The Severity of COVID 19 Pneumonia in Vaccinated vs. Non-vaccinated Patients in the Second Wave: An Experience From a Tertiary Care Center in India

Background: Coronavirus disease 2019 (COVID-19) is a novel infectious disease caused by SARS CoV-2 that emerged in Wuhan, China, and has rapidly spread worldwide. The mortality rate of critically ill COVID-19 patients is high. Objective: To assess the severity, different clinical symptoms, and comorbidities of COVID-19 pneumonia in vaccinated vs. non-vaccinated patients. Methods: In this single-center, cross-sectional study, 142 patients with COVID-19 were enrolled. The clinical characteristics, comorbidities, severity, and outcomes were also assessed. Results: Of the 142 patients, 92 (64.8%) were males, with a mean age of (56.00±14.81) years. Among them, 62 (43.7%) were aged above 60 years. Of these, 92 (64.7%) had comorbidities. The patients were divided into two groups: unvaccinated and those who received at least one dose of the vaccine within six months. The demographic characteristics of the two groups were similar except for gender. In the vaccinated group, most of the patients were males. Most patients in the non-vaccinated group had a severe illness, whereas most patients in the vaccinated group had mild to moderate disease. Only 26% of the vaccinated group experienced severe illness compared to 71.5% in the unvaccinated group. In addition, the all-cause 30-day mortality in the non-vaccinated population was higher than that in the vaccinated population. However, this difference was not statistically significant (12.5% vs. 7.1%). On the contrary, there was no difference in the length of the intensive care unit or total hospital stay between the two groups. Conclusion: Severe COVID-19 had the worst outcome in the unvaccinated patients. Most partially vaccinated patients got infected before developing immunity, and a small percentage of completely immunized patients who were infected were likely non-responders. Receiving at least one vaccination dose significantly reduced illness severity.