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Severe COVID-19 outcomes during Omicron were extremely impacted by underlying health conditions.

Researchers conducted a retrospective study published in June 2025 issue of BMC Infectious Disease to compare mortality and hospitalization risks from COVID-19 during the Omicron era between individuals with comorbidities and those without.   

They performed a systematic search across 7 databases [Embase, MEDLINE, PubMed, Europe PMC, Latin American and Caribbean Health Sciences Literature, Cochrane COVID-19 Study Register, WHO COVID-19 Database] for studies published between January 2022 and March 2024. Included studies involved individuals with at least 1 comorbidity: cardiovascular or cerebrovascular disease, chronic lung conditions, diabetes, or obesity. Data was pooled using random-effects models. Outcomes assessed included risk of death, hospitalization, intensive care unit (ICU) admission, and composite endpoints.   

The results showed that 68 out of 72 studies were included in the meta-analysis. Participant counts per comorbidity ranged from 3,28,870 to 13,720,480. Increased risks of death, hospitalization, and combined outcomes were observed in individuals with cerebrovascular disease, chronic obstructive pulmonary disease, diabetes, respiratory diseases, heart disease, and heart failure, with pooled relative risk (RR) ranging from 1.27 [heart disease, hospitalization; 95% CI: 1.17–1.38] to 1.78 [heart failure, death; 95% CI: 1.46–2.16]. Diabetes and obesity were linked to elevated ICU admission risk (RR: 1.20, 95% CI: 1.04–1.38; RR: 1.32, 95% CI: 1.11–1.57, respectively).   

Investigators concluded that individuals with comorbidities experienced higher risks of severe COVID-19 outcomes during the Omicron era. 

Source: ijidonline.com/article/S1201-9712(25)00182-1/fulltext