Researchers in the United Kingdom have identified six "types" of COVID-19 illness, each with a particular cluster of symptoms.
Researchers analyzed data from the COVID Symptom Study application. They used a machine-learning algorithm to examine data from about 1,600 app users in the U.K. and U.S. with confirmed COVID-19 who had regularly logged their symptoms using the app in March and April. They then tested the algorithm by running it on a second dataset of 1,000 app users in the U.K., U.S. and Sweden, who had logged their symptoms in May.
The analysis, which has not been peer-reviewed, revealed six specific groupings of symptoms emerging at different timepoints during the progression of the illness. They are:
1. Flu-like with no fever: Headache, loss of smell, muscle pains, cough, sore throat, chest pain, no fever.
2. Flu-like with fever: Headache, loss of smell, cough, sore throat, hoarseness, fever, loss of appetite.
3. Gastrointestinal: Headache, loss of smell, loss of appetite, diarrhea, sore throat, chest pain, no cough.
4. Severe level one, fatigue: Headache, loss of smell, cough, fever, hoarseness, chest pain, fatigue.
5. Severe level two, confusion: Headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, confusion, muscle pain.
6. Severe level three, abdominal and respiratory: Headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, confusion, muscle pain, shortness of breath, diarrhea, abdominal pain.