An Overview of the Pathogenesis, Transmission, Diagnosis, and Management of Endemic Human Coronaviruses: A Reflection on the Past and Present Episodes and Possible Future Outbreaks

Abstract

The outbreak of the 2019 coronavirus pandemic caught the world by surprise in late 2019 and has held it hostage for months with an increasing number of infections and deaths. Although coronavirus was first discovered in the 1960s and was known to cause respiratory infection in humans, no information was available about the epidemic pattern of the virus until the past two decades. This review addresses the pathogenesis, transmission dynamics, diagnosis, management strategies, the pattern of the past and present events, and the possibility of future outbreaks of the endemic human coronaviruses. Several studies have described bats as presumptive natural reservoirs of coronaviruses. In essence, the identification of a diverse group of similar SARS coronaviruses in bats suggests the possibility of a future epidemic due to severe acute respiratory syndrome (SARS-like) coronaviruses originating from different reservoir hosts. The study also identified a lack of vaccines to prevent human coronavirus infections in humans in the past, however, the recent breakthrough in vaccine discovery and approval for emergency use for the treatment of Severe Acute Respiratory Syndrome Coronavirus 2 is commendable. The high rates of genomic substitution and recombination due to errors in RNA replication and the potential for independent species crossing suggest the chances of an entirely new strain evolving. Therefore, rapid research efforts should be deployed for vaccination to combat the COVID-19 pandemic and prevent a possible future outbreak. More sensitization and enlightenment on the need to adopt good personal hygiene practices, social distancing, and scientific evaluation of existing medications with promising antiviral effects against SARS-CoV-2 is required. In addition, intensive investigations to unravel and validate the possible reservoirs, the intermediate host, as well as insight into the ability of the virus to break the species barrier are needed to prevent future viral spillover and possible outbreaks.

Keywords: MERS-CoV; SARS-CoV; SARS-CoV-2; aerosols; coronaviruses; globalization; pandemic; vaccine; vulnerable individuals.

Figure 1

(a). The general structural representation of human coronaviruses. (b) Molecular structural description of SARS-CoV-2 [7] Key: RNP (ribonucleocapside), RBD (receptor binding domain).

Figure 1

(a). The general structural representation of human coronaviruses. (b) Molecular structural description of SARS-CoV-2 [7] Key: RNP (ribonucleocapside), RBD (receptor binding domain).