The Difference in Immunoglobulin G Levels Between Outpatients and Inpatients With COVID-19

Background: Coronavirus disease 2019 (COVID-19) has rapidly become a pandemic since it was first reported in late December 2019. Serological reports are of great value to medical specialists in developing health policies. The detection of Immunoglobulin G (IgG) level in COVID-19 patients can specify a preclinical infection or previous exposure to the virus. Objective: This study aims to assess the IgG rate in patients with COVID-19. Methods: This is a cross-sectional study on 172 patients with confirmed COVID-19 (having positive PCR test) in Qazvin, Iran in 2020, including 86 inpatients and 86 outpatients. In order to measure the IgG levels, the serum samples were collected 3-5 weeks after onset of their clinical symptoms. Data were statistically analyzed in SPSS software v. 20, considering the significance level of P<0.05. Results: Of 172 patients, 81(94.2%) inpatients and 74(86%) outpatients tested positive for IgG, while 5(5.8%) inpatients and 10(11.6%) outpatients tested negative for IgG. The mean IgG level in inpatients was significantly higher than in outpatients (P<0.001) 3-5 weeks after a positive PCR test. Conclusion: The amounts of IgG in the sera of COVID-19 patients 3-5 weeks after the onset of symptoms can help health care authorities develop policies and control strategies by determining the burden of disease, monitoring the spread of disease, and estimating the epidemiological factors.