Table 1.

Search strategies used to retrieve related documents.

Search syntax in PubMed database

(covid‐19 OR Sars‐cov‐2 OR coronavirus OR Cov‐19 OR 2019‐ncov OR covid19 OR “covid‐19 pandemic”) AND (“clinical research” [tiab] OR “clinical study” [tiab] OR “clinical trial*“ [tiab]) AND (barriers[tiab] OR obstacles[tiab] OR challenges[tiab] OR difficulties[tiab] OR facilitators[tiab] OR enablers[tiab]) AND 2019/01/01:2023/01/01[dp]

Search syntax in Web of Science (WOS) citation index expanded (SCI‐EXPANDED)

(ALL = (covid‐19 OR sars‐cov‐2 OR coronavirus OR Cov‐19 OR 2019‐ncov OR covid19 OR “covid‐19 pandemic”) AND TS = (“clinical research” OR “clinical study” OR “clinical trial*“) AND TS = (barriers OR obstacles OR challenges OR difficulties OR facilitators OR enablers) AND PY = (2019‐2023))