This study states that the COVID-19 was declared a global pandemic by the WHO in March 2020.1 Toward the end of November 2020, the pandemic had spread to 215 countries and territories, infecting over 61 102 236 people, causing 1 433 132 deaths2 and had an unprecedented negative impact on economic activity, education, travel, food production, and social activities.3-6 Despite a global effort to evaluate treatments for COVID-19, no anti-viral agents have yet been identified as effective treatment.7, 8 Development of an effective vaccine to provide immunization was therefore identified early on as the main exit strategy from this global pandemic. As a result, multiple vaccine development programs across the world have been working to develop an effective vaccine for COVID-19, and as of the end of November 2020, at least 55 vaccines were undergoing clinical trials on humans with at least 3 seeking approval for public use.
Vaccination requires inoculating a certain proportion of the at-risk population in order to achieve immunity of the whole population.
Reference link- https://onlinelibrary.wiley.com/doi/10.1111/irv.12847
