en علوم آزمایشگاهی Laboratory پژوهشي Original Research <div style="text-align: justify;"><span style="font-size:14px;"><span style="font-family:Tahoma;"><span style="line-height:2;"><span sans-serif=""><span new="" roman="" times=""><strong>Background</strong>: The availability of the COVID-19 vaccine during the pandemic has changed the disease course in the entire world. The current study aimed to compare various hematological parameters among COVID-19 patients with and without vaccination.<br> <strong>Methods</strong>: The present retrospective study included 26 vaccinated and 26 non-vaccinated COVID-19 patients. Various clinical and biochemical parameters of RT-PCR-positive patients were collected. The values are expressed in Mean&plusmn;SD or median values IQR.&nbsp;Mann-Whitney U test was used for comparison between the groups.&nbsp;<br> <strong>Results</strong>: Among the vaccinated individuals, 17 cases (65.4%) were asymptomatic, one patient (3.8%) had moderate, eight cases (30.8%) had mild COVID-19 infection and all 26 patients were completely recovered.&nbsp;Among non-vaccinated COVID-19 patients,&nbsp;25 cases (96.2%) had severe, one case (3.8%) had moderate COVID-19, and 16 patients (61.5%) recovered but ten cases succumbed to COVID-19.&nbsp;There were&nbsp;statistically significant differences in SpO2, total leucocyte count, and differential counts of neutrophils, lymphocytes, eosinophils, monocytes, and basophils between vaccinated and non-vaccinated patients (P<0.001). The neutrophil/lymphocyte ratio was found to be at a higher level (P<0.01) among non-vaccinated patients [10.9(4.28-23.63)]&nbsp;&nbsp;compared to vaccinated [1.55(1.09-2.28)].&nbsp;The blood urea, total and direct bilirubin, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), and inflammatory markers, like&nbsp;C-reactive protein (CRP), D-dimer, ferritin, and lactate dehydrogenase (LDH)&nbsp;were highly elevated in non-vaccinated patients (P<0.001). Moreover, lower values of total protein, serum albumin, and albumin and globulin (A/G) ratio were noted in the non-vaccinated compared to vaccinated individuals (P<0.001).<br> <strong>Conclusion</strong>: Vaccinated patients had milder disease with fewer derangements of hematological parameters compared to non-vaccinated patients. It can be concluded that vaccine has played a vital role during the COVID-19 pandemic in reducing mortality.&nbsp;</span></span></span></span></span></div> COVID-19, Inflammatory markers, Neutrophil/Lymphocyte ratio, Retrospective studies, Vaccine. 45 52 http://pbr.mazums.ac.ir/browse.php?a_code=A-10-1094-1&slc_lang=en&sid=1 Mahalaxmi S Petimani mahalaxmi.petimani@gmail.com 100319475328460010272 100319475328460010272 No KAHER’s JGMM Medical College, Hubblli-580028, Karnataka, India. Prabhakar Adake dradake82@gmail.com 100319475328460010273 100319475328460010273 No KAHER’s JGMM Medical College, Hubblli-580028, Karnataka, India. Pavithra H pavithraymc@yenepoya.edu.in 100319475328460010274 100319475328460010274 No Department of Community Medicine, Yenepoya Medical College, Yenepoya (Deemed to be University), Karnataka, India. Drisya Kaladharan drishyak070@gmail.com 100319475328460010275 100319475328460010275 Yes Department of Biochemistry, Yenepoya Medical College, Yenepoya (Deemed to be University), Karnataka, India.