The incidence of Covid-19 complications was similar to that of influenza complications, a local study showed.
However, compared to flu patients, Covid-19 patients had a higher incidence of heart failure, mood disorders, dementia, and hair loss. This indicates that high-risk groups with the cited diseases need to pay more attention to complication management.
A joint research team of the Health Insurance Review and Assessment Service, the National Medical Center, and Seoul National University Bundang Hospital released the study results that compared the complications of Covid-19 and influenza. The study was based on HIRA’s insurance claim data.
The research team utilized and analyzed the HIRA’s big data on 21,615 Covid-19 patients and 2,380,696 patients diagnosed with flu and received antiviral medications last year.
A complication was defined as a newly developed disease in a person who had not visited a medical institution due to a particular condition for three years before being diagnosed with Covid-19 or flu but visited an institution due to the new disease.
Then, the research team checked the incidence of a digestive system problem, a musculoskeletal system problem, periodontal disease, dermatitis, hair loss, asthma, chronic obstructive pulmonary disease, pneumonia, cardiovascular disease, heart failure, cerebrovascular disease, autoimmune disease, mood disorder, and dementia.
The results showed that the incidence of complications was 19.1 percent in Covid-19 patients and 28.5 percent in flu patients.
In most diseases, the relative risk (of complications was lower in Covid-19 patients than in flu patients. However, in dementia (RR 1.96), heart failure (RR 1.88), mood disorder (RR 1.73), and hair loss (RR 1.52), the incidence was higher in Covid-19 patients than in flu patients.
The incidence of complications in Covid-19 patients was higher in those aged between 20 and 44, beneficiaries of health insurance coverage, Daegu and North Gyeongsang Province residents, and hospitalized patients with mild symptoms.
The incidence of serious complications such as pneumonia, cardiovascular disease, heart failure, and cerebrovascular disease was higher in the elderly and those with comorbidities.
“The incidence of complications in Covid-19 patients was similar to or lower than that of flu patients, but the incidence of heart failure, mood disorder, dementia, and hair loss was higher in Covid-19 patients. So, people at higher risk with those diseases should manage complications carefully,” the research team said.
The research team noted that the study did not include patients who did not visit a medical institution and that actual symptoms of discomforts caused by Covid-19 and flu could be different from estimated results.
Lee Jin-yong, the corresponding author and director of the HIRA Research Institute, said, “As the incidence of complications from Covid-19 is not high, and if vaccination can lower the fatality, the nation could change Covid-19 management strategy to focus on patients with symptoms only, just like flu.”
Professor Lee Hye-jin of the SNU Bundang Hospital, the paper's first author, said despite concerns about the pandemic, the relatively low incidence of complications from Covid-19 compared to that of flu was a positive aspect.
“Still, the ongoing Covid-19 pandemic could paint a different picture depending on variants, and the long-term complications are unknown. Thus, it is still important to prevent Covid-19 infections,” she said.
The study was released in Emerging Infectious Diseases, a journal published by the U.S. Centers for Disease Control and Prevention.