Comparative IgG Antibody Titers Following Second Dose of Sinopharm and Pfizer Vaccination

<p><strong>Background and Objective: </strong>The vaccines Sinopharm and Pfizer account for more than 7.3 billion vaccinations across the globe. Study data shows that the protection offered by these vaccines wanes with time, which is why the third dose of a different or same vaccine may become necessary. The objective of this study was to compare the levels of IgG in the post-vaccination phase, with two different vaccines, Sinopharm and Pfizer.&nbsp;&nbsp;</p> <p><strong>Methodology: </strong>A cross sectional study was conducted at CMH Lahore Medical College and Institute of Dentistry, after approval by the Ethical committee. A total of 100 participants, who were completely vaccinated, with either Sinopharm or Pfizer, at least six weeks before, were included in the study. Participants with concurrent infection, incomplete vaccination or any known disease, were excluded from the study. Written consent was obtained from all the participants. A predesigned questionnaire, adapted from similar studies, was used for data collection. Afterwards, blood samples were collected and IgG antibody levels were estimated using RD-RatioDiagnostics SARS-COV-2 virus IgG ELISA kit (E-COG-K105). The collected data was analyzed with SPSS software. Results with p value &lt; 0.05 were taken as significant.</p> <p><strong>Results: </strong>Mean age of the participants was 20.18&plusmn;1.29 years. Mean antibody titers, six weeks post-vaccination, were 5453.73&plusmn;609.15 U/ml and 10786.86&plusmn;1525.49 U/ml in Sinopharm and Pfizer groups, respectively. The difference was statistically significant (p=0.0004).</p> <p><strong>Conclusion: </strong>Antibody response is considerably higher in Pfizer-vaccinated individuals, in comparison to Sinopharm.</p>