The recent pandemic of Coronavirus disease 2019 (COVID-19) has markedly affected the health care system and society worldwide. Now, we have to carefully consider the balance between ethics and regulations to continue ongoing clinical trials and practical mitigations to rescue study participants.

Indeed, securing the safety of the study participants should come first, as stated in the Pharmaceuticals and Medical Devices Agency (PMDA), Japan Pharmaceutical Manufacturers Association (JPMA) and U.S. Food and Drug Administration (FDA) guidelines [1,2,3]. Securing the safety of health care providers and study-related personnel is also important. What are the ethical considerations regarding continuing ongoing clinical trials in such an emergency? One of the requirements to justify the continuation of ongoing clinical trials is that the study participants are not exposed to the additional risk of being infected by COVID-19. To enable this, satisfactory actions are required to minimize the frequency of actual study site visits as much as possible in order for subjects to stay home, and be safe and well. Examples of practical mitigations in clinical trials collecting electronic data, such as continuous glucose monitoring (CGM), and the pros and cons are listed in Table 1.

Table 1 Examples of practical mitigations for ongoing clinical trials during the COVID-19 pandemic

It is possible that some of the study participants will decide to withdraw consent to be involved in the clinical trials because of the COVID-19 pandemic. Such decisions must be respected; however, it is important to keep the records due to the COVID-19 pandemic for later purposes. The same applies to all deviations such as the delay of study visits or missing data due to the COVID-19 pandemic.

Clinical trials require a great amount of time and resources to prepare, execute, and analyze, but the safety of study participants, health care providers, and study-related personnel must be secured. Moreover, if continuation of the ongoing clinical trial can be ethically justified after sufficient mitigations, endeavors to complete the clinical trial should be encouraged.