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Review
. 2021 Jan 11;9(1):39.
doi: 10.3390/vaccines9010039.

A COVID-19 Vaccine: Big Strides Come with Big Challenges

Juanita Mellet  1 , Michael S Pepper  1
Affiliations
Review

A COVID-19 Vaccine: Big Strides Come with Big Challenges

Juanita Mellet et al. Vaccines (Basel). .

Abstract

As of 8 January 2021, there were 86,749,940 confirmed coronavirus disease 2019 (COVID-19) cases and 1,890,342 COVID-19-related deaths worldwide, as reported by the World Health Organization (WHO). In order to address the COVID-19 pandemic by limiting transmission, an intense global effort is underway to develop a vaccine against SARS-CoV-2. The development of a safe and effective vaccine usually requires several years of pre-clinical and clinical stages of evaluation and requires strict regulatory approvals before it can be manufactured in bulk and distributed. Since the global impact of COVID-19 is unprecedented in the modern era, the development and testing of a new vaccine are being expedited. Given the high-level of attrition during vaccine development, simultaneous testing of multiple candidates increases the probability of finding one that is effective. Over 200 vaccines are currently in development, with over 60 candidate vaccines being tested in clinical trials. These make use of various platforms and are at different stages of development. This review discusses the different phases of vaccine development and the various platforms in use for candidate COVID-19 vaccines, including their progress to date. The potential challenges once a vaccine becomes available are also addressed.

Keywords: COVID-19; SARS-CoV-2; immune response; vaccine; vaccine development; vaccine platforms.

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Conflict of interest statement

The authors have no conflict of interest to declare.

Figures

Figure 1
Figure 1
SARS-CoV-2 vaccine types. SARS-CoV-2 vaccines currently in pre-clinical and clinical evaluation make use of various platforms (image created by Juanita Mellet).
Figure 2
Figure 2
Platforms in use for COVID-19 candidate vaccine development in pre-clinical (blue) and clinical (green) trials [9]. APC: antigen presenting cell; DNA: deoxyribonucleic acid; RNA: ribonucleic acid. (Data figure created by Juanita Mellet.)
Figure 3
Figure 3
Phases of vaccine development (image created by Juanita Mellet).
Figure 4
Figure 4
COVID-19 candidate vaccines. (a) The number of candidate COVID-19 vaccines in pre-clinical and clinical evaluation [9]. (b) The number of candidate COVID-19 vaccines in different phases of clinical evaluation [9]. (Data figures created by Juanita Mellet.)
See this image and copyright information in PMC

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