Viral and Antibody Kinetics of COVID-19 Patients with Different Disease Severities in Acute and Convalescent Phases: A 6-Month Follow-Up Study

Abstract

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread rapidly around the world, posing a major threat to human health and the economy. Currently, long-term data on viral shedding and the serum antibody responses in COVID-19 patients are still limited. Herein, we report the clinical features, viral RNA loads, and serum antibody levels in a cohort of 112 COVID-19 patients admitted to the Honghu People’s Hospital, Hubei Province, China. Overall, 5.36% (6/112) of patients showed persistent viral RNA shedding (> 45 days). The peak viral load was higher in the severe disease group than in the mild group (median cycle threshold value, 36.4 versus 31.5; P = 0.002). For most patients the disappearance of IgM antibodies occurred approximately 4–6 weeks after symptoms onset, while IgG persisted for over 194 days after the onset of symptoms, although patients showed a 46% reduction in antibodies titres against SARS-CoV-2 nucleocapsid protein compared with the acute phase. We also studied 18 asymptomatic individuals with RT-qPCR confirmed SARS-CoV-2 infection together with 17 symptomatic patients, and the asymptomatic individuals were the close contacts of these symptomatic cases. Delayed IgG seroconversion and lower IgM seropositive rates were observed in asymptomatic individuals. These data indicate that higher viral loads and stronger antibody responses are related to more severe disease status in patients with SARS-CoV-2 infection, and the antibodies persisted in the recovered patient for more than 6 months so that the vaccine may provide protection against SARS-CoV-2 infection. Electronic supplementary material The online version of this article (10.1007/s12250-020-00329-9) contains supplementary material, which is available to authorized users.

The Characterization of Disease Severity Associated IgG Subclasses Response in COVID-19 Patients

“…Our studies demonstrated that NAb, IgA, and total levels of IgG and IgM were not correlated with viral load in COVID-19 patients, while a weakly inverse correlation between IgG subclasses and viral load was observed. Our findings are consistent with two prior studies, which also reported no correlation between persistent SARS-CoV-2 RNA and NAb titers ( 24 , 40 ). Slim Fourati et al reported a lower early antibody responses were related to higher viral load in nasopharyngeal swabs in the severely ill COVID-19 patients ( 41 ), though the study may be limited by its smaller sample size.…”

Human cell receptors: potential drug targets to combat COVID-19

“…The in silico studies indicated that HIV-1 protease inhibitors Lopinavir and Ritonavir (Nutho et al 2020 ) is a novel M pro inhibitors. However, in vitro and in vivo studies showed that these inhibitors could not reach the effective pharmacokinetic concentration for inhibiting M pro (Zhang et al 2020b ).…”

Passive Immunity Should and Will Work for COVID-19 for Some Patients

“…Whether for enzyme immunoassay-detected antibody (or similar) or neutralizing antibody, the total specific antibody level peaks after 3-10 weeks [30,[51][52][53][54][55][56][57][58][59][60]. As anticipated, IgM reactivity diminishes over the first few months while IgG reactivity continues to be detected for a much longer interval [54,56,57,59,[61][62][63][64][65][66][67]. The finding of rapid IgG response relative to IgM suggests a possible priming from past exposure to endemic respiratory coronaviruses [34].…”

“…Different antibody responses decay variably and dependent on the nature of the antibody target and severity of disease [33,50,54,59,61,68,75,76,78,83,87,95,96,[100][101][102][103]. The latter includes measurable neutralizing antibody, and the decay in some patients after 1 month can be such that donations with desirable high titres elapse quickly in convalescence after infection [49,54,[103][104][105][106].…”