Objectives Adherence to pharmacological intervention in clinical trials is crucial for the correct estimation of medication effect and side effects. The Template for Intervention Description and Replication (TIDieR) - a 12-item extension of the Consolidated Standards of Reporting Trials (CONSORT) reporting guidelines - includes two items (11 and 12) that address intervention adherence reporting in trial publications. This study sought to assess compliance with TIDieR items 11 and 12 of selected SARS-CoV-2 trial publications.

Method The corpus of SARS-CoV-2 related randomized controlled trials (RCTs) published in the Annals of Internal Medicine, BMJ, JAMA, The Lancet, and The New England Journal of Medicine in 2021 were assessed for their compliance with TIDieR items 11 and 12. Items 11 and 12 begin with a conditional requirement: ‘if intervention adherence or fidelity was assessed…’. When this conditional requirement was unmet, the item was reported as ‘not applicable’. Item 11 was assessed in two parts; 11a) how intervention adherence was assessed and 11b) if any strategies were used to maintain or improve fidelity, how intervention adherence was maintained or improved. Where a strategy was not used to maintain or improve fidelity, item 11b was reported as ‘not applicable’. Raw and proportional (weighted) adherence were calculated.

Results We found 75 eligible RCTs of which 28 (37.3%) reported results related to SARS-CoV-2 vaccinations. Compliance with item 11a and 12 could be assessed in 71 of these 75; only 7 RCTs had a fidelity strategy to assess compliance with item 11b. 37 (52.1%) of 71 RCTs were compliant with reporting of item 11a (how intervention adherence was assessed). 3 (42.9%, CI 9% - 81.6) of the 7 studies with a fidelity strategy complied with item 11b reporting. 70 of 71 RCTs complied with reporting of item 12. 1 of 71 (1.4%, 95% confidence interval [CI] 0% – 7.6%) RCTs fully complied with TIDieR items 11a, 11b and 12. Compliance varied across journals.

Conclusions Despite the endorsement of CORSORT, SARS-CoV-2 related RCTs published in high impact medical and health journals had variable compliance with intervention adherence reporting. The implications for interpretation, application and replication of findings based on these publications warrant consideration.