I thought a brief overview of the coronaviruses strains would be helpful.

Coronavirus: Any of a family (Coronaviridae) of single-stranded RNA viruses that have a lipid envelope studded with club-shaped projections, infect birds and many mammals including humans, and include the causative agents of MERS, SARS, and COVID-19.

There are more than 200 types of coronaviruses. Most are only contagious to animals.

There are seven types of coronaviruses that are contagious to humans.

Four types (NL63, 229E, OC43, and HKU1) are responsible for 15 to 30% of the world’s common cold cases every year and are considered endemic.

Two other types are considered epidemic: Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). The SARS outbreak, which affected 26 countries, first infected humans in the Guangdong province of southern China in 2002, and MERS, which was first reported in 2012, is prevalent in the Middle East.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the scientific name of the virus that causes the disease COVID-19. For simplicity, I use COVID-19 interchangeably when referring to the disease or the virus. This virus originated in Wuhan, China in 2019 and is currently a pandemic.  People are usually referring to COVID-19 when they say coronavirus, but technically that is the virus family, not the virus itself.

The main difference lies in the severity of the illnesses they cause. The first four respiratory viruses range from mild to medium, while SARS and MERS can cause respiratory illness of high severity. The data obtained so far shows that COVID-19 has by far the widest range of severity, ranging from mild to severe.

The exact COVID-19 mortality rate is unknown at this time. The mortality rate of any pandemic is likely to be overestimated at the start of an outbreak because a lot of mild cases are missed. With COVID-19, studies are showing almost half of all infected people can be asymptomatic – meaning the virus is not always detected and therefore not recorded.

Estimates show the COVID-19 mortality rate as slightly to moderately more fatal than most flu strains.The mortality rate for influenza is estimated around 0.1%. It is commonly cited than in an average year, influenza kills 500,000 people worldwide. Compared to the four respiratory coronaviruses, the mortality rate for COVID-19 is much higher. Although compared to SARS (9.6%) and MERS (34.4%), COVID-19 shows a lower mortality rate with a wider spread (higher R0), making the total number of deaths greater. The image below shows COVID-19 at 2%, which is higher than most current projections.