nSARS-CoV-2 and COVID-19 Pandemic: From Emergence to Vaccination

Since its first emergence in Wuhan, China, the novel severe acute respiratory syndrome coronavirus-2 (nSARS-CoV-2)-associated coronavirus disease 2019 (COVID-19) has alarmingly disrupted the world’s healthcare systems and evolved as a major public health threat around the globe. Despite the advent and emergency use listing (EUL) of mRNA- and adenovirus-based vaccines to prevent the further transmission of SARS-CoV-2 infection, the pandemic burden is still significant worldwide as new cases are being reported daily. It is the first time in vaccine history that vaccines against SARS-CoV-2 have been rapidly designed, developed, and clinically evaluated and surprisingly, they have worked better than clinical trial data predicted. However, this EUL of vaccines prior to full approvals stems from the perception of inadequate testing and experience with benefit–risk balance. Similarly, the emergence of superspreader SARS-CoV-2 mutant virus strains at the end of 2020 has also raised concerns about the efficacies of approved vaccines in real-world clinical scenarios. The inconclusive, murky, and anecdotal reports about vaccine hesitancy, antibody-dependent enhancement of disease risk in vaccine injectors, and certain severe adverse events have also frightened a large segment of the world’s population, preventing them from receiving the vaccine. This review presents an overview of the remarkable efforts rendered by different vaccine producers to combat the pandemic, explains the challenges of vaccine safety and efficacies against SARS-CoV-2 variants of concern, and explores their potential roles in eradicating the COVID-19 pandemic.