Formulation Approaches for COVID-19 Vaccines

COVID-19 is a respiratory disease caused by a new type of coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In 2019, this disease was discovered in Wuhan, China, and since then it has pandemically infected and, unfortunately, in many cases taken the lives of millions of people globally. Since the emergence of COVID-19, the entire biopharmaceutical research community has focused on the swift development of vaccines that can hinder the spread of the virus and reduce the shockingly high number of deaths. These efforts have led to the approval of a new class of vaccines known as messenger RNA (mRNA) vaccines, which were independently developed by Pfizer-BioNTech and Moderna. The mRNA vaccines are formulated as nanoparticles (NPs) where the fragile mRNA is encapsulated to stabilize the mRNA and enhance efficacy. Through accelerated approval of regulatory authorities, there are currently 10 approved vaccines, 153 candidate vaccines in clinical development, and 196 vaccines in preclinical development. The clinical candidates include seven NP-based vaccines, which are mainly based on protein subunits or RNA-based platforms. This chapter will provide insights into SARS-CoV-2 structure, potential vaccine approaches, the currently approved COVID-19 vaccines, and the candidates in preclinical and clinical development. The advancement in nanotechnology has enabled the utilization of various forms of NPs in vaccine development, such as liposomes, lipid NPs, protein NPs, and nanobodies. Therefore, this chapter will also detail the different types of potential NPs available for vaccine development and the formulation of these vaccines in terms of active ingredients, excipients, and storage.