Study Design, Randomization, and Volunteers

This clinical trial (clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT04651790","term_id":"NCT04651790"}}NCT04651790) was conducted in Chile at 8 different sites. The study protocol was performed according to the current Tripartite Guidelines for Good Clinical Practices, the Declaration of Helsinki [15], and local regulations. The trial protocol was reviewed and approved by the Institutional Scientific Ethical Committee of Health Sciences, Pontificia Universidad Católica de Chile (#200708006). Trial execution was approved by the Chilean Public Health Institute (#24204/20). Written informed consent was obtained from each volunteer before enrollment. The study included healthy Chilean adults aged ≥18 years. Volunteers were inoculated with either 2 doses of CoronaVac or placebo separated by 2 weeks.

A complete list of inclusion/exclusion criteria is provided in the annexed study protocol. Volunteers were randomly assigned to immunization with CoronaVac or injection with placebo in a 1:1 ratio. A subgroup of volunteers was assigned to the immunogenicity arm and randomly received CoronaVac or placebo (3:1 ratio). Randomization was done using a sealed enveloped system integrated into the electronic case report forms in the OpenClinica platform. To collect adverse events (AEs), volunteers were instructed and trained to log in information on the platform until 28 days after the second dose at the same hour each day. Local and systemic symptoms were requested for 7 days after each dose or until they ceased. Other AEs, drugs used, severe adverse events (SAEs), events of special interest, and symptoms of SARS-CoV-2 were also requested until the end of the study. Daily reminders were sent via email and SMS until 28 days after the second dose and then weekly until the end of the study. Table 1 summarizes the characteristics of the volunteers, and Figure 1 shows the study profile.

Characteristics of the Volunteers at Baseline

P values are for comparison between total numbers in each characteristic.

Study profile. Recruitment of volunteers for the phase 3 clinical trial as of February 10, 2021.