App that tracks COVID-19 symptoms shows startling variety, including numb fingers and toes

A smartphone app that tracks COVID-19 symptoms has collected information from more than 4 million people worldwide, and is giving doctors a closer look at the different symptoms patients are experiencing.

The variety of different symptoms people are exhibiting with COVID-19 is startling.

"I've seen more varied presentations of COVID that anything I can think of in my career so far," said Dr. Troy Pennington of Arrowhead Regional Medical Center in Colton.

The app, called the COVID Symptom Study, was created by doctors and scientists at Massachusetts General Hospital, The Harvard T.H. Chan School of Public Health, King's College London and Stanford University School of Medicine, working along with ZOE, a health science company. Users can input their own health information and get statistics on those also participating around their area.

Researchers grouped patients into six different clusters. The first cluster of patients are those experiencing the mildest symptoms.

"These were individuals who came in with flu-like symptoms," said Pennington, who was not part of the research team responsible for the study. "Body aches, perhaps a sore throat, mild shortness of breath, and mostly mild symptoms. But no fever."

The second cluster of patients exhibited similar symptoms, but with fever. The third group of patients added gastrointestinal problems.

"It also had a GI component with some mild diarrhea, or even upset stomach," he added.

The fourth cluster added severe fatigue; the fifth added confusion. The sixth cluster was made up patients with the most serious symptoms, including abdominal and respiratory problems.

"That group had all of the common features of flu-like illness, but it had a very significant GI component, with persistent abdominal pain and diarrhea. Those were hallmarks of that cluster along with severe shortness of breath, chest pain, fever, and headache," he said.

Pennington said some of his patients at Arrowhead Regional Medical Center have shown even more peculiar symptoms.

"We've seen presentations with unusual rashes, rashes that look like hives, chicken pox."

One patient was complaining of numb fingers and toes.

"She had a little bit of fatigue and a mild headache, but she was complaining of cold hands and feet, and an unusual rash. So it's been humbling to physicians, because the presentation of COVID-19 has been so varied."

According to the study, the only symptoms that were common in all six clusters were headaches and loss of smell.