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

Irwin, Natalie; Murray, Lyle; Ozynski, Benjamin; Richards, Guy A; Paget, Graham; Venturas, Jacqueline; Kalla, Ismail; Diana, Nina; Mahomed, Adam; Zamparini, Jarrod

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.