COVID-19 Reinfection or Relapse? A Retrospective Multicenter Cohort Study from Iran

Returning symptomatic patients with a history of recovered COVID-19 with a new positive SARS CoV-2 PCR test after several weeks to months of a negative PCR result is challenging during the COVID-19 pandemic.

We aimed to determine such Iranian patients’ clinical and laboratory characteristics and discuss possible reasons.

We retrospectively investigated SARS CoV-2 PCR tests in three referral hospitals. All patients who had the following criteria were included in the study: two SARS CoV-2 PCR-positive tests three months apart, no symptoms, a negative PCR test between the two positive tests, and access to the patient and medical information. Then, we retrospectively recorded the clinical and laboratory characteristics of the eligible patients. We also compared the clinical and laboratory features in the first and second episodes.

Among 1,899 patients, 37 cases were eligible in the study based on our criteria. The majority of patients were males and nurses. The mean age was 37.54 ± 15.16 years. Weakness, myalgia, and fever were the most frequent clinical symptoms in both episodes. The mean interval between discharge and second presentation was 117 ± 61.42 days. The clinical, radiological, and laboratory characteristics were not significantly different between the two episodes, except for significantly more dexamethasone use in the second episode (P = 0.03).

We could not cultivate the virus and perform the phylogenic sequencing of SARS-CoV-2; however, the prolonged interval between the two episodes suggests probable reinfection in our cases. Finally, this clinical phenomenon may be more common in HCW without a significant consequence; however, most cases were HCW who had more compatibility with our criteria due to the availability of their medical information