SARS = Severe Acute Respiratory Syndrome
MERS = Middle East Respiratory Syndrome
COVID-19 = Coronavirus Disease 2019

All 3 are diseases caused by novel respiratory pathogens.

Coronaviruses (CoV) are a very diverse family of viruses and have been identified as human pathogens since the 1960’s. Coronaviruses infect humans and many other vertebrates . Illness in humans is mostly respiratory or gastrointestinal infections, however symptoms can range from the common cold to more severe lower respiratory infections such as pneumonia. They have a large host range, which includes humans. However, the greatest amount of coronavirus diversity is seen in bats.

A new type of coronavirus can emerge when an animal coronavirus develops the ability to transmit a disease to humans. When germs are transmitted from an animal to a human, it’s called zoonotic transmission.

Coronaviruses that make the jump to human hosts can cause serious illness. This can be due to a variety of factors, particularly humans’ lack of immunity to the new virus. Here are some examples of such coronaviruses:

  • SARS-CoV, the virus that caused SARS, which was first identified in 2003
  • MERS-CoV, the virus that caused Middle East respiratory syndrome (MERS), which was first identified in 2012
  • SARS-CoV-2, the virus that causes COVID-19, which was first identified in 2019 and is the name given to the 2019 novel coronavirus, we refer “falsely” to as Coronavirus

A comparison between the 3 diseases can be found here.

Source: ECDC, Healthline, NIAID