A study on the side effects caused by the Pfizer/BioNTech COVID-19 vaccine: Focus on IgG antibodies and serological biomarkers.

Introduction: The SARS-CoV-2 pandemic that spread swiftly is now a major global public health issue. Vaccines are currently being distributed in an effort to limit the viral transmission and mortality. The aim of the study was monitoring of both safety and efficacy in determining the overall effectiveness of the vaccine and identifying any potential safety concerns.

Material and methods: A retrospective, cross-sectional study employing a validated 13-item structured questionnaire divided into two sections was performed between March 2022 and September 2022. Different post-vaccination side effects (SE) according to symptoms severity in terms of age and sex for participants were reported. Additionally, some pertinent serological assays for participants' post-vaccinations were investigated.

Results: A total of 502 participants (male: 262, female: 240) with comorbidity (healthy: 258, morbid: 244) who received two Pfizer/BioNTech mRNA vaccine doses were included. Importantly, second dose (D2) vaccination was associated with significantly more SE than single dose (D1) vaccination (p < 0.0001). In D1 vaccination injection site pain (ISP) (45%), followed by equal proportions of headache and fever (40%) were the most common vaccine SE, while in D2 vaccination, ISP (66%) and nausea (57%) were reported. In all, 97% (p < 0.0001) of participants were IgG antibody positive at D2 vaccination. Similarly, serum CR protein level was elevated significantly (p < 0.0001) corresponding to the severity of SE between D1 and D2. Significant differences in IgG concentration were found between D1 and D2 vaccination in different gender and age groups (p < 0.0001).

Conclusions: In light of the extensive data from this study, it is evident that mRNA vaccines, particularly the Pfizer/BioNTech vaccine, have proven to be highly safe and effective in mitigating the impact of the SARS-CoV-2 pandemic.