LAUSR

Objective: COVID-19 caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), utilises the catalytic site of membrane-bound angiotensin converting enzyme 2 (ACE2) for cell entry It is thought that endocytosis of ACE2 results in a decrease in membrane bound ACE2 expression, and disruption of the local tissue renin angiotensin system protection In this study, we hypothesised that SARS-CoV-2 infection would be associated with shedding of ACE2 leading to increased plasma ACE2 activity Design and method: Australians aged >18 years (n=66) who had recovered from SARS-CoV-2 infection (positive result by PCR testing) and uninfected controls (n=70) were recruited Serial samples were available in 23 recovered SARS-CoV-2 patients Plasma ACE2 activity was measured using a fluorescent substrate-based assay and levels were compared using the Mann-Whitney or Kruskal-Wallis test Serial ACE2 activity were analysed using the Friedman test for repeated measures Post-hoc analysis was performed with a Bonferroni correction Two-tailed P-values 0 05) in the proportion of hypertension, obesity, diabetes, cardiovascular disease, or use of anti hypertensive, lipid lowering, and anti-platelet medications between the controls and SARSCoV-2 patients Plasma ACE2 activity at median 35 days post-infection [interquartile range 30-38 days] was 97-fold higher in SARS-CoV-2 patients compared to controls (5 8 [2-11 3] vs 0 06 [0 02-2 2] pmol/min/ml, p0 05) Conclusions: Plasma ACE2 activity is elevated after SARS-CoV-2 infection and remains elevated post-infection Our findings indicate the need for ongoing investigation to determine if ACE2 levels identify people at risk of prolonged illness following COVID-19