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Background: The World Health Organization had declared the release of COVID-19 vaccines in September 2020 and after. mRNA vaccine “Pfizer Biotech” and the adenoviral vector vaccine CoV-19 (AstraZeneca-Oxford) were granted emergency use. Researchers found that effectiveness of AstraZeneca and Pfizer vaccine is (70% and 95%) respectively. While the inactivated SARS-CoV-2 vaccine (Sinopharm) is safe, effective (effectiveness more than 50%) as WHO's declared. Sinopharm was the first vaccine that had been administered to Iraqi population. Only 2% of population had been vaccinated despite the efficacy and acceptability of it. Several studies conducted in different countries to assess the effectiveness of Covid-19 vaccines and its safety.
Aim: This study done to assess the frequency of post vaccination infection with COVID-19 and accompanying signs and symptoms in different vaccine companies that are available in Iraq (Sinopharm, AstraZeneca-Oxford and Pfizer- BioNTech).
Patients and methods: The study is a cross-sectional study conducted from 11th November 2021 to 15th March 2022 that included 500 Iraqi persons vaccinated with COVID-19 vaccine with either Pfizer, AstraZeneca or Sinopharm, Patients were chosen by Convenient sampling from different Iraqi governorate. All data management and analysis done by manual statistical methods.
Results: From total 500 patients participated in the study with full doses vaccination (2 doses as recommended) there were (25%) person get covid-19 infection. Majority of infection occurred after 6 months of 2nd dose. Majority of postvaccination infections with Pfizer vaccine were with mild to moderate symptoms without need hospitalizations in comparison to (5.56%), (3.13%) hospitalizations rate and severe infection post AstraZeneca and Sinopharm vaccines respectively.
Conclusion: Full vaccination of two doses of (Pfizer, AstraZeneca, Sinopharm) are highly effective in decrease the severity of COVID-19 infection signs and symptoms, decrease rate of hospitalizations. High efficacy of Pfizer vaccine than AstraZeneca and Sinopharm vaccines .