Persistence of SARS-CoV-2 Antibody Response across Diverse Clinical Settings in Oman: Insights from a Prospective ELISA-based Study

Objectives: The durability of SARS-CoV-2 antibody response varies with disease severity [1]. Comparative data across diverse clinical settings in the Gulf region are limited. This study assessed the persistence of SARS-CoV-2 immunoglobulin G (IgG) antibodies over 6 months among hospitalized patients, outpatients, and healthcare workers (HCWs). 

Methods: In this prospective cohort study, 356 confirmed COVID-19 cases (123 inpatients, 113 outpatients, and 120 HCWs) were enrolled. Serum IgG titers were measured using enzyme-linked immunosorbent assay (ELISA) at baseline (≤14 days post-symptom onset), 4-6 weeks, 3 months, and 6 months post-infection. Longitudinal antibody dynamics were analyzed using a linear mixed-effect model adjusting for patient group, age, comorbidities, and symptoms. 

Results: Inpatients were older, male, and had more comorbidities, including obesity 54.5% (67 of 123), diabetes mellitus 39% (48 of 123), and hypertension 39.8% (49 of 123), compared with outpatients and HCWs. Peak antibody titers were reached at 4-6 weeks, with gradual decline over the 6-month period after initial infection across all groups (P <0.001). Inpatients demonstrated significantly higher IgG titers at all time points (P <0.001). 

Conclusions: Severe COVID-19 infection, older age, and comorbidities were linked to stronger, more durable IgG responses. These findings provide essential baseline data on post–COVID-19 immunity in the Gulf region during early pandemic.