London, July 1 : With 69 per cent people reporting headache prior to a Covid infection, it has become the leading symptom of the disease, according to a study. Researchers from King's College London analysed data from the ZOE Covid Symptom study app and found headache as one of the earlier signs of the condition. It is also "more common" than the other classic Covid symptoms like fever, cough and loss or change to taste and smell, Express.co.uk reported. The study reported that some Covid patients could be left with a headache for much longer than the initial infection as this sign is also a characteristic for long Covid. "Our data shows that these headaches often come and go, but thankfully they gradually reduce over time," the study said. Although this painful symptom seems to be less common in children, coronavirus headaches tend to be seen across all age groups. Yet "headaches are very common", because of staring at screens for too long. "So, although many people with Covid-19 experience headaches, most people with a headache will not have Covid-19," the study noted, adding that headache with increased fatigue and loss of smell can signal Covid. Other signs that could also point to the direction of the virus include a sore throat, fever, unusual muscle pain, and persistent cough and dizziness, the report said. Launched in March 2020, the ZOE Covid Study app is used by participants who regularly report on their health and symptoms and whether they have tested positive for the virus. /IANS