Coronavirus disease 2019 (COVID-19) has developed as a pandemic, and it created an outrageous effect on the current healthcare and economic system throughout the globe. To date, there is no appropriate therapeutics or vaccines against the disease. The entire human race is eagerly waiting for the development of new therapeutics or vaccines against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Efforts are being taken to develop vaccines at a rapid rate for fighting against the ongoing pandemic situation. Amongst the various vaccines under consideration, some are either in the preclinical stage or in the clinical stages of development (phase-I, -II, and -III). Even, phase-III trials are being conducted for some repurposed vaccines like Bacillus Calmette–Guérin, polio vaccine, and measlesmumps-rubella. We have highlighted the ongoing clinical trial landscape of the COVID-19 as well as repurposed vaccines. An insight into the current status of the available antigenic epitopes for SARS-CoV-2 and different types of vaccine platforms of COVID-19 vaccines has been discussed. These vaccines are highlighted throughout the world by different news agencies. Moreover, ongoing clinical trials for repurposed vaccines for COVID-19 and critical factors associated with the development of COVID-19 vaccines have also been described.

Ebola virus disease (EVD) is associated with haemorrhagic fever in humans and nonhuman primates, with a high rate of fatality (up to 90%). Some outbreaks in human history have proven the lethality of EVD. The recent epidemic of 2014 and 2015 in West Africa was the deadliest of all time (11 284 deaths). To understand the transmission dynamics, we have reviewed the epidemiology of EVD to date. The absence of any licensed vaccines or approved drugs against Ebola virus (EBOV) further highlights the severity and crisis level of EVD. Some organizations (public and private) are making considerable efforts to develop novel therapeutic approaches or vaccines to contain the outbreak of EBOV shortly. Here, we summarized the various potential drugs and vaccines (undergoing multiple phases of clinical trials) that have arisen as an alternative against EBOV, and we highlighted the numerous issues and limitations hindering this process. Alternatively, an increasing focus on strengthening the medical and civic health structure could provide speedy benefits in containing the spread of EVD, as well as offer a resilient foundation for the deployment of novel drugs and vaccines to the affected countries, once such drugs and vaccines become available.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus (CoV), has recently emerged as a significant pathogen for humans and the cause for the recent outbreak of the 2019 novel coronavirus disease (COVID-19) throughout the globe. For developing any preventive measure, an understanding of the zoonotic pattern for this virus is a necessity. We should have a clear knowledge of its reservoir host, its distribution pattern and spreading routes. Information about zoonotic reservoirs and its transmission among them can help to understand the COVID-19 outbreaks. In this article, we discuss about the bats as the zoonotic reservoir of several CoV strains, co-existence of bats and CoV/viruses, the sequence similarity of SARS-CoV-2 with bat SARS-like CoV, the probable source of the origin of SARS-CoV-2 strain and COVID-19 outbreak, intermediate host of CoVs and SARS-CoV-2, human to human transmission and the possibility to maintain the zoonotic barriers. Our knowledge about the zoonotic reservoir of SARS-CoV-2 and its transmission ability may help develop the preventive measures and control for the future outbreak of CoV.