| Current Status of COVID-19 Vaccine |
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Dr Gilbert T CHUA MBBS, PDipID, MRCPCH(UK), FHKCPaed, FHKAM(Paed)
Prof Yu-lung LAU MBChB, MD (Hon), FRCPCH, FHKAM, FHKCPaed
INTRODUCTION The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first emerged in Wuhan, China in December 2019, rapidly spreading to 216 countries and territories and declared a pandemic by the World Health Organization (WHO) on March 11, 2020, with more than 60 million confirmed cases and 1.4 million deaths worldwide by the end of November 2020.1 This SARS-CoV-2 is a perfect pandemic virus with higher reproduction number and case fatality rate than seasonal influenza virus, hence cannot be just treated as a “simple flu”. Moreover, the incubation period is longer with infectivity begins days before symptoms onset and many cases are asymptomatic yet infectious resulting in difficulties in interrupting transmission. There is currently no effective treatment, with only non-pharmacological strategies to control the spread of SARS-CoV-2 virus. However, measures such as social distancing, border restrictions, quarantine and isolation carry an enormous negative impact on health, economic, environmental and social changes.2 The current hope to restore global norms is the development of an effective pandemic vaccine, compressing the usual development timeline from 10 – 15 years to 1 – 2 years by bypassing the conventional stepwise approach of vaccine development. Such compression of the timeline demands the development of multiple vaccine platforms and strategies simultaneously because there is so much uncertainty regarding vaccine efficacy and safety, demanding an approach as diverse as possible to increase the chance of success.
WHAT ARE THE CURRENT COVID-19 VACCINE CANDIDATES? In less than 12 months since the identification of the SARS-CoV-2 virus, 44 vaccine candidates were undergoing clinical evaluation, and over 154 vaccine candidates in pre-clinical evaluation.3 The speed of COVID-19 vaccine development is unprecedented, as compared to no suitable vaccine developed for MERS and SARS 6 years and 17 years after their first outbreaks, respectively. It usually takes more than a decade, and over USD 500 million investment in developing a vaccine, and up to 93% vaccine candidate tested in pre-clinical animal studies would not have been not able to be registered as a final product for clinical use.4 Multiple vaccine production platforms for these COVID-19 vaccines are being pursued, and we have chosen one each from some of these platforms which provide leading vaccine candidates being tested in phase III. Table 1 summarises the different types of production platforms that were being applied in the development of COVID-19 vaccines.
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