PCR: Polymerase chain reaction is a laboratory test that uses a segment of DNA as a template that is expanded to a sufficient amount for structural and functional analysis in the presence of DNA polymerase and nucleotide substrates. Specimen collection, including pharyngeal swabs, nasal swabs, sputum, bronchial lavage, alveolar lavage, urine, and pleural fluid, is first performed and sent to specialized institutions for nucleic acid extraction. Viral RNA first needs to be transcribed into CDNA, and then the expansion test is performed with a designated fluorescent quantitative PCR instrument. specimen collection, preservation, transfer, nucleic acid extraction, transcription, and testing have strict requirements. PCR testing is mainly used clinically for infectious disease, tumor, and genetic disease detection, clear diagnosis, and targeted treatment.