Older age, lack of vaccination and infection with variants other than Omicron associated with severity of COVID-19 and in-hospital mortality in Pakistan

Objectives We investigated factors associated with COVID-19 disease severity and in-hospital mortality in a low-middle income setting. Methods Records of 197 adult COVID-19 patients admitted to the Aga Khan University Hospital, Karachi between April 2021 and February 2022 were reviewed. Clinical data including, that of SARS-CoV-2 variants was collected. Results The median age of the patients was 55 years and 51.8% were males. 48.2 % of patients had non-severe disease, while 52.8% had severe/critical disease. Hypertension (48%) and diabetes mellitus (41.3%) were most common comorbid conditions. Omicron (55.3%), Beta (14.7%), Alpha (13.7%), Delta (12.7%) and Gamma (3.6%) were identified in patients. The risk of severe disease was higher in those aged above 50 years (OR 5.73; 95%CI [2.45-13.7]) and in diabetics (OR 4.24; 95% CI[1.82-9.85]). Full vaccination (OR 0.25; 95%CI [0.11-0.58]) or infection with Omicron variants (OR 0.42; 95% CI[0.23-0.74]) reduced disease severity. Age > 50 (OR 5.07; 95%CI [1.92-13.42]) and presence of myocardial infarction (OR 5.11; 95% CI[1.45-17.93]) was associated with increased mortality, but infection with Omicron (OR 0.22 95% CI 0.10-0.53]) reduced risk. Conclusions Vaccination was found to protect against severe COVID-19 regardless of the infecting variant and is recommended especially, in those aged over 50 years and with co-morbid conditions.