The main purpose of the study is to predict the magnitude of the Covid-19 pandemic by using epidemiological wavelength models in Turkey and at international level. Therefore, rstly, the rst 36 days of wavelengths based on the number of daily coronavirus cases in Turkey were calculated. In addition, 114 countries were compared in terms of Covid-19 wavelengths considering the cumulative number of the pandemic cases occured at the end of the rst 36 days for evaluation on an equal plane. In the last part of the study, the wavelengths of 185 countries were examined comparatively based on the cumulative number of cases at the end of the time frame from the rst epidemic case until 2020-04-16 (including that date). According to the ndings of wavelength obtained in Turkey, it was observed that case wavelength on 2020-04-11, death and recovered case wavelength on 2020-04-16, and net wavelength on 2020-03-26 reached its peak. China was the country having the highest wavelength of case, death, and recovered case wavelengths in 114 countries at the end of the rst 36 days since the rst case occurred. In that country, wavelengths of case, death and recovered case were 33.6, 23.5 and 30.7, respectively. The rst three countries with the highest net wavelength at the end of the rst 36 days were Serbia (36.5), Netherlands (33.5) and Portugal (30.3), respectively. On the other hand, the country having the highest case and death wavelengths among 185 countries in the time interval from the rst case until the date of 2020-04-16 (including that date) was the USA, and case and death wavelengths were 39.7 and 30.7, respectively. The country with the highest recovered case wavelength was China (33.3). The rst 3 countries with the highest wavelengths are Canada (51.4), England (45.0) and Serbia (39.2), respectively.

The number of COVID-19 patients is dramatically increasing worldwide. Treatment in intensive care units (ICU) has become a major challenge; therefore, early recognition of severe forms is absolutely essential for timely triaging of patients. While the clinical status, in particular peripheral oxygen saturation (SpO2) levels, and concurrent comorbidities of COVID-19 patients largely determine the need for their admittance to ICUs, several laboratory parameters may facilitate the assessment of disease severity. Clinicians should consider low lymphocyte count as well as the serum levels of CRP, D-dimers, ferritin, cardiac troponin and IL-6, which may be used in risk stratification to predict severe and fatal COVID-19 in hospitalised patients. It is more likely that the course of the disease will be unfavourable if some or all of these parameters are altered.