The SARS-CoV-2 has changed since it began to spread. The major mutations identified by the WHO and prevalent in many patients globally are ancestral, beta, delta, and omicron. Clinical characteristics and mortality have reportedly changed over the duration of each mutation. We assessed clinical characteristics and outcomes of ICU patients with a positive SARS-CoV-2 test result during the waves of COVID-19.

Patients and methods

Turkiye has experienced 4 COVID-19 waves as seen in Fig. 1. The waves were determined by projection according to the number of cases announced by the Ministry of Health on a daily basis (wave 1: November 2020–January 2021; wave 2: February–May 2021; wave 3: July–November 2021; wave 4: December 2021–March 2022). All patients admitted to COVID ICU were included. Patient characteristics, type of oxygen supply and mechanical ventilation, length of stay and mortality rates were evaluated.

Results

A total of 509 patients during the four waves of COVID-19 were included. The patients admitted during individual waves were as follows; wave 1: 61 (12%), wave 2: 148 (29%), wave 3: 187 (37%), wave 4: 113 (22%). Characteristics of patients admitted were presented in Table 1. Overall median age was 70 (IQR:21), Median age was lowest during 2nd wave and highest during 4th wave (62 vs 76). Vaccination rate was quite low for overall population. Patients who did not received any dose of any kind of vaccine was 384 (75%). Overall ICU mortality was 81%. Mortality was lowest during 1st wave and highest during 4th wave (66% vs 86%) Outcomes of patients were presented in Table 2. Median length of stay was similar between waves.

Conclusion

In patients admitted to ICU with COVID-19 a varied pattern of traits and outcomes was seen between the waves. To ascertain whether the omicron is potentially less pathogenic than earlier versions more investigation is required.