Increasing Levels of Serum Anti-Spike S۱-RBD IgG after ۱۲۰ Days of the Pfizer-BioNTech-mRNA Second Dose Vaccination

Severe acute respiratory syndrome coronavirus ۲ (SARS-CoV-۲) mRNA vaccines, such as Pfizer-BioNTech, have demonstrated high efficacy; however, there is limited data on the duration of immune responses besides their relationships with age, gender, body mass index (BMI), and the presence of previous coronavirus disease-۲۰۱۹ (COVID-۱۹) infection. This study aimed to evaluate SARS-COVID-۱۹ Anti-Spike IgG levels after ۳۰ days (one month) and ۱۲۰ days (four months) of the ۲nd dose of Pfizer-BioNTech vaccine given to medical students at Al-Iraqi University, Baghdad, Iraq. This study was performed after the obtainment of the acceptance and approval of the Medical College of Al-Iraqi University and the Iraqi Ministry of Health. Two groups of students were randomly picked up from the Medical College of Al-Iraqi University. They were completely vaccinated by administering two doses of Pfizer-BioNTech/۰.۵ ml for each dose. After taking their permission,  ۵ ml of their blood (one group after one month and the second group after four months of vaccination) was drawn in the Higher Education lab inside the Medical College of Al-Iraqi University. It took approximately four months to collect the samples (from October ۲۰۲۱ until February ۲۰۲۲). Following that, serological analysis was done for measuring the SARS-CoV-۲ spike protein IgG by using Elabscience/SARS-CoV-۲ spike protein IgG ELISA Kit (USA) (+ve <۰.۰۶) that was performed in the Higher Education lab of Medical College of Al-Iraqi University. Demographic data were also collected from participants, including age, gender, BMI, blood group, and the presence of previous COVID-۱۹ infection. For statistical analysis, SPSS (version ۲۶) and STATISTICA (version ۱۲) were used to input, check, and analyze data. Standard approaches of frequencies and percentages were used for qualitative variables, while for quantitative variables, mean±standard deviation was used. A P-value of <۰.۰۵ was considered a significant plasma level of the SARS-COVID-۱۹ Anti-Spike IgG. The study results showed that in group ۱ (after one month of the ۲nd dose), the male-female ratio was ۶۲.۲: ۳۷.۸, the mean age of the vaccinated students was ۲۸.۲۰۰۰ years old, and the BMI was ۲۵.۵۴۵۴ kg/m۲ with ۳۳.۳% previously COVID-۱۹ infected individuals. In group ۲ (after four months of the ۲nd dose), the male-female ratio was ۴۴.۴: ۵۵.۶, the mean age of the vaccinated students was ۲۵.۸۴۴۴ years old, and the BMI was ۲۴.۷۵۸۴ kg/m۲ with ۲۴.۴% previously COVID-۱۹ infected individuals. The plasma levels of SARS-COVID-۱۹ Anti-Spike IgG after the ۲nd dose of the Pfizer-BioNTech vaccine in group ۱ (one month) and group ۲ (four months) were statistically non-parametric. Once the independent two samples Mann-Whitney test was used, a significant difference (P<۰.۰۵) was observed in SARS-COVID-۱۹ Anti-Spike IgG plasma levels after ۳۰ days of the ۲nd dose of the Pfizer-BioNTech vaccine administration, compared to the ۱۲۰ days of administration. In conclusion, SARS-COVID-۱۹ Anti-Spike IgG levels significantly increased in group ۲ (four months after the ۲nd dose of the Pfizer-BioNTech vaccine), compared to group ۱ (one month after the ۲nd dose of the Pfizer-BioNTech vaccine).

Keywords:

SARS-COVID-۱۹ Anti-Spike IgG , Pfizer-BioNTech vaccine , Medical students , Al-Iraqi University