Dynamics and Correlation Among Viral Positivity, Seroconversion, and Disease Severity in COVID-19

Abstract

BACKGROUND: The understanding of viral positivity and seroconversion during the course of coronavirus disease 2019 (COVID-19) is limited. OBJECTIVE: To describe patterns of viral polymerase chain reaction (PCR) positivity and evaluate their correlations with seroconversion and disease severity. DESIGN: Retrospective cohort study. SETTING: 3 designated specialty care centers for COVID-19 in Wuhan, China. PARTICIPANTS: 3192 adult patients with COVID-19. MEASUREMENTS: Demographic, clinical, and laboratory data. RESULTS: 0.001). In patients with laboratory-confirmed COVID-19, the IgM-positive rate was 19.3% in the first week, peaked in the fifth week (81.5%), and then decreased steadily to around 55% within 9 to 10 weeks. The IgG-positive rate was 44.6% in the first week, reached 93.3% in the fourth week, and then remained high. Similar antibody responses were seen in clinically diagnosed cases. Serum inflammatory markers remained higher in critically ill patients. Among noncritically ill patients, a higher proportion of those with persistent viral positivity had low IgM titers (<100 AU/mL) during the entire course compared with those with short viral positivity. LIMITATION: Retrospective study and irregular viral and serology testing. CONCLUSION: The rate of viral PCR positivity peaked within the initial few days. Seroconversion rates peaked within 4 to 5 weeks. Dynamic laboratory index changes corresponded well to clinical signs, the recovery process, and disease severity. Low IgM titers (<100 AU/mL) are an independent risk factor for persistent viral positivity. PRIMARY FUNDING SOURCE: None.