Recent Update of COVID-19 Vaccines.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has been recently identified as a novel member of beta coronaviruses (CoVs) and the cause of coronavirus disease 2019 (COVID-19). It has been first discovered in China and soon has spread across continents with an escalating number of mortalities. There is an urgent need for developing a COVID-19 vaccine to control the rapid transmission and the deleterious impact of the virus. The potent vaccine should have a good tolerable and efficacious profile to induce target-specific humoral and cellular immune responses. It should also exhibit no or minimal detrimental effects in children, young adults, and elderly people with or without co-morbidities from different racial backgrounds. Previously published findings of SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV) played vital role in the characterization of surface spike proteins as the tool of entry of the SARS-CoV-2 into host cells. It has become evident that SARS-CoVs have high genetic similarity and this implies antecedent vaccination strategies could be implicated in the production of COVID-19 vaccines. Although several vaccines have been approved and rolled out, only a handful of them have passed the three phases of clinical studies. This review highlights the completed, and ongoing clinical trials of COVID-19 vaccines and efforts are being made globally to avert the pandemic.