On the sensitivity and specificity of postmortem upper respiratory tract testing for SARS-CoV-2

Abstract

Background: Postmortem testing can improve our understanding of the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) if sufficiently sensitive and specific. Methods: We investigated the postmortem sensitivity and specificity of reverse transcriptase polymerase chain reaction (PCR) testing on upper respiratory swabs using a dataset of everyone tested for SARS-CoV-2 before and after death in England, 1 March to 29 October 2020. We analyzed sensitivity in those with a positive test before death by time to postmortem test. We developed a multivariate model and conducted time-to-negativity survival analysis. For specificity, we analyzed those with a negative test in the week before death. Results: Postmortem testing within a week after death had a sensitivity of 96.8% if the person had tested positive within a week before death. There was no effect of age, sex, or specimen type on sensitivity, but individuals with coronavirus disease 2019 (COVID-19)-related codes on their death certificate were 5.65 times more likely to test positive after death (95% confidence interval, 2.31-13.9). Specificity was 94.2%, increasing to 97.5% in individuals without COVID-19 on the death certificate. Conclusion: Postmortem testing has high sensitivity (96.8%) and specificity (94.2%) if performed within a week after death and could be a useful diagnostic tool.