Harvard researchers have compiled a list of clues to help clinicians distinguish between early COVID-19 and other infections with similar symptoms. 

Early differentiation is crucial in the absence of universal and reliable point-of-care diagnostic testing, says lead author Pieter Cohen, M.D. Based on data from more than 1,000 patients who visited an outpatient clinic for respiratory illness since March, he and his colleagues have found the following: 

  • Fever is not a reliable indicator. If present, it may manifest only with mild elevations in temperature.
  • COVID-19 may begin with various permutations of cough without fever, sore throat, diarrhea, abdominal pain, headache, body aches, back pain and fatigue
  • It can also present with severe body aches and exhaustion.
  • A reliable early hint is loss of the sense of smell in the first days of disease onset.
  • In serious COVID-19, shortness of breath is a critical differentiator from other common illnesses.
  • Almost no one develops shortness of breath, a cardinal sign of the illness, in the first day or two of disease onset.
  • Shortness of breath can appear four or more days after onset of other symptoms.
  • The first days after shortness of breath begins are a critical period that requires close and frequent monitoring of patients by telemedicine visits or in-person exams.
  • The most critical variable to monitor is how the shortness of breath changes over time. Oxygen saturation levels can also be a valuable clue. Blood oxygen levels can drop precipitously with exertion, even in previously healthy people.
  • A small number of people may never develop shortness of breath. Instead, they may have other symptoms of low oxygen levels, including dizziness or falling.
  • Anxiety is common among patients with viral symptoms suggestive of COVID-19, and anxiety can also induce shortness of breath.

How to tell the difference between COVID-19 shortness of breath and anxiety:

  • Anxiety-induced shortness of breath occurs rapidly, while COVID-19 shortness of breath tends to develop gradually over a few days.
  • Patients whose shortness of breath is caused by anxiety often say the sensation occurs during rest or while trying to fall asleep, and an inability to get enough air into their lungs. In contrast, shortness of breath induced by COVID-19-related drops in oxygen gets worse with physical exertion.
  • Anxiety-related shortness of breath does not cause drops in blood oxygen level

Full findings will be published in Mayo Clinic Proceedings, and are currently available as a pre-proof.