Sensitivity of SARS-CoV-2 RNA polymerase chain reaction using a clinical and radiological reference standard.

OBJECTIVES: Diagnostic tests for SARS-CoV-2 are important for epidemiology, clinical management, and infection control. Limitations of oro-nasopharyngeal real-time PCR sensitivity have been described based on comparisons of single tests with repeated sampling. We assessed SARS-CoV-2 PCR clinical sensitivity using a clinical and radiological reference standard. METHODS: Between March-May 2020, 2060 patients underwent thoracic imaging and SARS-CoV-2 PCR testing. Imaging was independently double- or triple-reported (if discordance) by blinded radiologists according to radiological criteria for COVID-19. We excluded asymptomatic patients and those with alternative diagnoses that could explain imaging findings. Associations with PCR-positivity were assessed with binomial logistic regression. RESULTS: 901 patients had possible/probable imaging features and clinical symptoms of COVID-19 and 429 patients met the clinical and radiological reference case definition. SARS-CoV-2 PCR sensitivity was 68% (95% confidence interval 64-73), was highest 7-8 days after symptom onset (78% (68-88)) and was lower among current smokers (adjusted odds ratio 0.23 (0.12-0.42) p < 0.001). CONCLUSIONS: In patients with clinical and imaging features of COVID-19, PCR test sensitivity was 68%, and was lower among smokers; a finding that could explain observations of lower disease incidence and that warrants further validation. PCR tests should be interpreted considering imaging, symptom duration and smoking status.

Pneumocystis pneumonia, a COVID-19 mimic, reminds us of the importance of HIV testing in COVID-19.

While clinical environments are highly focused on COVID-19, reports of missed or delayed treatment for conditions that imitate COVID-19, such as pneumonia caused by the fungus Pneumocystis jirovecii, are emerging. Given the uncertain spectrum of COVID-19 presentations and variable sensitivity of laboratory tests for SARS-CoV-2, there is a risk that, without a high index of suspicion, alternative aetiologies may be overlooked while pursuing a diagnosis of COVID-19. The British HIV Association has been calling for the inclusion of HIV testing in all patients admitted to hospital with suspected COVID-19. In this article we reflect on the importance of including HIV testing to prevent avoidable morbidity and mortality in our patients.

Is continuous positive airway pressure (CPAP) a new standard of care for type 1 respiratory failure in COVID-19 patients? A retrospective observational study of a dedicated COVID-19 CPAP service.

The aim of this case series is to describe and evaluate our experience of continuous positive airway pressure (CPAP) to treat type 1 respiratory failure in patients with COVID-19. CPAP was delivered in negative pressure rooms in the newly repurposed infectious disease unit. We report a cohort of 24 patients with type 1 respiratory failure and COVID-19 admitted to the Royal Liverpool Hospital between 1 April and 30 April 2020. Overall, our results were positive; we were able to safely administer CPAP outside the walls of a critical care or high dependency unit environment and over half of patients (58%) avoided mechanical ventilation and a total of 19 out of 24 (79%) have survived and been discharged from our care.