The largest number of definitive cases of COVID-19 detected in continental Europe belonged to Russia, England, and France, respectively. The results of a study by Zemtsov and Baburin, which examined the risk factors for mortality and morbidity from COVID-19 in Russia, showed that the increase in definitive diagnosis of COVID-19 in Russia was due to the addition of private laboratories to diagnose the disease and the use of public transportation system, such as buses and city trains. These vehicles had poor ventilation, which was effective in transmitting the disease from healthy carriers to others. Other important factors involved in the transmission of the disease were seasonal workers moving from the northern regions to industrial and densely-populated cities. The return of these workers, who were mostly young and possibly healthy and asymptomatic carriers, transmitted the disease from them to family members and relatives, especially the elderly and the chronically ill, and the disease was more severe and fatal in these people (
11).
According to a study by Brandily et al., the spread of the disease was different in various regions and cities of France. Poor economic conditions and poor environmental conditions, including living in slums, played a major role in the disease transmission and mortality from COVID-19 (
12). The results of a study by Pollán et al. in Spain showed that the central regions of the country were at high risk for COVID-19, and that social gatherings in these areas were effective in transmitting the disease (
13).
The highest case fatality rates of COVID-19 occurred in Bulgaria, Bosnia, and Greece, respectively. In a study by Sudharsanan et al., comparing the fatality of COVID-19 in ten countries, the highest case fatality rate was reported in Italy and the lowest in South Korea, which was almost inconsistent with the results of this study (
14). However, the high case fatality rate in some countries may be due to the lack of definitive diagnosis of COVID-19. Adherence to health protocols, such as the use of masks and social distancing, is still the only way to prevent the disease transmission.