Performance of an alternative RT-PCR procedure using residual sample from the Panbioâ„¢ Ag COVID-19 test

Castineiras, Terezinha Marta Pereira Pinto; Nascimento, Érica Ramos dos Santos; Faffe, Débora Souza; Galliez, Rafael Mello; Mariani, Diana; Leitão, Isabela de Carvalho; de Melo, Mayla Gabryele Miranda; Ferreira, Orlando Costa; Tanuri, Amilcar

INTRODUCTION: In the current standard of care (SoC) RT-PCR method for COVID-19, the patient's swab was extracted in viral transport media (VTM). For the Panbioâ„¢ COVID-19 Ag Rapid Test, the patient swab is flushed out in extraction buffer, of which a small fraction is used for testing, leaving more than half the sample unused. This study was designed to show that RT-PCR results from the residual sample of the Panbioâ„¢ COVID-19 Ag Rapid Test (called Novel RT-PCR) are not worse than the SoC RT-PCR result. METHODS: The study was performed using (1) dilution series of five patient samples, and (2) 413 patient samples comparing SOC versus Novel RT-PCR results. RESULTS: For the dilution series samples, all tested positive by both methods. The bias between Ct values of Novel RT-PCR and SoC RT-PCR did not exceed 3.00 Ct using primers N1 and N2. A total of 413 COVID symptomatic patients seeking COVID testing were tested, of which 89 patients tested positive and 324 tested negative with SoC RT-PCR. In 324 patients who tested negative with SoC RT-PCR, 323 tested negative with Novel RT-PCR, and one (1) tested positive. Out of 89 who tested positive with SoC RT-PCR, 80 tested positive with the Novel RT-PCR, and nine patients showed a negative test result. The Overall Percent Agreement for the 413 valid patient sample pairs was 97.5 [95% CI 97 to 98]. CONCLUSION: The study demonstrated that the performance of the Novel RT-PCR method is acceptable compared to the SoC RT-PCR method and can be a useful tool to perform RT-PCR without the need for new swab collections.