The Relationship between Serological Testing, Demographics, Clinical Presentation and RT-PCR Testing for COVID-19

Serological tests provide an important tool to diagnose previous exposure to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein we describe the relationship between the demographics, clinical characteristics, and molecular investigations and the presence of coronavirus disease 2019 (COVID-19) antibodies.

Three hundred and four participants, living in Gauteng, South Africa, were screened for COVID-19 antibodies between September 12, and December 12, 2020. Indications for serological testing included previous infection (n = 45, 14.80%), World Health Organization (WHO) symptoms (n = 122, 40.13%), positive household contact (n = 40, 13.16%), and/or positive close non-household contact (n = 80, 26.32%).

There were 58 (19.08%) positive rapid antibody tests. Risk factors associated with a positive rapid antibody test included WHO symptoms, namely fever/chills (odds ratio [OR] 3.50, 95% confidence interval [CI] 1.50 to 8.19), loss of taste or smell (OR 8.66, 95% CI 3.27 to 22.94), and the presence of a household contact (OR 3.66, 95% CI 1.59 to 8.40).

The findings support the measures implemented to reduce the spread of infection.