Researchers ID 6 COVID-19 Symptom Sets

  • COVID-19 presents differently in people. Some experience mild or no symptoms, while others may require hospitalization and oxygen support.
  • Researchers in London were able to identify which COVID-19 symptom clusters tend to be more severe and require respiratory support.
  • Cough, fever, and changes in smell were the most frequently reported symptoms, followed by headaches, muscle aches, fatigue, confusion, shortness of breath, and loss of appetite.

New research has discovered there are primarily six different symptom “sets” of COVID-19.

COVID-19 presents differently in people. Some experience mild or no symptoms, while others may require hospitalization and oxygen support.

Because of COVID-19’s unpredictability, it can be difficult for doctors to accurately predict which patients will need more intensive care.

Understanding not just the variety of symptoms but how different collections of symptoms are associated with worse outcomes can help doctors treat patients.

Researchers from King’s College London published their findings this week and were able to identify which types tend to be more severe and require respiratory support, according to the study, which hasn’t yet been peer-reviewed.

Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital in New York City, says these findings offer an innovative solution to identifying who may be more at risk for developing a more serious form of COVID-19.

“It’s these patients we must be able to spot quickly, before they deteriorate and require ICU-level of care and monitoring,” Glatter told Healthline.

The clusters explained

The researchers developed a phone application — called the COVID Symptom Study app — in which people with a COVID-19 diagnosis logged their symptoms on a daily basis.

The app’s machine-learning algorithm was able to map out which symptoms typically present together and whether that would indicate how severe the illness will be.

Cough, fever, and changes in smell were the most frequently reported symptoms, followed by headaches, muscle aches, fatigue, confusion, shortness of breath, and loss of appetite.

After evaluating symptom trends, the research team identified six distinct symptom clusters:

  1. Flu-like with no fever: headache, loss of smell, muscle pain, cough, sore throat, chest pain, and no fever
  2. Flu-like with fever: fever, loss of appetite, headache, loss of smell, sore throat, hoarseness
  3. Gastrointestinal: diarrhea, headache, loss of smell, loss of appetite, sore throat, chest pain, no cough
  4. Severe level 1, fatigue: fatigue, headache, loss of smell, cough, fever, hoarseness, chest pain
  5. Severe level 2, confusion: confusion, headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, muscle pain
  6. Severe level 3, abdominal and respiratory: shortness of breath, diarrhea, abdominal pain, headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, confusion, muscle pain
Here’s how severe the clusters are

The research team also wanted to see how severe each cluster tends to be.

They found just 1.5 percent of those with the first cluster (Flu-like with no fever), 4.4 percent of people with the second (Flu-like with fever), and 3.3 percent in the third (Gastrointestinal) needed respiratory support when hospitalized.

The severity increased with the latter half of clusters, which tended to include people who were frailer, older, and had underlying health conditions, such as diabetes or lung disease.

“It seems like, from the preliminary results of the study, that older, frailer, and medically complex patients (with preexisting conditions) have lots of symptoms, and thus more severe disease,” said Dr. Kirsten Bechtel, a Yale Medicine pediatric emergency medicine physician who has worked in the ICU during the pandemic, noting that this aligns with previous evidence.

With cluster 4 (Severe level 1), 8.6 percent of people needed breathing support. Nearly 10 percent in cluster 5 (Severe level 2) and 19.8 percent in cluster 6 (Severe level 3) needed breathing support.

The researchers then factored in age, sex, body mass index (BMI), and preexisting health conditions to successfully predict who would experience which specific cluster just 5 days after they experienced their first symptom.

COVID-19 presents differently in people

One of the factors about COVID-19 that’s had infectious disease specialists stumped is how differently the infection presentsTrusted Source in people.

Where some people with an infection won’t have any symptoms, others will experience widespread inflammation along with life threatening lung and kidney damage.

Additionally, most people will be able to recover on their own at home, but a small percentage who develop a severe infection will need to get supportive care at the hospital.

Seeing as the disease presents so differently from person to person, it can be tricky for doctors to predict how the disease will play out in any given patient.

These findings could help doctors better predict which patients have a higher risk for death, says Bechtel.

The data may also be instrumental in helping doctors allocate available resources, according to Glatter.

Why catching the disease early matters

It’s become increasingly clear that when people go to the hospital matters.

“Earlier diagnosis and intervention in patients with COVID-19 may potentially help to reduce the risk for requiring mechanical ventilation, decrease length of hospital stay, and risk for developing thrombotic complications,” Glatter said.

Many people with severe COVID-19 don’t go to the hospital until they’ve been sick with COVID-19 for at least a week.

Multiple studies have found that late intervention is directly linked with a higher death rate.

“If patients wait, the inflammatory phase of the disease can lead to severe lung disease, which could lead to respiratory failure and the need for intensive respiratory support, like a ventilator,” Bechtel said.

Some people with COVID-19 experience hypoxia, a condition where the body doesn’t get enough oxygen. These people need oxygen support immediately; a delay could jeopardize the trajectory of the disease.

Furthermore, those with inflammation in the lungs need to rest, so avoiding daily responsibilities — like taking care of others, preparing food, and doing chores — is crucial.

Intervening early, with the help of these findings, can help improve the outcomes of people who get COVID-19.