Comparison of Clinical Characteristics and Outcome Between Vaccinated and Non-Vaccinated Patients of Covid-19 During the Delta Variant-Dominated Fourth Wave in a Tertiary Care Hospital in Karachi, Pakistan.

Introduction In Pakistan, the fourth wave of coronavirus disease 2019 (Covid-19) started around July 2021, which was dominated by the Delta variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The vaccination drive to immunize the people of Pakistan against Covid-19 was also going on during this period. There were multiple types of vaccines being administered to the people of Pakistan, as the vaccines had been procured from multiple sources. Some people had apprehensions about different vaccines being administered in the country. The purpose of this study was to compare the clinical characteristics and outcome of the patients vaccinated against Covid-19 with those of the non-vaccinated patients during the fourth wave of Covid-19 in Pakistan Naval Ship (PNS) Shifa Hospital. Methods The cross-sectional descriptive study was performed at PNS Shifa Hospital Karachi, from July to October 2021. All the Covid-19 patients treated in PNS Shifa Hospital during the "fourth Covid-19 wave" were interviewed. Their medical records were accessed, and they were followed up till their discharge from the hospital. The vaccinated and non-vaccinated patients were compared for differences in their age or gender distribution, the severity of illness, comorbidities, and mortality. Results There were 884 participants in the study: 664 (75.11%) men and 220 (24.89%) women. There were 493 patients below 40 years of age, 233 were 40-59 years old, and 158 were aged 60 and above. One hundred and sixty-nine patients had one or more comorbidities, including hypertension, diabetes mellitus, ischemic heart disease, various malignancies, bronchial asthma, and chronic kidney disease. There were 63 (7.13%) obese patients, 28 of whom developed severe disease. Five hundred and four (57%) patients were vaccinated and 380 (47%) were non-vaccinated. Among the vaccinated patients, the effect of Covid-19 was mild in 58.37%, moderate in 36.11%, severe in 0.79%, and critical in 4.37%. Among the non-vaccinated patients, the effect of Covid-19 was mild in 40.26%, moderate in 46.58%, severe in 3.16%, and critical in 10%. The difference in disease severity between the two groups was statistically significant (