Covid-19: Warp Speed Vaccines

A vaccine is required to effectively control the COVID-19 pandemic in the mid and long term. The development of vaccines against SARS-CoV-2 was initiated as soon as the genetic sequence of the virus was published, and has evolved at an unprecedented speed, with a first clinical trial launched in March 2020. One year later, more than a dozen of vaccines based on different concepts, with some having been evaluated only in clinical trials so far, are authorized under emergency procedures. Here, we review these vaccines, compare their properties and discuss the challenges they face, including the emergence of viral variants of concern.