In the mid-1960s, the scientific community was searching for viruses responsible for the common cold. By that time, techniques already existed to isolate some viruses responsible for colds, such as rhinoviruses and adenoviruses, but research had left many strains undetected: 35% of people with colds had viruses that scientists could not identify.
Several names are involved in the discovery of the first human coronaviruses: Dorothy Hamre, John Procknow, June Almeida and David Tyrrell.
In 1965, University of Chicago researcher Dorothy Hamre discovered a new type of virus while studying tissue cultures from students with colds. It was called 229E. She didn't know it yet, but she was looking at the first known human coronavirus.
In England, Dr. David Tyrrell examined this virus under an electronic microscope, finding that it resembled another virus found in the 1930s from chickens with a type of bronchitis. Also involved in this research was another woman, Dr. June Almeida, of Scottish origin.
As early as 1965, almost at the same time as Hamre and Procknow's team, Tyrrel and Almeida discovered a new type of virus, which they called B814, in the nasal washes of a child with the common cold. But this virus could never be grown in the lab.
The two teams published their respective studies almost simultaneously, a few days apart, in January 1966; but Dorothy Hambre and John Procknow published it earlier. Today, both coronaviruses are considered to be of the same species (229E) and therefore Almeida and Tyrrel's coronavirus is not listed among the known human coronaviruses.
Almeida and Tyrrell's advances helped to understand that these new organisms were a new coronavirus, the first to be known to affect humans. Of them is the merit of obtaining the first photograph of a coronavirus under the microscope. Almeida did not sign the scientific article where it is described. Therefore, she is often credited with obtaining the first photograph under the microscope of a human coronavirus, and Dorothy Hamre with finding the first human coronavirus.
Shortly thereafter, Dr. McIntosh, a member of a team at Harvard Medical School, was also searching for the hidden causes of the common cold. His team discovered in 1967 what is now known as OC43, another common human coronavirus that still causes respiratory infections today.
In 1968 the term 'coronavirus' was coined, based on the appearance under an electron microscope of its crown-like surface, but not the crown of kings, but the crown understood as the outer layer of the Sun.
21st century: five types of human coronavirus discovered
It was not until the 21st century that the remaining coronaviruses that we know can affect humans were discovered. So far, seven coronaviruses are known to be capable of affecting humans: 229E, OC43, NL63, HKU1, SARS-CoV, MERS, SARS-CoV-2.
In November 2002, in the Chinese province of Canton, the coronavirus SARS was detected. SARS causes severe acute respiratory syndrome, with somewhat more severe symptoms than the previously discovered coronaviruses: they included difficulty in breathing, lack of oxygen in the blood and pneumonia. This condition caused an epidemic outbreak of considerable proportions, affecting 8,000 people and killing 800.
Shortly thereafter, two much milder coronaviruses were discovered. The human coronavirus NL63 (HCoV-NL63) was discovered in January 2003 in a child with bronchiolitis in the Netherlands. HKU1 (HCoV-HKU1) was first detected in two patients in Hong Kong in 2005. Both coronaviruses caused respiratory syndromes with relatively mild symptoms: fever, dry cough and severe headache. Both coronaviruses, along with other types of viruses, are believed to be responsible for common colds.
In 2012, another new type of coronavirus, MERS-CoV, was detected in Saudi Arabia, causing Middle East Respiratory Syndrome. It also causes a serious respiratory condition and has a high mortality rate of up to 35%.
The last known human coronavirus is SARS-CoV-2, which is very similar to SARS, which causes VICD-19 disease, and was first reported in December 2019 in the Chinese city of Wuhan. The latter, like SARS and MERS, also caused an outbreak of considerable proportions, which eventually reached pandemic status; but it is less lethal than these, although with a much higher rate of contagion.