Clinical evaluation of single-swab sampling for rapid COVID-19 detection in outbreak settings in Dutch nursing homes

Key summary points Aim To assess whether in the nursing home (NH) setting a single-swab sampling method, in which one swab can be used to perform both the Ag-RDT and RT-PCR, can be used for rapid COVID-19 detection during an outbreak. Findings In the NH setting, the single-swab method had a sensitivity of 51% and a specificity of 89% compared to RT-PCR, which was lower than in the laboratory setting (69% and 100%, respectively). During focus groups, both advantages and disadvantages of the single-swab method emerged. Message For the vulnerable NH residents, it is important to find the right balance between effective testing policy and the burden this imposes. Supplementary Information The online version contains supplementary material available at 10.1007/s41999-021-00584-3.
Purpose To assess whether one swab can be used to perform both the antigen-detection rapid diagnostic test (Ag-RDT) and reverse transcriptase polymerase chain reaction (RT-PCR) for COVID-19 detection during an outbreak in the nursing home (NH) setting. Methods The single-swab method (SSM), where the Ag-RDT is performed with the transport medium used for RT-PCR, was evaluated in three Dutch NHs and compared to the laboratory setting. We collected Ag-RDT and RT-PCR results, NH resident characteristics and symptomatology. In addition, two focus groups were held with the involved care professionals to gain insight into the feasibility of the SMM in the NH setting. Results In the NH setting, the SSM had a sensitivity of 51% and a specificity of 89% compared to RT-PCR. These were lower than in the laboratory setting (69% and 100% respectively). Yet, when stratified for cycle threshold values, the sensitivity became comparable between the settings. Symptoms occurred more frequent in the Ag-RDT+ group than Ag-RDT− group. Resident characteristics did not differ between these groups. Based on the focus groups, the SSM was feasible to perform if certain requirements, such as availability of staff, equipment and proper training, were met. However, the rapid availability of the test results were perceived as a dilemma. Conclusion The advantages and disadvantages need to be considered before implementation of the SSM can be recommended in the NH setting. For the vulnerable NH residents, it is important to find the right balance between effective testing policy and the burden this imposes. Supplementary Information The online version contains supplementary material available at 10.1007/s41999-021-00584-3.