Fatigue, headache, sore throat and diarrhoea should be added to the existing three symptoms which trigger a Covid test, researchers have suggested. Currently, government guidance states anyone with a cough, fever or loss of smell or taste qualifies. Testing for the additional four symptoms could pick up 40% more cases, according to King’s College London and the Zoe Symptom Study app. The government said an expert scientific group keeps the virus symptoms under review and “the main symptoms have been carefully selected to capture those most likely to have Covid-19, while not capturing a great number of people who do not”.