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. And, the first description of human coronavirus published in the BMJ was during 1965.

They are the 2nd leading cause of the common cold, after rhinoviruses, and until recent decades, they rarely caused any disease more serious than a common cold in humans. People around the world commonly get infected with human coronaviruses 229E, NL63, OC43, and HKU1 say the CDC.

The first coronavirus was isolated in 1937. Some 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.

University of Glasgow researchers reported on April 13, 2020, that bats and rodents are considered high-risk sources for diseases that can hop over to humans. They compared 415 DNA and RNA viruses from animals that have spread to people. This statistical analysis estimated rodents were the most species-rich order of mammals and they also had the largest number of viruses that had moved to people.

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.

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. In humans, beta coronaviruses (SARS, and MERS) are associated with respiratory disease, 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. What is yet unclear is which animal is the intermediate species between bats and humans. For SARS it was civet cats, for MERS it is camels.

SARS-CoV-2 Prevention

The CDC published the 'Initial Public Health Response and Interim Clinical Guidance for the 2019 Novel Coronavirus Outbreak, United States, December 31, 2019–February 4, 2020.' Additionally, the CDC's Interim Guidance is available and will be updated as more information becomes available.

On February 3, 2020, the CDC published -Infection Prevention and Control Recommendations for Patients with Confirmed 2019 Novel Coronavirus (2019-nCoV) or Patients Under Investigation for 2019-nCoV in Healthcare Settings. Infection control procedures including administrative rules and engineering controls, environmental hygiene, correct work practices, and appropriate use of personal protective equipment (PPE) are all necessary to prevent infections from spreading during healthcare delivery.

Prompt detection and effective triage and isolation of potentially infectious patients are essential to prevent unnecessary exposures among patients, healthcare personnel, and visitors at the facility. All healthcare facilities must ensure that their personnel is correctly trained and capable of implementing infection control procedures; individual healthcare personnel should ensure they understand and can adhere to infection control requirements.

This guidance is based on the currently limited information available about COVID-19 related to disease severity, transmission efficiency, and shedding duration.

Relevant SARS-CoV-2 Links

Note: This content is sourced from the US CDC, and reviewed by health professionals, such as Dr. Robert Carlson, on April 21, 2020.