Researchers Identify 6 Types of COVID-19 Based on Symptoms

A team of researchers has identified six different “types” of COVID-19, each determined by a cluster of symptoms. Each type is associated with how severe of an illness a patient might experience, as well as who might need respiratory support.

The pre-print study, which was published in MedRxiv last month, analyzed data from the COVID Symptom Study app, an app that asks people to log their daily symptoms, whether they feel sick or not. Researchers analyzed data from 1,600 app users in the U.K. and U.S. with confirmed cases of COVID-19 who had regularly logged their symptoms in March and April.

While people who contract COVID-19 can experience a range of symptoms, including fever, cough, headaches, muscle pains, fatigue, diarrhea, confusion, loss of taste and smell, and shortness of breath, the analysis found that there were six different groupings of symptoms people typically experienced. 

Once they determined these groupings, researchers analyzed a second independent dataset of 1,000 users in the U.K., U.S., and Sweden who had logged their symptoms in May. The "types" still applied.

What Are the 6 Different "Types" of COVID-19?

The researchers broke the symptom combinations into these clusters:

1.   Flu-like with no fever: Headache, loss of smell, muscle pain, 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

It’s important to note that researchers looked at one strain of COVID-19—not any potential mutations beings explored outside of this study. Despite this being the same virus, study co-author Claire Steves, PhD, a clinical senior lecturer at King's College London, tells Verywell that COVID-19 "appears to present differently in different people.”

SARS-CoV-2, the virus that causes COVID-19, “can get into a whole range of different cell types, not only respiratory cells,” Steves says. As a result, it can cause brain symptoms like confusion, skin symptoms like a rash, and respiratory symptoms like a cough, she explains. “The immune response each of us has to [COVID-19] is different, which also contributes to different presentations,” she says.

Which Types of COVID-19 Are Most Serious?

Once they identified the different clusters of symptoms, the researchers conducted an analysis to see what falling into one of these clusters meant for a patient’s treatment.

The researchers discovered that only 1.5% of people in cluster 1, 4.4% of people in cluster 2, and 3.7% of people in cluster 3 required some kind of breathing support. But those numbers jumped up for people in the other clusters. 8.6% of those in cluster 4, 9.9% of those in cluster 5, and 19.8% in cluster 6 needed either supplemental oxygen or to be put on a ventilator.

Nearly half of the patients in cluster 6 ended up in the hospital, but only 16% of people in cluster 1 had the same experience.

In general, the researchers found that people in clusters 4, 5, and 6 were more likely to be high risk for COVID-19—they were older and frailer, and more likely to have pre-existing conditions like diabetes, lung disease, or obesity.

How Can This Help People With COVID-19?

To learn about the real-life implications of their data, researchers created a model that combined information about the patient’s age, sex, body mass index (BMI), and pre-existing conditions with the symptoms they experienced over the first five days of their illness. Based on those factors, the researchers were able to predict which “type” of COVID-19 a patient had and their risk of developing a serious case of illness.

People who develop a severe case of COVID-19 and need breathing support typically go the hospital around 13 days after their first symptoms develop—and Steves says the new data can help get people treatment sooner.

“We can use the way [the virus] presents in the first five days to predict who needs support from the hospital,” she says. “This means we could get in earlier with the higher risk people, monitoring and supporting them at home, and possibly giving treatments we now know might be effective.”

Early intervention may be important in some cases, Peter Winkelstein, MD, a professor and executive director at the Institute for Healthcare Informatics at the University at Buffalo, who did not work on the study, tells Verywell.  

"We don't know yet for sure with COVID-19—we're still learning more about the virus—but it's certainly true in almost all of medicine that the earlier you start treatment, the better a patient ends up doing," he says.

Steves says she hopes her team’s findings will lead to “proactive monitoring” of patients who test positive for COVID-19—and hopefully create better outcomes in the future.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.