Chattanooga Times Free Press
March 18, 2020
Coronaviruses are a family of viruses, some of which cause respiratory illness in humans. The virus exhibits a crown-like halo, when viewed under an electron microscope, which is how it got its name.
Coronaviruses have been found circulating among animals, such as camels, cats and bats and a few have jumped to people — a spread that is defined by epidemiologists as “zoonotic.”
Prior to December 2019, there were four coronaviruses that were known to be circulating among people, two of which were discovered in the 1960’s and two more discovered in the past 2 decades. These coronaviruses caused about 25% of colds.
Two other coronaviruses have emerged over the past two decades that have caused severe illness and death. One caused Severe Acute Respiratory Syndrome (SARS), a disease that emerged in 2002, that infected about 8,000 and killed about 800. The mortality rate for this virus was about 11%.
Another coronavirus causes Middle East Respiratory Syndrome (MERS). The virus emerged in Saudia Arabia in 2012 and has sickened about 2,500 and killed about 860. The mortality rate for MERS has been estimated at about 29%.
The viruses that cause SARS and MERS aren’t easily transmissible between people, and public health officials have been able to control their spread. There has been no community spread of SARS since 2003, according to the World Health Organization. SARS is thought to have originated in bats, then jumped to civet cats, and then to humans. MERS is believed to have passed from camels to humans.
In December, another coronavirus emerged that shared some of the same genes as SARS, and therefore has been named SARS-CoV-2019, by the WHO. The understanding of this virus, which causes the disease COVID-19, is evolving almost daily, as scientists have raced to understand how contagious it is, its incubation period, it’s morbidity and mortality rate, and how it passes between people.
The most recent WHO report suggested that the average mortality rate for COVID-19 is 3.4%, but this number continues to evolve.
On Jan. 30, the World Health Organization declared 2019-nCoV, a coronavirus, a public health emergency of international concern and on March 10, declared it a pandemic. The last time it declared a pandemic was the swine flu in 2009.