A new study of COVID-19, based on data from a symptom tracker app, determined that there are six distinct "types" of the disease involving different clusters of symptoms. The discovery could potentially open new possibilities for how doctors can better treat individual patients and predict what level of hospital care they would need.
Researchers from King's College London studied data from approximately 1,600 U.K. and U.S. patients who regularly logged their symptoms in the COVID Symptom Tracker App in March and April.
Typically, doctors will look for key symptoms such as cough, fever and loss of the sense of smell to detect COVID-19. The study, which has not been peer-reviewed, says the six different "types" of COVID-19 can vary by severity and come with their own set of symptoms.
"I think it's very, very interesting," Dr. Bob Lahita, who is not affiliated with the study, told CBSN anchors Vladimir Duthiers and Anne-Marie Green. "Among the patients I see, those who recovered, many of them present different ways: some people with fever and some without fever, and some with nausea and vomiting, some people with diarrhea, etc."
The six clusters of symptoms outlined in the study are:
The first level, "flu-like with no fever," is associated with headaches, loss of smell, muscle pains, cough, sore throat and chest pain. Patients at this level have a 1.5% chance of needing breathing support such as oxygen or a ventilator.
The second type, "flu-like with fever," includes symptoms like loss of appetite, headache, loss of smell, cough, sore throat, hoarseness and fever. Researchers say about 4.4% of patients at this level needed breathing support.
Patients with the third type, simply described as "gastrointestinal," do not have a cough as part of their illness. Instead, they experience headache, diarrhea, loss of smell, loss of appetite, sore throat and chest pain, and about 3.3% needed breathing support.
Lahita referred to the following three clusters of COVID-19 as the "really severe types."
In type four, or "severe level one," patients experience fatigue along with headache, loss of smell, cough, fever, hoarseness and chest pain. Patients at this level needed breathing support at a rate of 8.6%.
Type five, "severe level two," includes the symptoms of type four along with loss of appetite, sore throat and muscle pain, and is mainly distinguished by confusion.
"That means you don't know where you are or where you live, whether you are in or out of the hospital, who your relatives are," Lahita explained. "That is very scary."
Almost 10% of patients at that level need breathing support.
The most severe type of COVID-19 is referred to as "severe level three, abdominal and respiratory," and has all the above symptoms along with abdominal pain, shortness of breath and diarrhea. Nearly 20% of these patients need breathing support.
"Those are the severe level threes who wind up on a ventilator, and then it is touch-and-go as to whether they survive the infection entirely," Lahita said.
The U.K. researchers also found that only 16% of patients with type one COVID-19 required hospitalization, compared with nearly half of the patients with type six.
Patients in the severe clusters also tended to be older or with pre-exisiting conditions and weakened immune systems, compared to those in the first three.
Scientists hope the discovery, once further studied, could help predict what types of care patients with COVID-19 might need, and give doctors the ability to predict which patients would fall into which category.
"I'm very happy that these six types have been identified and can give us an idea of a prognosis going forward for patients who are afflicted with this virus," Lahita said.