Reflexivity statement The authors include three females and eight males and span multiple levels of seniority. While three of the authors specialize in health care quality and health policy in China and West Pacific, the rest includes epidemiologists, economists, and medical staffs with expertise in sextually transmitted diseases, health economics, and global health in the Africa and Asia. All authors have extensive experience conducting fieldwork in developing countries, especially in China and India.

Large observational data networks that leverage routine clinical practice data in electronic health records (EHRs) are critical resources for research on COVID-19. Data normalization is a key challenge for the secondary use of EHRs for COVID-19 research across institutions. In this study, we addressed the challenge of automating the normalization of COVID-19 diagnostic tests, which are critical data elements, but for which controlled terminology terms were published after clinical implementation. We developed a simple but effective rule-based tool called COVID-19 TestNorm to automatically normalize local COVID-19 testing names to standard LOINC codes. COVID-19 TestNorm was developed and evaluated using 568 test names collected from eight healthcare systems. Our results show that it could achieve an accuracy of 97.4% on an independent test set. COVID-19 TestNorm is available as an open-source package for developers and as an online web application for end-users (https://clamp.uth.edu/covid/loinc.php). We believe it will be a useful tool to support secondary use of EHRs for research on COVID-19.