Severity of SARS-CoV-2 infection among vaccinated individuals: A hospital-based study.

Introduction: Post-vaccination infections impart the need for real-world data on protection conferred by the vaccines against SARS-CoV-2. We aimed to evaluate the severity of post-vaccination COVID-19 and the predictors of severe disease.

Methods: This cross-sectional study analysed data from 307 patients admitted to the University Hospital KDU with confirmed COVID- 19 from March 1st to November 1st, 2021, after receiving at least a single dose of a vaccine against SARS-CoV-2. Vaccination status and the disease severity were classified using standard definitions. A binary logistic regression model was fitted to investigate severe/critical disease predictors.

Results: Of the surveyed patients, 122(39.7%) were fully vaccinated, 127(41.4%) were partially vaccinated and 58 (18.9%) had developed the disease within 14 days of the first vaccine dose. Most were Sinopharm vaccine recipients (52.4 %). Non- severe disease was observed among 249(81.1%) patients and 47(15.3%) had severe disease, while 11(3.6%) needed ICU care (critical illness). Severe/critical disease was reported among 32(25.2%) partially vaccinated and 13(22.4%) patients who developed the disease within 14 days of the first vaccine dose. Of the patients deemed to have vaccine breakthrough infections (122 fully vaccinated patients), 13(10.6%) suffered severe/critical disease. Patients with comorbidity experienced more severe/critical illness (adjusted odds ratio [AOR]= 3.684, P=0.003) than those without pre-existing medical conditions. Disease progression to severe or critical illness was significantly higher among Sinopharm recipients than Covisheild recipients (AOR:2.064, P=0.048).

Conclusions: Comorbidity was the most important predictor of severe COVID-19 irrespective of the vaccination status. Observed higher incidence of severe disease among Sinopharm recipients warrants more extensive population studies.