Repeat COVID infections tied to higher odds of new health conditions by Laine Bergeson, Sept 10, 2026, CIDRAP
Adults who reported having COVID-19 at least twice were significantly more likely to be diagnosed as having a new medical condition than those who reported never having been infected, according to a study published this week in Canada Communicable Disease Report.
It’s well known that preexisting conditions can increase the risk of severe COVID. The new research suggests that the relationship between COVID and chronic illness may run in both directions.
For the study, researchers from the Public Health Agency of Canada and Statistics Canada analyzed data collected from April 2022 to June 2023 from nearly 9,000 respondents to the Canadian COVID-19 Antibody and Health Survey and Follow-up Questionnaire.
Participants reported how many confirmed or suspected COVID infections they had and whether they had been diagnosed as having any of 21 conditions after their first COVID infection. Conditions included respiratory, cardiovascular, neurologic, and musculoskeletal disorders, as well as diabetes, cancer, sleep apnea, bowel and bladder disorders, mental illnesses, and chronic fatigue syndrome or fibromyalgia.
5-fold higher odds of respiratory diagnosis
Roughly 47% of participants reported having one COVID infection, and approximately 20% reported two or more infections. Of all participants, 11% reported developing a new medical condition during the study period.
The researchers found that those reporting two or more infections had 76% higher odds of receiving a new diagnosis than those reporting no infections (adjusted odds ratio [aOR], 1.76).
Continued investigation into the long-term sequelae of SARS-CoV-2 infections, particularly reinfections, and the biological, behavioural and systemic factors that may mediate the effects of these infections is needed.
Repeat infections were also associated with five times the odds of a respiratory diagnosis (aOR, 5.03) and nearly four times the odds of developing back problems (aOR, 3.79), although the confidence intervals were wide, indicating greater uncertainty.
Respondents who experienced acute symptoms that interfered with daily activities during a first infection were also 63% more likely to receive a new diagnosis (aOR, 1.63). Those who experienced symptoms three or more months after an infection had more than three times the odds of receiving a new diagnosis (aOR, 3.35).
More healthcare visits may mean more diagnoses
The results cannot establish that the infections caused the new diagnoses, the researchers caution. They also note that all the health information was self-reported, which allows for the possibility of misremembered symptom severity. And, they warn, some participants who reported no infections may have had asymptomatic or undiagnosed COVID.
Healthcare-seeking behavior may also have influenced the findings. Those with severe or persistent symptoms may have visited healthcare providers more often, creating the opportunity for other health conditions to be diagnosed.
Still, write the researchers, the findings “reinforce the continued importance of public health efforts to prevent infection.
“Continued investigation into the long-term sequelae of SARS-CoV-2 infections, particularly reinfections, and the biological, behavioural and systemic factors that may mediate the effects of these infections is needed,” they wrote.
“Such investigations could assist healthcare practitioners in tailoring COVID-19 vaccine recommendations and post COVID-19 monitoring for new health conditions and guide public health practice and messaging when promoting COVID-19 vaccine uptake and personal protective measures (e.g., masking) to prevent and minimize the severity of infections, as well as the potential development of new health conditions,” they added.