Study design
This study was performed in the Wasit Province of Iraq Al-Zahra Teaching Hospital, between March – June 2022. 40 COVID-19+ patients (20 vaccinated with Pfizer-BioNTech COVID-19 vaccine and 20 unvaccinated) were studied during and after COVID-19 infection and 12 healthy and vaccinated controls (6 in each group) were also enrolled in this study. 30 were male and 22 were female participants in this study. Blood samples were collected over two time periods i.e.: during infection and 2-3 weeks after the onset of the disease. All individuals in this study provided an informed consent for enrollment.
Immunological, biochemical and serological and hematological tests were performed for all groups.
The inclusion criteria for the participants in the study were being adults (between 20-70 years old) hospitalized for at least seven days from the onset of COVID-19 symptoms, which is when usually the inflammatory phase begins, with a diagnosis of pneumonia due to COVID-19 based on clinical-radiological criteria and a laboratory PCR which confirmed SARS-CoV-2 infection diagnosis, oxygen saturation < 94% and 25(OH) D serum levels < 30 ng/ml. Vaccinated participants had received two doses of Pfizer BioNTech COVID-19 vaccine three to four months prior to the study.
Participants were excluded if they were lactating, pregnant women, were participating in other clinical trials with drugs with potential antiviral action for COVID-19, or diseases such as cancer, autoimmune disease, thalassemia and allergy.