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

Hall, Jennifer A; Harris, Ross J; Emmett, Hannah E; Lowe, Belinda; Singanayagam, Anika; Twohig, Katherine A; Zaidi, Asad; Kall, Meaghan; Zambon, Maria; Dabrera, Gavin

BACKGROUND: Post-mortem testing can improve our understanding of the impact of SARS-CoV-2 if it is sufficiently sensitive and specific. METHODS: We investigated the post-mortem sensitivity and specificity of reverse transcriptase PCR testing on upper respiratory swabs using a dataset of everyone who had been tested for SARS-CoV-2 before and after death in England between 1 (st) March-29 (th) October 2020. We analysed sensitivity in those who had a positive test before death by time to post-mortem test. We developed a multivariate model and conducted time-to-negativity survival analysis. For specificity we analysed those with a negative test in the week before death. RESULTS: Post-mortem 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 COVID-19-related codes on their death certificate were 5.65 times more likely to test positive after death (95%CI 2.31,13.9). Specificity was 94.2%, increasing to 97.5% in individuals without COVID-19 on the death certificate. CONCLUSION: Post-mortem testing has high sensitivity (96.8%) and specificity (94.2%) if performed within a week after death and could be a useful diagnostic tool.