Abstract
The development of vaccines for COVID-19 occurred at an unprecedented pace, and 32 vaccines using a broad range of technologies had received authorization for use on an emergency basis by the end of 2021, from either a national regulatory authority or the World Health Organization. However, 27 of those 32 vaccines had little impact on the global course of the pandemic. Only five vaccines, from AstraZeneca, Pfizer/BioNTech, Sinovac, Moderna, and Sinopharm, were manufactured, authorized, and distributed in time to significantly impact the number of deaths worldwide. Together, these five vaccines averted an estimated 17 million deaths in the first year of the vaccination campaign. The shared characteristic of these five manufacturers was their ability to rapidly develop and scale up vaccine production to deliver the large manufacturing volumes required to immunize large segments of the global population. Because the development and manufacturing of these vaccines was generally on the critical path to authorization and supply, the technical activities involved with development, scale-up, testing, technology transfer, and full-scale manufacturing, as well as aspects of the Chemistry, Manufacturing, and Controls (CMC) regulatory interactions, are examined for each vaccine and technology for which information is available in the public domain to provide lessons learned and recommendations on proactive actions to better prepare us for a future pandemic response. The critical success factors include prior experience with commercialization and approval, robust quality systems, rigorous process development strategies, flexible manufacturing facilities with a skilled workforce, collaboration, access to consumables, reagents, and adjuvants (if relevant), and an equitable distribution of the global vaccine manufacturing network.