Authors : Ranjana Hawaldar, Ranjana Hawaldar, Sadhna Sodani, Sadhna Sodani, Varsha Sodani, Varsha Sodani, R K Sodani, R K Sodani
DOI : 10.18231/j.jchm.2021.009
Volume : 8
Issue : 1
Year : 2021
Page No : 40-44
Introduction: The COVID-19 pandemic has raged on for about a year. In India, 10,880,603 individuals were infected as on 12th February 2021. Cross-sectional population seroprevalence data is crucial to plan vaccination strategies to cover the most susceptible sub-populations beyond the prioritized groups. Notably, a seroprevalence data based on measurement of clinically relevant neutralizing antibodies to SARS-CoV-2
infection, gives a legitimate estimate of the extent of immunity for baselining a population.
Objectives: This study examines the cross-sectional seroprevalence of anti-SARS-CoV-2 neutralizing IgG antibodies in 1561 individuals from city of Indore in India, using first and by far the only SARS-CoV-2 IgG assay approved under EUA by the USFDA for semiquantitative measurements.
Materials and Methods: A cross-sectional retrospective study was conducted using the serum samples obtained from 1561 between 7th September 2020 to 9th December 2020. Siemens Healthineers COV2G assay that detects neutralizing IgG against the S1-RBD (receptor binding domain of spike protein subunit 1 antigen was selected to be used in this study. Participants were tested for seroconversion by the measurement of anti-SARS-CoV-2 S1 RBD IgG antibodies on Atellica Solution, and were categorized as seropositive if SARS-CoV-2 antibodies were detected at a threshold of > 1.0 index value; or seronegative if SARS-CoV-2 antibodies were below the threshold.
Results: We report an overall seroconversion rate of 33% across our cohort. 50% of the symptomatic population demonstrated seropositivity. 30% of asymptomatic population also demonstrated seropositivity.
Out of 194 individuals with positive RT-PCR test, 52% [n=101] were sero positive. And of the 196 individuals with negative RT-PCR test, 34% [n=66] were sero positive.
Conclusion: This serosurveillance study highlights the importance of measuring the prevalence of neutralizing antibody titers in general population across disparate groups. Along with other studies, may subsequently guide policy making and developing vaccination strategies for those other than the prioritized groups. Insight into the current seroprevalence of SARS-CoV-2 antibodies within this cohort is of direct relevance as a reference point for future community serological surveys.
Keywords: Serosurveillance, S1RBD IgG, SARSCoV2, RT-PCR, COV2G assay.