COVID-19 may not be just one disease, but six distinct types, a new British study claims.
Each type differs in severity and in the need for respiratory support during hospitalization, the researchers added.
Cough, fever and loss of smell are the usual symptoms of COVID-19, but the range of symptoms can include headaches, muscle pain, fatigue, diarrhea, confusion, loss of appetite, shortness of breath and more.
For the study, the researchers analyzed data on 1,600 people who reported their symptoms into an app.
The six symptom groups in a sequence from least to most severe are:
The last three types are tied with the most severe disease, the researchers noted. The range of those with severe symptoms who need help breathing range from about 9% to 20%, while those with milder symptoms who need breathing aids range from 2% to 3%.
Also, nearly half of the patients with the most severe symptoms ended up in a hospital, compared with 16% of those with the least severe symptoms, the findings showed.
Using a mix of symptoms, body weight and other factors, the researchers developed a model that predicts which patients will need to be hospitalized and need breathing support.
"These findings have important implications for care and monitoring of people who are most vulnerable to severe COVID-19," said researcher Dr. Claire Steves, from King's College London.
"If you can predict who these people are at day five, you have time to give them support and early interventions such as monitoring blood oxygen and sugar levels, and ensuring they are properly hydrated -- simple care that could be given at home, preventing hospitalizations and saving lives," Steves said in a college news release.
The report was published online July 28 on medRxiv, a preprint server that does not include the rigors of peer review.
For more on COVID-19, head to the U.S. Centers for Disease Control and Prevention.