Safety and Non-Inferiority Evaluation of Two Immunization Schedules with an Inactivated SARS-CoV-2 Vaccine in Adults: A Randomized Clinical Trial

Katia Abarca*, Carolina Iturriaga, Marcela Urzúa, Nicole Le Corre, Augusto Pineda, Carolina Fernández, Angélica Domínguez, Pablo A. González, Susan M. Bueno, Paulina Donato, Pilar Espinoza, Daniela Fuentes, Marcela González, Paula Guzmán, Paula Muñoz Venturelli, Carlos M. Potin, Marcela Potin, Álvaro Rojas, José V. González-Aramundiz, Nicolás M.S. GálvezFrancisca Aguirre-Boza, Sofía Aljaro, Luis Federico Bátiz, Yessica Campisto, Mariela Cepeda, Aarón Cortés, Sofía López, María Loreto Pérez, Andrea Schilling, Alexis M. Kalergis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Several vaccines have been developed to control the COVID-19 pandemic. CoronaVac®, an inactivated SARS-CoV-2 vaccine, has demonstrated safety and immunogenicity, preventing severe COVID-19 cases. We investigate the safety and non-inferiority of two immunization schedules of CoronaVac® in a non-inferiority trial in healthy adults. A total of 2302 healthy adults were enrolled at 8 centers in Chile and randomly assigned to two vaccination schedules, receiving two doses with either 14 or 28 days between each. The primary safety and efficacy endpoints were solicited adverse events (AEs) within 7 days of each dose, and comparing the number of cases of SARS-CoV-2 infection 14 days after the second dose between the schedules, respectively. The most frequent local AE was pain at the injection site, which was less frequent in participants aged ≥60 years. Other local AEs were reported in less than 5% of participants. The most frequent systemic AEs were headache, fatigue, and myalgia. Most AEs were mild and transient. There were no significant differences for local and systemic AEs between schedules. A total of 58 COVID-19 cases were confirmed, and all but 2 of them were mild. No differences were observed in the proportion of COVID-19 cases between schedules. CoronaVac® is safe, especially in ≥60-year-old participants. Both schedules protected against COVID-19 hospitalization.

Original languageEnglish
Article number1082
Issue number7
StatePublished - 6 Jul 2022

Bibliographical note

Funding Information:
Acknowledgments: We would like to thank the Ministry of Health, Government of Chile; Ministry of Science, Technology, Knowledge, and Innovation, Government of Chile; and The Ministry of Foreign Affairs, Government of Chile and the Chilean Public Health Institute (ISP). We also thank the Vice Presidency of Research (VRI), the Direction of Technology Transfer and Development (DTD), the Legal Affairs Department (DAJ) of the Pontificia Universidad Católica de Chile. We are also grateful to the Administrative Directions of the School of Biological Sciences and the School of Medicine of the Pontificia Universidad Católica de Chile for their administrative support. Special thanks to the independent data safety monitoring committee (members in the Supplementary Appendix (SA)) for their oversight and to the participants enrolled in the study for their participation and commitment to this trial. Members of the CoronaVac03CL Study Team are listed in the SA.

Funding Information:
Funding: This research was funded by The Ministry of Health, Government of Chile, supported the funding of the CoronaVac03CL Study; The Confederation of Production and Commerce (CPC), Chile, supported the funding of the CoronaVac03CL Study; The Millennium Institute on Immunology and Immunotherapy, ANID-Millennium Science Initiative Program ICN09_016 (former P09/016-F) supports SMB, KA, PAG, and AMK; The Innovation Fund for Competitiveness FIC-R 2017 (BIP Code: 30488811-0) supports SMB, PAG, and AMK. SINOVAC contributed to this study with the investigational vaccine and placebo, and experimental reagents.

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.


  • COVID-19
  • CoronaVac®
  • SARS-CoV-2
  • immunization schedules
  • phase III clinical trial
  • vaccines


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