Recurrent_case
Total viral RNA was extracted from oropharyngeal samples using the QIAamp Viral RNA Mini Kit (Qiagen, Germany). Amplification of SARS-CoV-2 viral RNA was conducted using ULSEN Ultra-sensitive Novel Coronavirus Whole-genome capture Kit (Beijing MicroFuture, Beijing, China). Library was constructed using NexteraXT DNA Library Preparation Kit (Illumina, CA, USA), and sequenced on the MiniSeq sequencing platform (Illumina, CA, USA) following the manufacturer's instructions.