About three-quarters of those hospitalized for Covid-19 could become long haulers, according to a paper uploaded to the pre-print server medRxiv on August 14 without having yet been vetted by outside experts or accepted for publication. Researchers from the Academic Respiratory Unit of the North Bristol NHS Trust in the UK looked at 110 Covid-19 patients, whose illnesses required hospital stays for a median of five days between March 30 and June 3. Twelve weeks after patients were released from the hospital, 74% of them reported symptoms, including breathlessness and excessive fatigue. Despite these symptoms, however, 104 of the 110 patients in the study had normal basic blood test results, with just 12% showing an abnormal chest X-ray and 10% showing restrictive lung function through spirometry tests.