Seroconversion in COVID-19: a Tool for Risk Assessment in Frontline COVID Warriors

Objectives : To analyse the seroconversion rate of COVID-19 antibody and its association with risk of future infection in frontline COVID warriors. Methodology: Longitudinal cohort study conducted in 218 frontline COVID warriors. Baseline anti-spike IgG antibodies estimated and followed up for RT-PCR positive infection. Seropositive subjects were followed up with serial titres at 4 visits upto 6 months. Statistical analysis: SPSS ver. 22.0 used employing chi-square test for association of seropositivity with RT-PCR outcome. Antibody kinetics was calculated using a mathematical linear regression model. Incidence rate was calculated per 10000 person years at risk and relative risk was calculated. Results: IgG positivity was seen in 93.8% subjects who had COVID infection in past 30 days. Significantly higher incidence of infection was observed in seronegative subjects who were at 10 times higher risk of infection than seropositive cases (p