Correlation of serum SARS-CoV-2 IgM and IgG serology and clinical outcomes in COVID-19 patients:Experience from a tertiary care centre

BACKGROUND The severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)virus has become a 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.AIM To investigate the correlation of the serology(IgM and IgG)with reverse transcriptase polymerase chain reaction(RT-PCR)status,disease severity[mild to critical],intensive care unit(ICU)admission,septic shock,acute kidney injury,and in-hospital mortality.METHODS We conducted a longitudinal study to correlate serum SARS-CoV-2 immunoglobulin M(IgM)and immunoglobulin G(IgG)serology with clinical outcomes in coronavirus disease 2019(COVID-19)patients.We analyzed patient data from March to December 2020 for those who were admitted at All India Institute of Medical Sciences Rishikesh.Clinical and laboratory data of these patients were collected from the e-hospital portal and analyzed.A correlation was seen with clinical outcomes and was assessed using MS Excel 2010 and SPSS software.RESULTS Out 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 as 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 d.In-hospital mortality was observed in 25.1%of patients.The seropositivity rate(i.e.,either IgG or IgM>10 AU)was 50%.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),were highest in the RT-PCR-Positive group compared to RT-PCR-Negative clinical COVID-19.There was no significant difference between the two groups in terms of all other clinical outcomes(disease severity,septic shock,ICU admission,mechanical ventilation,and mortality).CONCLUSION The study showed that serology levels are high in RT-PCR positive group compared to clinical COVID-19.However,serology cannot be useful for the prediction of disease outcomes.The study also highlights the importance of doing serology at a particular time as antibody titers vary with the duration of the disease.In week intervals there was a significant correlation between clinical outcomes and serology on week 3.

Human IgM and IgG Responses to an Inactivated SARS-CoV-2 Vaccine

Objective:The ongoing COVID-19 pandemic warrants accelerated efforts to test vaccine candidates.To explore the influencing factors on vaccine-induced effects,antibody responses to an inactivated SARS-CoV-2 vaccine in healthy individuals who were not previously infected by COVID-19 were assessed.Methods:All subjects aged 18-60 years who did not have SARS-CoV-2 infection at the time of screening from June 19,2021,to July 02,2021,were approached for inclusion.All participants received two doses of inactivated SARS-CoV-2 vaccine.Serum IgM and IgG antibodies were detected using a commercial kit after the second dose of vaccination.A positive result was defined as 10 AU/mL or more and a negative result as less than 10 AU/mL.This retrospective study included 97 infection-naive individuals(mean age 35.6 years;37.1%male,62.9%female).Results:The seropositive rates of IgM and IgG antibody responses elicited after the second dose of inactivated SARS-CoV-2 vaccine were 3.1%and 74.2%,respectively.IgG antibody levels were significantly higher than IgM levels(P<0.0001).Sex had no effect on IgM and IgG antibody response after the second dose.The mean anti-IgG level in older persons(≥42 years)was significantly lower than that of younger recipients.There was a significantly lower antibody level at>42 days compared to that at 0-20 days(P<0.05)and 21-31 days(P<0.05)after the second dose.Conclusion:IgG antibody response could be induced by inactivated SARS-CoV-2 vaccine in healthy individuals(>18 years),which can be influenced by age and detection time after the second dose of vaccination.