Serological evidence of coronavirus aetiology was found in 11 patients out of 218 persons examined (5%) in the period of 1986-1987, and in 23 cases out of 311 patients (7.4%) in the period of 1987-1988. Antibody titres with a minimum of four-time elevated values in paired sera using the ELISA method were considered conclusive. Coronaviruses 229E and OC43 were employed. During the first period, more persons were infected by coronavirus 229E, while in the second period, by coronavirus OC43. The disease was equally spread over all the months of the years. For example, in the 1987-1988 period, most infections occurred in February, when out of 60 examined patients, 9 were coronavirus positive (15%).
[Acute respiratory disease caused by coronaviruses].