Table 1.

COVID-19-related factors and examples of their potential impacts on clinical trials.

Factor	Example of impact/risk
Quarantines, travel limitations, participant unable/unwilling to travel to site due to personal pandemic-related reasons, site closures or reduced availability of site staff	Missed or delayed visits and assessments Inability to access study treatment Loss to follow-up Longer query response time Different investigators/different measurement modalities Delayed site monitoring Delayed patient enrolment
Interruptions to supply chain of experimental drug and/or other medications	Missed dosing of study drugs Changes in non-COVID-19 concomitant medications
Alternative administration of drug	Increased risk of dosing errors Lack of equivalence of methods of administration
Alternative collection of specimens	Challenges in reconciliation and verification
Alternative data collection	Lack of exchangeability of methods
COVID-19 infection/treatment	Temporary/permanent interruption of study treatment and/or study participation Potential effect on efficacy endpoints/estimands/safety Interactions of COVID-19 concomitant medications with study drugs