Abstract
While many patients infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) eventually produce neutralising antibodies, the degree of susceptibility of previously infected individuals to reinfection by SARS-CoV-2 is currently unknown. To better understand the impact of the immunoglobulin (IgG) level on reinfection in recovered coronavirus disease 2019 (COVID-19) patients, anti-nucleocapsid IgG levels against SARS-CoV-2 were measured in 829 patients with a previously confirmed infection just after their recovery. Notably, 87 of these patients had no detectable IgG concentration. While there was just one case of asymptomatic reinfection 4.5 months after the initial recovery amongst patients with detectable anti-nucleocapsid IgG levels, 25 of the 87 patients negative for anti-nucleocapsid IgG were reinfected within one to three months after their first infection. Therefore, patients who recover from COVID-19 with no detectable anti-nucleocapsid IgG concentration appear to remain more susceptible to reinfection by SARS-CoV-2, with no apparent immunity. Also, although our results suggest the chance is lower, the possibility for recovered patients with positive anti-nucleocapsid IgG findings to be reinfected similarly exists.
Highlights
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a 2019 novel coronavirus 2019-nCoV [1], severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was named so given the similarity of its symptoms to those induced by severe acute respiratory syndrome [2]
This study aimed to report an additional group of COVID-19 patients who were reinfected by SARS-CoV-2 and argue that the IgG level is a potential marker of the reinfection risk
Our study found that 86 patients tested negative for IgG specific to SARS-CoV-2 after recovery among a population of 829 patients who were infected with SARS-CoV-2 for the first time
Summary
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a 2019 novel coronavirus 2019-nCoV [1], severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was named so given the similarity of its symptoms to those induced by severe acute respiratory syndrome [2]. The clinical manifestations of COVID-19 range widely from asymptomatic to mild, moderate and rapidly progressive severe (pneumonia) disease that can lead to death in some individuals [3,4,5]. The moderate clinical symptoms of patients with COVID-19 include fever, dyspnoea, fatigue, dry cough, myalgia and pneumonia. In severe cases, affected patients may experience acute respiratory failure, septic shock and organ failure that might culminate in death [6,7]. Transmission of SARS-CoV-2 from infected people to others is suggested based on epidemiology and clinical evidence [8,9], with even asymptomatic infected individuals suggested of being capable of transmitting the virus [10,11]
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