Objective To assess the readability of the informed consent forms from the phase III COVID-19 vaccine trials conducted in the United States. Patients English consent forms utilized for patients in phase III COVID-19 vaccine clinical trials. Consent forms were obtained in October 2020. Methods Using Microsoft Word tools, we analyzed the readability (i.e., the ease of reading) of written consent forms and informational documents from phase III COVID-19 vaccine clinical trials in the United States from the following manufacturers: AstraZeneca, Moderna, Pfizer, Johnson & Johnson, and Novavax. Results Due to low readability and several format factors, this study determined that none of the consent forms or informational documents from the recent phase III COVID-19 vaccine clinical trials conducted in the United States met readability standards at the recommended 7 th grade readability level for the average vaccine research volunteer in any readability category. The average English-speaking vaccine-trial volunteer would have great difficulty comprehending the information provided in the consent forms and informational documents. To ensure that study subjects receive and fully comprehend information regarding a clinical study and can provide reliable consent, greater attention should be given to the development and use of simplified consent forms, multimedia formatting, personal discussion, and comprehension assessments.

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