Translation: Diagnosis and Treatment Protocol for COVID-19 (Trial Version 9)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belongs to the β-genus coronaviruses. It has an envelope, and the virus particle is round or oval, with a diameter ranging from 60 to 140 nm. The genome of SARS-CoV-2 contains five essential genes, which encode four structural proteins, namely, the nucleoprotein (N) protein, the envelope (E) protein the matrix protein (M), and the spike (S) protein and an RNA-dependent RNA polymerase (RdRp). The RNA genome is wrapped in the N protein, forming a nucleocapsid surrounded by lipid bilayer membrane, in which the E protein, theMprotein and the S protein are embedded. The S protein interacts with angiotensin-converting enzyme 2 (ACE2) to enter cells. When isolated and cultured in vitro, SARS-CoV-2 can be found in human respiratory epithelial cells in approximately 96 hours; nevertheless, it takes approximately 4–6 days for the virus to be found if isolated and cultured in Vero E6 and Huh-7 cell lines. Similar as observed for other viruses, mutations can occur in the genome of SARS-CoV-2, some ofwhichmay result in changes in the biological characteristics of the virus, thus attracting extensive attention. For instance, changes in the affinity of the S protein for ACE2 can affect the ability of the virus to invade host cells, the ability to replicate and spread, the production of antibodies in convalescent patients and vaccinated people, and the neutralization ability of antibody drugs. Five variants of concern, namely, alpha, beta, gamma, delta, and omicron, have been proposed by the World HealthOrganization. At present, the omicron variant has replaced the delta variant as the main epidemic variant. Evidence has shown that compared with the delta variant, the omicron variant displays stronger transmissibility and weaker pathogenicity. For the omicron variant, the diagnostic accuracy of polymerase chain reaction (PCR)