Coronavirus Overview

Human coronaviruses are everywhere and were identified decades ago. Human coronavirus was cultured in the 1960s from nasal cavities of people with the common cold, reports a recent study.

They are the 2nd leading cause of the common cold, after rhinoviruses. 

People around the world commonly get infected with human coronaviruses 229E, NL63, OC43, and HKU1 say the CDC.

Some coronaviruses cause illness in people and others circulate among other animals, including camels, cats, and bats. Since its discovery, related coronaviruses have been found to infect cattle, pigs, horses, turkeys, cats, dogs, rats, and mice.

There are four main sub-groupings of coronaviruses, known as alpha, beta, gamma, and delta. Both the Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS), are betacoronavirus and have their origins in bats.

Both MERS and SARS have been known to cause severe illness in humans.

On January 9, 2020, China's CDC reported a novel coronavirus as the causative agent of the new coronavirus outbreak, which is phylogenetically in the SARS-CoV clade. This novel coronavirus has been named ‘severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), while the human disease has been classified by the WHO as COVID-19 disease.

An international team of scientists published a non-peer-reviewed study on May 31, 2020, what it calls the most comprehensive analysis ever done of such viruses. These researchers examine partial genetic sequences of 781 coronaviruses found in bats in China, more than one-third of which have never been published.

Although this analysis cannot pinpoint the origin of SARS-CoV-2, the virus that causes COVID-19, it does single out one genus, Rhinolophus, also known as Chinese horseshoe bats, as crucial to the evolution of coronaviruses.

Duke University’s Feng Gao, who led another analysis about the evolution of SARS-CoV-2, said in Science Advances, this new study underscores that researchers have just sampled “the tip of the iceberg” of the coronaviruses circulating between bats, that could jump into humans and other species.

Coronavirus Persistence

An analysis of 22 studies reveals that human coronaviruses, such as SARS, MERS, or endemic human coronaviruses can persist on inanimate surfaces like metal, glass, or plastic for up to 9 days.

But, these coronaviruses can be efficiently inactivated by surface disinfection procedures with 62–71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite within 1 minute. Other biocidal agents such as 0.05–0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate are less effective. 

Coronavirus Transmission

Airborne transmission via droplets and aerosols enables some of these viruses to spread efficiently among humans, causing outbreaks that are difficult to control. Because viruses spread by small particle aerosol do not require close contact, the source of infection may not be evident.

Small particles (less than 10 microns in diameter) can remain airborne for long periods of time. These small particles can be inhaled by susceptible persons in the same room or are capable of more distant spread as they are carried in air currents.

Novel Coronavirus SARS-CoV-2

The current outbreak of novel coronavirus SARS-CoV-2 originated in China but has now spread internationally, impacting an increasing number of countries. Reported illnesses have ranged from mild to severe cases, some resulting in fatalities, according to previous studies.

On February 5, 2020, JAMA published a new study from genetic sequencing data, it appears that there was a single introduction into humans followed by the human-to-human virus spread. This novel virus shares 79.5% of the genetic sequence with SARS-CoV and has 96.2% homology to a bat coronavirus. 

In addition, SARS-CoV-2 shares the same cell entry receptor, ACE2, with SARS-CoV.

Relevant Coronavirus Links

Note: This content is sourced from the US CDC, and reviewed by health professionals, such as Dr. Robert Carlson.