Logistic regression analysis was performed to investigate predictors of change in anti-S protein IgG antibody status after the 1st dose and after the second dose. == Among the participants, 69% (n = Pyrantel pamoate 250) reported at least one vaccine-related sign. Pain in the injection site was the most frequently reported vaccine-related sign. The mean total score for vaccine-related symptoms was significantly higher among participants who received the AstraZeneca vaccine, women, and participants with no earlier COVID-19 illness (p< 0.05). Spike-specific IgG antibodies were recognized in 98.9% of participants after the receipt of two vaccine doses, including 99.5% of Pfizer vaccine recipients and 98.3% of AstraZeneca vaccine recipients. Significantly, higher proportions of participants in the <35-yr age group developed a humoral immune response after the 1st vaccine dose compared with the participants in additional age groups. == Summary == Participants who received the Pfizer COVID-19 vaccine reported fewer vaccine-related complications compared with those who received the AstraZeneca COVID-19 vaccine, but no severe side effects were reported in response to either vaccine. Health status and age were factors that may influence COVID-19 vaccine performance for the generation of antibodies against the SARS-CoV-2 spike protein. Keywords:reactogenicity, immunogenicity, Pfizer, AstraZeneca, vaccines, Saudi Arabia == Intro == Coronavirus disease 2019 (COVID-19) offers rapidly become a leading cause of death and both short- and long-term morbidity among individuals more than 45 years (1,2), representing an extraordinary problem for healthcare organizations and causing global economic issues and prolonged lockdowns (3). Although COVID-19 vaccine effectiveness and safety have been reported in recent studies (46), the current scenario in Saudi Arabia has not been reported. Commonly, individuals with any history of prior COVID-19 illness, for whom vaccination is definitely presently recommended (https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq.html, accessed about 11 October 2021), were omitted from vaccine-related Pyrantel pamoate clinical tests. Although previous illness with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease is thought to provokes a natural immunity that is durable for at least 6 months (7), whether previous SARS-CoV-2 illness is associated with vaccination side effects has not been identified (8). Vaccines are desired Pyrantel pamoate for controlling the spread of SARS-CoV-2 infections. COVID-19 vaccination, combined with additional illness transmission prevention methods, is definitely necessary to prevent SARS-CoV-2 infections from distributing in the community, especially among those with immune disorders and health care workers who are fighting the disease on the front lines (9). Among the currently authorized COVID-19 vaccines, the AstraZeneca vaccine is an adenovirus-based vector vaccine, and Pyrantel pamoate the Pfizer/BioNTech and Moderna vaccines are mRNA vaccines, all of which have been used in several settings, including Saudi Arabia (https://www.moh.gov.sa/en/Ministry/HotTopics/Pages/COVID-19-Vaccine.aspx, accessed on 11 October 2021). The AstraZeneca and Pfizer/BioNTech vaccines have shown an immunogenic nature accompanied by significant performance for avoiding COVID-19 disease (4,10). The mRNA-based Pfizer/BioNTech vaccine was the 1st vaccine to receive approval for use in Saudi Arabia in mid-December 2020, and the adenovirus-vectored AstraZeneca vaccine was the second vaccine to be approved in February 2021 (11). Although these vaccines efficiently decrease the severity of the SARS-CoV-2 illness (12,13), initial investigations of reactogenicity showed Kv2.1 (phospho-Ser805) antibody that transitory local responses were common and systemic episodes were rare following vaccination (14). One recent national study examined the reactogenicity of the AstraZeneca vaccine by collecting data from participants over the phone (15). However, dual comparative investigations of reactogenicity and immunogenicity between authorized vaccines in Saudi Arabia have not been performed. In the current study, we targeted to assess the reactogenicity and immunogenicity among adults in response to receiving both doses of the Pfizer and AstraZeneca vaccines and correlate the reactogenicity profiles and induction of humoral immunity with the characteristics of the participants. == Materials and Methods == == Study Design and Human population == This cross-sectional study recruited adult participants aged 18 years or older who received both doses of either the Pfizer or AstraZeneca COVID-19 vaccine and went to the vaccine center at Taibah University or college between February 1 and June 30, 2021. In accordance with recommendations, the time between the 1st and second Pfizer vaccinations was 3 weeks, whereas 12 weeks separated the administration of the AstraZeneca doses. The study was advertised in the vaccine center, and banners were placed in the waiting rooms. Initially, data were collected from Pyrantel pamoate 952 individuals who agreed to participateviaan online survey. Participants were invited to an in-person check out, at which missing data were acquired, and a blood sample was collected. Individuals who reported recent contact with COVID-19infected individuals were excluded. Written educated consent was from each participant before any personal data.
