Nearly half of people who contract mild or moderate cases of COVID-19 still experience symptoms six months later, according to a new study published by Israeli researchers.
The research, which is slated to be published this month in the Journal of Clinical Microbiology and Infection, evaluated 103 people over the age of 18 who had coronavirus between April and October 2020. The people had mild to moderate symptoms, meaning that while they were not asymptomatic, they were not hospitalized with a more severe case of the disease.
Participants were interviewed up to four times over the course of the study.
“It is very scary that after six months, young people who were healthy and feeling fine before coronavirus still have symptoms,” said Dr. Sarah Israel of Hadassah-University Medical Center, who helped author the report.
At six months, 46% of the patients had at least one unresolved symptom, most commonly fatigue (22%), smell and taste changes (15%) or breathing difficulties (8%).
The study showed that 44% of people experienced headache, 41% fever, 39% muscle aches and 38% dry cough as their first COVID-19 symptom, usually around the second day of disease onset. But many of those symptoms resolved themselves relatively quickly.
In contrast, smell and taste changes, which usually appeared around the fourth day after disease onset, were among the longest lasting.
A total of 14 symptoms were included in the final analysis, 12 of which were listed as symptoms of COVID-19 by the Centers for Disease Control and Prevention (CDC) as of December 2020. These include taste change, smell change, fever, dry cough, productive cough, muscle aches, headache, runny nose, sore throat, diarrhea, breathing difficulty, vomiting and nausea.
In addition, more than half of participants (53%) complained of a non-CDC symptom: loss of appetite.
Finally, fatigue, which is now listed as a CDC symptom, did not explicitly appear in the original questionnaire but was self-reported by 18% of the patients under “any other symptoms.”
Other symptoms that were mentioned by some of the patients included memory loss, hair loss and depression, “many symptoms for which it is hard to understand why patients were experiencing these post-COVID,” Israel said
“Long COVID is emerging as a phenomenon where patients have long-term unresolved symptoms,” the report said. “These could be prolonged symptoms of COVID-19, or a post-COVID syndrome for which dysfunction of the autonomic nervous system has been proposed, although further research is needed to establish the causes.”
Most of the patients were generally healthy before contracting the virus. Two of them had high blood pressure, six had respiratory disease, two had cardiac disease, and 16 were clinically obese.
The study did have several limitations, the report said, including that the data-collection method used, calling patients at various intervals, could have caused recall bias. In addition, patients were recruited via social networks and word of mouth; therefore, they constituted a largely younger cohort with higher incomes and levels of education.
Israel said she hoped the information in the report would enable doctors to better understand COVID-19’s long-term health complications and that it will serve to encourage young people to get vaccinated.
“I think people now know that this is not an easy virus,” she said. “Even if you hardly get sick, the virus can affect you for months afterward. The risk of the side effects from the vaccine is small in comparison to the symptoms of the virus.”
Additional work should be done to evaluate whether asymptomatic patients experience similar symptoms after recovery, Israel said. The team hopes to continue surveying the people involved in the current study to determine when their existing symptoms go away, she added.