This would put further strain on the testing system,” she said, recommending parents to share their child’s personal asthma action plan with their school.

– High temperature

A high temperature is described by the NHS as feeling hot to touch on the chest or back.

While a high temperature is described as 38C or greater, people are not required to measure their temperature.

A high temperature, sometimes called a fever, is usually caused by your body fighting an infection which may not be Covid-19 and could be the flu.

It is usually accompanied by other symptoms including shivering (chills), sweating or warm, red skin.

– Loss or change to sense of smell or taste

Another common symptom of Covid-19, according to the NHS, is not being able to smell or taste anything, or things smell or taste different to normal.

Prof Spector said these symptoms were less common among older people and children.

A team of researchers across Europe, which included experts from the University of East Anglia, found those with Covid-19 could not detect bitter or sweet tastes.

In the small study involving 30 people, scientists said the loss of smell associated with Covid-19 infection is “much more profound” when compared with a bad cold or flu.

– Sneezing and runny or blocked nose

For those who are sneezing or have a runny or blocked nose, if no other symptoms develop it is likely to be a cold.

Prof Spector said a runny nose, congestion or sneezing is “a sign that you absolutely do not have Covid”.

The RCPCH advised that children with simple cold symptoms such as a runny nose or sore throats without fever should not be tested for Covid-19.

– Symptoms in different age groups

According to research from the Covid Symptom Study app, based on data from 198 children with positive tests and around 15,800 negative tests, academics at King’s College London listed fatigue, headache, fever, sore throat and loss of appetite as the most common symptoms among children.

Additionally, research from the app also found that one in six children who tested positive for Covid-19 also presented with an unusual skin rash.

Prof Spector said that of children who tested positive and had symptoms, around half did not have any of the three main signs listed by the NHS, while a third of the children in the research showed no symptoms.

The app’s data on adults showed fatigue, headache, loss of smell, persistent cough and sore throat were common among adults.

– Other symptoms

Prof Spector said around 80% of people across all age groups who use the symptom tracker app, which has more than four million users, reported severe headaches and tiredness in the first week of illness.

He said shortness of breath was less common among children.

The World Health Organisation (WHO) listed aches and pains, sore throat, diarrhoea, conjunctivitis, headache, loss of taste or smell, a rash on skin and discolouration of fingers or toes as less common symptoms of coronavirus.

However, some people who become infected do not develop any symptoms and do not feel unwell, the WHO said, and they can still transmit the virus to those around them.

Difficulty breathing or shortness of breath, chest pain or pressure and loss of speech or movement are the most serious symptoms, according to the WHO, which require immediate medical attention.

– How long it takes for symptoms to appear

A common cold usually passes within a week, with symptoms the same across all age groups, but can sometimes last longer in children.

According to the WHO, on average it takes five to six days from when someone is infected with coronavirus for symptoms to show, however it can take up to 14 days.