Antiviral Inactivated Vaccines: Looking to the Past to Face the Future—A Narrative Review

Throughout human history, contagious infectious diseases have significantly impacted societies, shaping the fate of great dynasties and challenging economic and political systems, social relations, and the overall well-being of the human species. The SARS-CoV-2 pandemic brought unprecedented challenges, emerging in the context of extreme globalization and rapid technological development. The speed of viral spread, the highest absolute mortality rate caused by a viral agent in the last 100 years, and the severe economic and social consequences imposed an urgent need for vaccine development on a previously unimaginable timescale. The proven safety and efficacy of inactivated vaccines enabled the development and large-scale application of the first immunizer against SARS-CoV-2 in less than a year after the World Health Organization (WHO) declared the pandemic. In this review, we discuss the importance of inactivated antiviral vaccines and their historical impact in containing highly harmful diseases affecting humanity. We also explore the cellular mechanisms by which inactivated vaccines may induce immunogenic responses against viral pathogens. In addition, we bring to light a discussion about a fast, cost-effective, potentially efficient technology for large-scale immunizer production: High hydrostatic pressure (HHP), a method long supported by decades of preclinical studies and which is especially effective in the context of enveloped viruses. Finally, we discuss the role of inactivated antiviral vaccines in the face of advances in biotechnology and, therefore, the emergence of vaccines that use genetic engineering in their production, such as RNA, DNA and viral vaccines, which have gained special prominence during the COVID-19 pandemic.