SARS-CoV-2 IgM and IgG serology and clinical outcomes in COVID-19 patients

BackgroundThe SARS-CoV-2 virus has become pandemic for the last 2 years. Inflammatory response to the virus leads to organ dysfunction and death. Predicting the severity of inflammatory response helps in managing critical patients using serology tests IgG and IgM. We conducted a longitudinal study to correlate serum SARS-CoV-2 IgM and IgG serology with clinical outcomes in COVID-19 patients. MethodsWe analyzed patient data from March to December of 2020 for those who were admitted at AIIMS Rishikesh. Clinical and laboratory data of these patients were collected from the e-hospital portal and analysed. Correlation was seen with clinical outcomes and was assessed using MS Excel 2010 and SPSS software. ResultsOut of 494 patients, the mean age of patients was 48.95 {+/-} 16.40 years and there were more male patients in the study (66.0%). The patients were classified into 4 groups; mild-moderate 328 (67.1%), severe 131 (26.8%) and critical 30 (6.1%). The mean duration from symptom onset to serology testing was 19.87 {+/-} 30.53 days. In-hospital mortality was observed in 25.1% patients. The seropositivity rate (i.e., either IgG or IgM >10 AU) was 50%. There was a significant difference between the 2 groups in terms of IgM Levels (AU/mL) (W = 33428.000, p = <0.001) and IgG Levels (AU/mL) (W = 39256.500, p = <0.001), with the median IgM/ IgG Levels (AU/mL) being highest in the RT-PCR-Positive group. There was no significant difference between the groups in terms of IgM Levels and IgG levels with all other clinical outcomes (disease severity, septic shock, Intensive care admission, mechanical ventilation and mortality). ConclusionSerology (IgM and IgG) levels are high in RTPCR positive group compared to clinical COVID-19. However, serology cannot be useful for the prediction of disease outcomes except few situations. The study also highlights the importance of doing serology at a particular time as antibody titres vary with the duration of the disease.