SARS-CoV-2 seroprevalence in patients with autoimmune rheumatic diseases versus family controls: a multi-city cross-sectional survey

There is uncertainty regarding the effect of the SARS-CoV-2 infection on patients with autoimmune rheumatic diseases (AIRD) who are on immunosuppressive drugs. We did a multicity cross-sectional seroprevalence study conducted in five different cities in India before COVID-19 immunization. Patients with a diagnosis of AIRD and DMARDs were included. Relatives of the patients, preferably staying in the same household with no known rheumatic diseases served as controls. Serum IgG antibodies to SARS-CoV-2 Receptor Binding Domain (RBD) of the spike protein and nucleoprotein (NP) were assayed in eight hundred and eighty nine sera (subjects with disease = 379 and in subjects without disease = 510). IgG antibodies to either RBD and/or NP were positive in 135 (36%) subjects with AIRD as compared to 196 (38%) controls. The seroprevalence of anti-RBD and anti-NP varied between different cities but was not significantly different between subjects with and without disease in Mumbai, Ahmedabad, Bengaluru and Bhubaneswar. However, the occurrence of IgG antibodies to RBD was significantly (p < 0.05) lower in subjects with disease (28/65;43%) as compared to subjects without disease (42/65;65%) in Kolkata, where the positivity rate was lower in connective tissue disease group than in inflammatory arthritis group. Overall, patients with rheumatic diseases on DMARDs have IgG antibodies to RBD and NP of SARSCoV-2 at a comparable level with that of subjects without disease, but the level of antibodies to RBD is lower in patients with connective tissue disease on immunosuppressive drugs in one centre.