Vaccination against novel Coronavirus (SARS-CoV-2) become highly recommended. In Iraq, three vaccines are available. They are Pfizer-Biontech, Oxford-AstraZenica, and Sino harm vaccines. A cross-sectional retrospective study was performed to a total of 2399 individual who are vaccinated with one of the available vaccines. People who are infected with Covid-19 before and/or after vaccination of either studied SARS-CoV-2 vaccines were also involved in this study (1175 case). Signs and symptoms have been reported for each of confirmed positive cases of Coronavirus disease. Statistical data analyses were applied to reveal the effect of different SARS-CoV-2 vaccines on the incidence of novel coronavirus disease among Iraqi population. Also, the virulence of novel SARS infection after vaccination was determined in response to sings and symptoms of the disease. Pfizer-BioNTech and Sino pharm vaccines show the least percentage (5.1%; 34 and 6.5%; 13) of disease incidence after first dose of vaccination respectively, while Oxford- AstraZenica show the highest percentage 11.5%; 39. In respect to SARSCoV-2 infection after second dose of vaccination, Pfizer-BioNTech percentage are the least (4.5%), Sinopharm (16.5%) and Oxford- AstraZenica (18.0%). The study concluded that incidence of Covid-19 was decreased after second dose vaccination of Pfizer, Sinopharm and AstraZenica vaccines respectively. Oxford-AstraZenica shows the least efficacy upon incidence of Covid-19 than Pfizer-Biontech and Sinopharm vaccines, after first and second dose vaccination, and severity of the symptoms after second dose vaccination.