SARS-CoV-2 Vaccines: Where Are We Now?

Abstract

The best and safest way to control the coronavirus disease 2019 (COVID-19) pandemic is by using vaccination to generate widespread immunity. The urgent need to develop safe and effective COVID-19 vaccines was met with unprecedented speed and action from the global community. There are now 289 vaccines in the development pipeline. More remarkably, there are 20 publicly available vaccines, and more than 3.3 billion doses of COVID-19 vaccines have been administered across 180 countries. This is just the beginning of our fight against the pandemic. Even at the current vaccination rate, it could take years to vaccinate the world's population; many high-income countries are focusing on their needs, whereas the poorer nations are waiting for vaccines. There is still much that we do not understand about immunity to this new disease, and we will have to contend with the emerging variants. In this commentary, we describe the current status of COVID-19 vaccine development and provide insights into how the development and approvals happened so quickly. We discuss the clinical trial data that led to rapid emergency use authorization and the many challenges of global rollout. We also comment on some of the key unanswered questions and future directions for COVID-19 vaccine development and deployment.

Keywords: COVID-19 vaccines; DNA; Efficacy; Platforms; RNA; Regulatory pathway; Vaccination program; Viral vector.

Figure 1

Illustration of the various COVID-19 vaccine platforms in development. A series of conventional and novel platform technologies are being used to develop COVID-19 vaccines. The conventional platforms include live-attenuated or inactivated whole virus, protein subunit, and virus-like particles. Novel approaches include nucleic acid vaccines (DNA or mRNA), viral and bacterial vector vaccines, and cell-based vaccines. COVID-19, Coronavirus disease 2019; CTL, cytotoxic T cell; DC, dendritic cell; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.