**2. Materials and Methods**

#### *2.1. Study Design and Subjects*

This study is a retrospective cohort study in which consultation data were collected from the COVID-19 follow-up health consultation program and analyzed retrospectively. The program for recovered patients started on 9 March and ended on 5 June 2020. During this

period, all patients who had been released from quarantine in Gyeongsangbukdo province were asked to participate in the consultation program in Daegu [15]. As of the date of approval of the research protocol, 1679 (26.9%) of 6247 recovered patients agreed to participate.

A diagnosis of COVID-19 was based upon the isolation of the SARS-CoV-2 virus from a nasopharyngeal sample or detection of a specific gene in a PCR test. A recovered patient was defined as an individual who had met the following clinical and test criteria: absence of fever, improvement in clinical symptoms without the need for antipyretic drugs, and negative results from two PCR tests conducted with an interval of at least 24 h [1]. Subjects who (i) withdrew consent for consultation, (ii) did not respond or could not be contacted by phone, and (iii) were under 18 years-of-age and did not have consent from the primary guardian were excluded. The study complied with the tenets of the Helsinki Declaration and was approved by the Institutional Review Board of the local hospital (protocol No. YUMC 2020-04-112).

Selected subjects were classified into two groups in accordance with the total number of consultations received during the study period: those who required or requested one consultation and those who required or requested more than one consultation.
