COVID-19 vaccine: A recent update in pipeline vaccines, their design and development strategies

Abstract

Coronavirus Disease 2019 named as COVID-19 imposing a huge burden on public health as well as global economies, is caused by a new strain of betacoronavirus named as SARS-CoV-2. The high transmission rate of the virus has resulted in current havoc which highlights the need for a fast and effective approach either to prevent or treat the deadly infection. Development of vaccines can be the most prominent approach to prevent the virus to cause COVID-19 and hence will play a vital role in controlling the spread of the virus and reducing mortality. The virus uses its spike proteins for entering into the host by interacting with a specific receptor called angiotensin converting enzyme-2 (ACE2) present on the surface of alveolar cells in the lungs. Researchers all over the world are targeting the spike protein for the development of potential vaccines. Here, we discuss the immunopathological basis of vaccine designing that can be approached for vaccine development against SARS-CoV-2 infection and different platforms that are being used for vaccine development. We believe this review will increase our understanding of the vaccine designing against SARS-CoV-2 and subsequently contribute to the control of SARS-CoV-2 infections. Also, it gives an insight into the current status of vaccine development and associated outcomes reported at different phases of trial.

Keywords: COVID-19; Platforms; SARS-CoV-2; Targets; Vaccine designing.

Graphical abstract

Fig. 1a

Schematic diagram of genomic organization or open-reading frames (ORFs) of SARS-CoV, MERS-CoV and SARS-CoV-2. Variations in accessory proteins (yellow) in all the three strains of betacoronvirus organized within structural proteins, Spike (light blue, S), envelope (green, E), membrane (dark blue, M), nucleocapsid (purple, N) and non-structural proteins expressed in ORF 1a (brown) and ORF 1b (peach) are indicated. Untranslated regions at the N and C-terminals are represented respectively as 5′-UTR and 3′-UTR; kb indicates kilo base pairs. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 1b

Schematic structure of SARS-CoV-2 with its key structural proteins as target antigens for various vaccines production platforms. S protein is the major target antigen for most of the platforms except the conventional ones (Live attenuated and Inactivated vaccines) where the whole virion or the subunit of it is used to develop vaccines.

Fig. 2

Schematized representation of immunopathogenesis of SARS-CoV-2. SARS-CoV-2 acting on ACE-2 receptor (A) giving rise to the cascade of pathological mechanisms including, Activating innate line of defense (1) and subsequently giving rise to Humoral response (2), leading to Antibody dependent enhancement (ADE), T cell depletion, Lymphatic organs damage and Cytokine storm.