The length of the genome (RNA) is by far the longest compared to other viruses: it is approximately 30000 nucleotides long and, in terms of size, also remains one of the largest in relation to the size of the vinion, which reaches 80-180 mm in diameter [1].

The first studies on corona viruses

The first human coronaviruses were isolated from the trachea of a child in whom cold symptoms were observed. This was coronavirus B814, whose exact species affiliation was not fully understood due to the sample being lost before the advent of specialised testing methods.

How coronavirus infection occurs was described on the basis of studies conducted with healthy humans: a study group was infected with coronavirus 229E and OC43. The symptoms that appeared in healthy people were mainly the typical symptoms of a cold: rhinitis, swelling of the nasal mucosa, sometimes also coughing. The length of time the symptoms persisted oscillated around one week, after which they spontaneously disappeared. Repeated clinical experience confirmed the low capacity of coronaviruses to cause severe symptoms. Coronaviruses can pose a threat to people with weakened immunity, e.g. children, the elderly or individually, depending on a person's weakened immune system, by causing an illness whose course can be very severe. These include bronchitis,subglottic laryngitis and pneumonia. It was also theorised that coronaviruses were capable of generating other diseases, such as those related to the digestive system, but this thesis could not be confirmed, and the presence of coronavirus in the faeces was itself the result of its expansion rather than active infection.