A new study found that COVID-19 symptoms come in six different clusters, which may help predict which patients are more at risk and in need of respiratory support.

For the study, researchers used a machine learning algorithm to analyze data from more than 1,600 patients in the U.S. and the U.K. who had tested positive for COVID-19 and had regularly logged their symptoms on the Zoe health app in March and April. Researchers then tested the algorithm by using it on an additional 1,047 patients in the U.S., the U.K. and Sweden, who entered their symptoms on the app throughout May.

The study identified six clusters of symptoms:

Cluster 1 (flulike with no fever): Headache, loss of smell, muscle pains, cough, sore throat, chest pain, no fever

Cluster 2 (flulike with fever): Headache, loss of smell, cough, sore throat, hoarseness, fever, loss of appetite

Cluster 3 (gastrointestinal): Headache, loss of smell, loss of appetite, diarrhea, sore throat, chest pain, no cough

Cluster 4 (severe level one, fatigue): Headache, loss of smell, cough, fever, hoarseness, chest pain, fatigue

Cluster 5 (severe level two, confusion): Headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, confusion, muscle pain

Cluster 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