Vaccination Against COVID-19 in Comorbid Patients

Background: The coronavirus disease 2019 (COVID-19) has become one of the deadliest pandemics in recent history. Despite the introduction of preventive measures such as physical distancing, wearing masks, remote work, isolation, and quarantine to slow the spread, these behavioral measures have had undesirable consequences, including negative psychological effects, deep depression, and other mental health issues. The development of a safe and effective vaccine emerged as the most promising strategy for combating COVID-19. Today, vaccination remains one of the most effective tools to fight against COVID-19. Objectives: The aim of this study was to analyze the clinical and laboratory differences between vaccinated and unvaccinated patients hospitalized for pneumonia caused by COVID-19. Methods: The study included patients admitted to the clinic with COVID-19 between January 2021 and October 2021. Demographics, clinical features, and treatment outcomes were recorded. Additionally, the vaccination status of patients against COVID-19 was documented. The cases were divided into two groups: Those who had received the COVID-19 vaccine and those who had not. Complete vaccination was defined as receiving two doses (0.5 mL) intramuscularly with the last dose administered at least 14 days prior or receiving two doses (0.3 mL) intramuscularly with the last dose administered at least 21 days prior, and no more than 6 months after the last dose. The vaccines included in the study were Pfizer, QazVac, Sinopharm/Beijing, Sinovac, and Sputnik V. Results: In total, 510 cases were included in the study, divided into two groups based on vaccination status: 367 unvaccinated cases and 143 vaccinated cases. The unvaccinated group had a longer duration of hospitalization than the vaccinated group (9 days vs. 7 days, respectively) (P < 0.001). Although no differences were found between the two groups regarding the nature of the radiological lesions, the number of affected areas was significantly greater in the unvaccinated group (P < 0.05). There was no statistically significant difference in the number of complications between the two groups (97.9% in the vaccinated group, n = 140/143; 99.2% in the unvaccinated group, n = 364/367). In terms of mortality, 9.8% (14/143) of the vaccinated group died, compared to 21.3% (78/367) in the unvaccinated group, with a statistically significant difference (P = 0.002). When assessing the SPO2 index at admission, statistically significant differences were observed (P < 0.001). Biochemical parameters such as urea, albumin, glucose, and creatinine were significantly higher in unvaccinated patients (urea: 4.2 ± 19.3; creatinine: 9.8 ± 18.5). Serum levels of C-reactive protein (CRP) and procalcitonin (PRK) were significantly higher in the vaccinated cases. Interleukin-6 (P < 0.001), troponin (P < 0.001), ferritin (P = 0.002), and D-dimer (P < 0.001) were significantly elevated in the unvaccinated group. Conclusions: Vaccinated patients infected with COVID-19 had shorter hospital stays and less severe radiological lesions. The levels of severe COVID-19 predictors such as CRP, IL-6, D-dimer, and ferritin were statistically significant in the unvaccinated group. The mortality rate was higher in the unvaccinated group compared to the vaccinated group. Vaccination appears to be highly effective in mitigating the effects of COVID-19 in patients with chronic comorbidities and significantly reduces mortality in these patients.