In patients (n=31) who died from severe COVID-19 in the acute (average duration of illness 17.31 days, age of deceased 66.1±8.8 years) and post-acute period (average duration of illness 43.22 days, age of deceased 67,0±5.9 years) of the disease, the presence of capillary congestion (CC) in 77,4%, pulmonary fibrosis (PF) in 32,2%, hemorrhages in 38,7%, thrombosis of small veins in 25,8%, organizing pneumonia in 41,93%, in 16,1% bacterial and fungal (Aspergillus) coinfection can be observed histopathologically. Diffuse alveolar damage was noted in 90.32%. The probability of the occurrence of CC is significantly higher in the post-acute period of the disease than in the acute period (the observed value of the T-criterion is 1.7454 with a critical value of 1.6991), and the occurrence of secondary co-infection in the acute and post-acute period of the disease does not differ significantly (the observed value T-criterion is equal to 1.0089 with a critical 1.6991). PF occurs in both periods of the disease, but there is no statistically significant relationship between the period of the disease and the probability of the occurrence of PF (p-value of the significance of the binomial test: it is 0.359 for the acute period and 0.146 for the post-acute). Also, there is no significant relationship between the use of respiratory support and detected PF in the acute (p=0.238) and post-acute (p=0.302) periods of severe COVID-19. The risk of hemorrhages in both periods is the same (p-value of the binomial test: 0.167 for the acute period, 1.000 for the post-acute period), but the probability of vein thrombosis in the acute period is significantly higher than the probability of occurrence in the post-acute period (the observed value of the T-criterion 2 .0897 at the critical 1.6991).