Lung abscess and gangrene are complications of viral-bacterial pneumonia. COVID-19 infection can be an initiating factor for its occurrence or to be a background. The aim of our study was to analyze the impact of COVID-19 infection on the development and results of surgical treatment of severe lung infections. METHODS:We compared two groups of patients operated on for lung abscess or gangrene and complications. The 1 st group consisted of patients treated in period from March 2019 to March 2020 (during the year preceding the beginning of COVID-19 in our region). The 2 nd group consisted of patients treated in the period from April 2020 to April 2021 (during an equivalent period of time during COVID-19 in our region). The data of the period from 2015 to 2018 were also used for a comparative assessment. RESULTS:The 1 st group consisted of 19 (86%) males and 3 (14%) females, aged 30 to 68 (Me [LQ; UQ] -56 [40; 61]) years, with acute lung abscess (11 cases, 50%) or gangrene (11 cases, 50%). 2 (33%) patients with lung abscess and 5 (45%) patients with lung gangrene died. The overall mortality rate was 32%. The 2 nd group consisted of 28 (84%) males and 5 (16%) females, aged from 24 to 83 (49 [40; 57]) years, with acute lung abscess (16 cases, 48%) or gangrene (17 cases, 52%). COVID-19 was diagnosed at the onset of the disease in 15 (45%) cases (4 had an active process at the time of surgery). 4 (12%) patients got an illness staying in the department. 3 (40%) patients with lung abscess and 3 (18%) patients with lung gangrene died. The overall mortality rate was 18%. 1 in 14 patients without COVID-19 died. 5 of 19 patients with COVID-19 have died. COVID-19 was diagnosed at the onset of the disease and was active at the time of surgical treatment in 2 died patients. 3 died patients got an illness with COVID-19 staying in the department, while 1 patient got an illness during the period of preparation for discharge after successful treatment of a lung abscess. Mortality did not differ between patients with and without COVID-19 (p Fisher ¼0.21). The overall mortality rate was 18%. Patients of the 1 st and 2 nd groups did not differ in age (U ¼ 295.0; p Mann-Whitney ¼ 0.25), gender (p Fisher ¼ 1.0), frequency of lung abscess and gangrene (p ¼ 0.95), abscess mortality (p Fisher ¼ 1.0) and gangrene mortality (p Fisher ¼ 0.20), overall mortality (c 2 Yates ¼ 0.71; p ¼ 0.40).There were 60 patients operated on for acute lung abscess or gangrene in 2015, 43in 2016, 39in 2017, 32in 2018. The incidence of lung abscess and gangrene requiring surgical treatment was 50% higher during the spread of COVID-19 than in the previous year, but did not exceed the number of observations in the period 2015-2018.CONCLUSIONS: Overall, COVID-19 did not significantly affect the incidence and outcome of surgical treatment of severe lung infections. But active COVID-19 infection aggravates the individual prognosis and the outcome.CLINICAL IMPLICATIONS: Information can be used in the surgery of severe lung infections.DISCLOSURES: no disclosure on file ...