Age significantly influences the sensitivity of SARS-CoV-2 rapid antibody assays

Irwin, N.; Murray, L.; Ozynski, B.; Richards, G. A.; Paget, G.; Venturas, J.; Kalla, I.; Diana, N.; Mahomed, A.; Zamparini, J.

BACKGROUND Point of care serological assays are a promising tool in COVID-19 diagnostics but do have limitations. This study evaluated the sensitivity of five rapid antibody assays and explored factors influencing their sensitivity to detect SARS-CoV-2-specific IgG and IgM antibodies. METHODS Finger-prick blood samples from 102 participants, within two to six weeks of PCR-confirmed COVID-19 diagnosis, were tested for IgG and IgM on five rapid serological assays. The assay sensitivities were compared, and patient factors evaluated in order to investigate potential associations with assay sensitivity. RESULTS Sensitivity ranged from 36% to 69% for IgG and 13% to 67% for IgM. Age was the only factor significantly influencing the likelihood of a detectable IgG or IgM response. Individuals aged 40 years and older had an increased likelihood of a detectable IgG or IgM antibody response by rapid antibody assay. CONCLUSION Rapid serological assays demonstrate significant variability when used in a real-world clinical context. There may be limitations in their use for COVID-19 diagnosis amongst the young.