Fatal cases after Omicron BA.1 and BA.2 infection: results of an autopsy study

Objectives

Omicron lineages BA.1/2 are considered to cause mild clinical courses. Nevertheless, fatal cases after those infections are recognized but little is known about risk factors.

Methods

Twenty-three full and three partial autopsies in deceased with known Omicron BA.1/2 infections have been consecutively performed. The investigations included histology, blood analyses and molecular virus detection.

Results

COVID-19-associated diffuse alveolar damage (DAD) was found in only eight cases (31%). This rate is significantly lower compared to previous studies, including non-Omicron variants, where rates between 69% and 92% were observed. Neither vaccination nor known risk factors were significantly associated with a direct cause of death by COVID-19. Only those patients who were admitted to the clinic due to COVID-19 but not for other reasons had a significant association with a direct COVID-19 caused death (P > 0.001).).

Conclusions

DAD still occurred in the Omicron BA.1/BA.2 era but at considerably lower frequency than seen with previous variants of concern. None of the known risk factors discriminated the cases with COVID-19-caused death from those that died due to a different disease. Therefore, the host's genomics might play a key role in this regard. Further studies should elucidate the existence of such a genomic risk factor.