(Newser)
– One year after the World Health Organization declared COVID-19 a pandemic, researchers are still working to understand the disease – and why some patients still show symptoms months after being infected. According to a new study, many “long-haulers” coronaviruses experienced only mild symptoms, or none, during their initial infection. The study looked at the medical records of 1,407 people in California who tested positive but were never hospitalized. The researchers say that there are probably many more undiagnosed cases of long COVID. “We know that some of the long-distance symptoms appear long after two months,” says co-author Dr. Natalie Lambert to the New York Times. “So there is a potential for a wide range of long-distance symptoms that they are not going to associate with COVID.”
The study found that just over a quarter of patients, 59% of them women, reported symptoms more than 60 days after infection. Lambert also interviewed more than 5,000 people contacted via the Survivor Corps website for long distances, reports NBC News. She says that while more research is needed, the first findings suggest that the symptoms initially appear in waves, with fever, chills and gastrointestinal symptoms arriving in the early stages, as with long-distance patients, followed by heart problems and blood pressure around 15 days in, and symptoms like mouth sores and “COVID toes” arriving a week after that. After 60 days, the researchers say, symptoms such as coughing, muscle aches, headaches and increased heart rate arrive in groups that can change from day to day. The study did not look at “brain fog”, which doctors say is also a common long-distance symptom. (Read more coronavirus stories.)