Table 1:

Main characteristics of the studies

Author, year	Origin	Study duration	Study design	Sample size	Sampling	Main findings
Medidata, 2020 [4]	Multicenter	April 23rd, to April 29th, 2020	Cross-Sectional	1,030 subjects	Convenience sampling	For 69% of respondents, COVID-19 has affected their ability to conduct ongoing trials, while 78% believe that COVID-19 has impacted the initiation of new trials. The top four concerns based on the weighted average of the answers were: ability to enroll patients (3.73); ability to recruit patients (3.66); financial implications for cancelled studies (3.42); and financial implication from delayed milestones (3.29).
Medidata, 2020 [5]	Multicenter	March, April and the first two weeks of May	Cross-Sectional	4,667 studies and 186,807 study-sites	Convenience sampling	A 74% decrease in the average number of new patients entering trials per study-site year-over-year during the first two weeks of May compared to last year. Shows the pandemic continues to have an effect on trial activity and new patients entering trials.
Upadhaya, 2020 [6]	Multicenter	March 23rd and April 3rd 2020	Cross-Sectional	36 subjects	Convenience sampling	Patient enrolment in active oncology clinical trials was negatively affected at the time of the survey. Asia [60%], United States [20%] and Europe [14%] were continuing to enrol patients at the usual rate.
Waterhouse, 2020 [7]	USA	March 24th to 30th, 2020	Cross-Sectional	32 subjects	Convenience sampling	Over half of the respondents (54.8%) observed a decrease in patient’s willingness to come to their site and cited the staff time needed to conduct telehealth visits as a significant challenge. 51.6% noted that limited availability of ancillary services was challenging. Time spent in discussion with sponsors, CROs, and IRBs about modifying trial procedures also presented a challenge for 51.6% participants.
Medidata, 2020 [8]	Multicenter	June 15, July 13, 2020	Cross-Sectional	1,030 subjects	Convenience sampling	In comparison to the pre- COVID-19 baseline (October 31), globally there is around 30% decrease in enrollment of new subjects entering trials by the end of June which was previously higher in April, 2020 (~70% drop). Currently, within different geographic regions, a marked variability has been observed regarding the extent and timing of recovery of patients due to continued fluctuation in the COVID-19 cases, and adoption of regulations over the time.
Medidata, 2020 [9]	Multicenter	July 13 - August 12, 2020	Cross-Sectional	5,089 studies and 194,506 study sites.	Convenience sampling	By the end of July 2020, there is an improvement in new subject enrollment in clinical trials per study-site worldwide with around -30% for the month of June in comparison to -6% at baseline (pre-COVID-19). The negative effects of COVID-19 on new patients enrollment in clinical trials is expected to continue at different times and varying degree throughout the world which is likely understated.