Utilization of Viral Vector Vaccines in Preparing for Future Pandemics

MA, Tovar-Rosero YY, Oñate AA, O'Ryan M. Two centuries of vaccination: historical and conceptual approach and future perspectives

Over the past two centuries, vaccines have been critical for the prevention of infectious diseases and are considered milestones in the medical and public health history. The World Health Organization estimates that vaccination currently prevents approximately 3.5-5 million deaths annually, attributed to diseases such as diphtheria, tetanus, pertussis, influenza, and measles. Vaccination has been instrumental in eradicating important pathogens, including the smallpox virus and wild poliovirus types 2 and 3. This narrative review offers a detailed journey through the history and advancements in vaccinology, tailored for healthcare workers. It traces pivotal milestones, beginning with the variolation practices in the early 17th century, the development of the first smallpox vaccine, and the continuous evolution and innovation in vaccine development up to the present day. We also briefly review immunological principles underlying vaccination, as well as the main vaccine types, with a special mention of the recently introduced mRNA vaccine technology. Additionally, we discuss the broad benefits of vaccines, including their role in reducing morbidity and mortality, and in fostering socioeconomic development in communities. Finally, we address the issue of vaccine hesitancy and discuss effective strategies to promote vaccine acceptance. Research, collaboration, and the widespread acceptance and use of vaccines are imperative for the continued success of vaccination programs in controlling and ultimately eradicating infectious diseases.

An Overview of SARS-CoV-2 Etiopathogenesis and Recent Developments in COVID-19 Vaccines

The Coronavirus disease-2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has significantly impacted the health and socioeconomic status of humans worldwide. Pulmonary infection of SARS-CoV-2 results in exorbitant viral replication and associated onset of inflammatory cytokine storm and disease pathology in various internal organs. However, the etiopathogenesis of SARS-CoV-2 infection is not fully understood. Currently, there are no targeted therapies available to cure COVID-19, and most patients are treated empirically with anti-inflammatory and/or anti-viral drugs, based on the disease symptoms. Although several types of vaccines are currently implemented to control COVID-19 and prevent viral dissemination, the emergence of new variants of SARS-CoV-2 that can evade the vaccine-induced protective immunity poses challenges to current vaccination strategies and highlights the necessity to develop better and improved vaccines. In this review, we summarize the etiopathogenesis of SARS-CoV-2 and elaborately discuss various types of vaccines and vaccination strategies, focusing on those vaccines that are currently in use worldwide to combat COVID-19 or in various stages of clinical development to use in humans.

Recent advances in respiratory immunization: A focus on COVID-19 vaccines

The development of vaccines has always been an essential task worldwide since vaccines are regarded as powerful weapons in protecting the global population. Although the vast majority of currently authorized human vaccinations are administered intramuscularly or subcutaneously, exploring novel routes of immunization has been a prominent area of study in recent years. This is particularly relevant in the face of pandemic diseases, such as COVID-19, where respiratory immunization offers distinct advantages, such as inducing systemic and mucosal responses to prevent viral infections in both the upper and lower respiratory tracts and also leading to higher patient compliance. However, the development of respiratory vaccines confronts challenges due to the physiological barriers of the respiratory tract, with most of these vaccines still in the research and development stage. In this review, we detail the structure of the respiratory tract and the mechanisms of mucosal immunity, as well as the obstacles to respiratory vaccination. We also examine the considerations necessary in constructing a COVID-19 respiratory vaccine, including the dosage form of the vaccines, potential excipients and mucosal adjuvants, and delivery systems and devices for respiratory vaccines. Finally, we present a comprehensive overview of the COVID-19 respiratory vaccines currently under clinical investigation. We hope this review can provide valuable insights and inspiration for the future development of respiratory vaccinations.