Helmut Nyawale (Würzburg / DE; Mwanza / TZ), Isabell Wagenhäuser (Würzburg / DE), Julia Reusch (Würzburg / DE), Juliane Mees (Würzburg / DE), Salim Masoud (Dar es Salaam / TZ), Doreen Kamori (Dar es Salaam / TZ), Nyambura Moremi (Dar es Salaam / TZ), Stephen Mshana (Mwanza / TZ), Manuel Krone (Würzburg / DE), Mariam Mirambo (Mwanza / TZ)
Question: The infection with severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) and the development of coronavirus disease 2019 (COVID-19) represents a global health care challenge. World Health Organization (WHO) insists on the use of diagnostic tools which are affordable, and easy to perform with high sensitivity and specificity. WHO suggests the use of SARS-CoV-2 antibody-rapid diagnostic tests in low and middle income countries (LMIC) for sero-epidemiological studies that meet the least performance prerequisites of ≥ 80% sensitivity and ≥ 97% specificity.
We, therefore, validated a SARS-CoV-2 antibody rapid detection test against a reference standard for antibody diagnostics, the Enzyme-linked Immunosorbent Assay (ELISA) performance characteristics
Methods: We collected blood specimens from consented participants during regional wide serological survey in three districts in Mwanza; Ukerewe, and Magu/Tanzania. The blood samples were tested directly after sample asservation for SARS-CoV-2 IgG on site using RADI COVID-19 IgG rapid test kits (KH Medics Limited). The results were compared to aquantitative ELISA (SERION ELISA agile SARS-CoV-2 IgG) performed from frozen samples. Data management and analysis was done using STATA version 12.
Results: A total of 710 samples were evaluated for performance characteristics of the test. Out of the 368 samples which were positive in the RADI COVID-19 IgG rapid test kits, 312 were concordant positive for both RADI rapid test and Serion IgG ELISA, thus, giving a sensitivity of 84.7% (95 CI, 81.2-88.3%). Out of 342 samples which tested negative for the RADI rapid test, 333 were concordant negative, giving a specificity of 97.4%. The positive predictive values and negative predictive values of the tests were 97.2% and 85.6% respectively.
Previous history of fever was significantly associated with false positive RADI COVID-19 IgG test results (p=0.012).
Conclusions: The performance characteristics of the RADI COVID-19 IgG rapid test kits compared to the Serion IgG ELISA are within recommended WHO performance characteristics which can still be used for serological surveys in African settings.