Procalcitonin is a marker of bacterial infection which can be measured in the blood. It is a relatively new test which is already used in some hospitals, mostly to help doctors understand what is causing severe infections.
We used this test during the COVID-19 pandemic because some data suggested it shows how unwell someone might become in the early stages of COVID-19. It could also be useful to identify patients who have bacterial infections on top of the COVID-19 disease or give doctors a measure of whether the disease is becoming more severe.
We want to find out whether this test was accurate, and whether it added important information beyond some of the more commonplace tests we do in the hospital. Understanding this will help us decide whether we should carry on doing the test in the future.