COVID-19 vaccines: Update of the vaccines in use and under development

The ongoing COVID-19 pandemic has imposed a series of challenges on the scientific community. One of the biggest was the development of safe and effective vaccines in record time, which could be achieved through a global effort. A topic of great discussion has been the technology surrounding these vaccines: ranging from the well-known inactivated virus vaccines to the latest RNA vaccines. As vaccines became available, another point also came into question: their efficacy and effectiveness against the original Wuhan strain and its variants. Among the numerous variants, 5 of them (Alpha, Beta, Gamma, Delta and, more recently, Omicron) gained greater prominence due to their epidemiological relevance. In this scenario, with numerous variants and several vaccine options, scientific information can often be mismatched. This review aims to provide an overview of the efficacy, effectiveness, and safety of 11 vaccines in use or under development against the original Wuhan strain and the variants of concern identified by the World Health Organisation (WHO). Simultaneously, we aim to explore possible scenarios that can be expected shortly regarding new variants and vaccines. Overall, COVID-19 vaccines have satisfactory efficacy and loss of effectiveness against SARS-CoV-2 variants, especially the Omicron strain.