ABSTRACT
Background Infection breakthrough after COVID-19 vaccination is a point of conflict in current literature not only because of the estimation of the potential hazards and symptoms severity but also due to establishing a vaccination policy and measuring the extent of immunity after vaccination in addition to the waning of the humoral immunity over time. To our knowledge, this is the first study to stratify the risk of post-COVID-19 vaccination breakthroughs in Upper Egypt. Methods In this cross-sectional observational study, we enrolled 369 vaccinated patients registered in our facility either admitted or in out-patient clinic. Patients were interviewed and any proven history of COVID-19 infection after vaccination was recorded. Results In the current study, 18.97% (70 patients) of the 369 subjects enrolled in the study had COVID-19breakthrough infection. Students were the high-risk group representing 18.6% of the study subjects. Hypertension, diabetes, and cardiac disease were the most comorbidities associated with a prevalence of 15.7%, 8.6%, and 4.3% respectively. Prior to COVID-19, confirmed infection was present in 42.9% of the study group. Fever, headache, myalgia, and cough were among the most common symptoms of the post-COVID vaccination breakthrough with a prevalence of 90%, 75.7%, 84.3%, and 74.3% respectively. Conclusion Breakthrough infection after COVID-19 vaccination is not uncommon. Most cases are mild and don't require hospitalization. All types of vaccines tested in the current study offer adequate immunity and guard against severe COVID-19 infection. We encourage the current global policy of full vaccination. Trial registration ClinicalTrials.gov. NCT05033834. Registered September 5, 2021. COVID-19 Infection in After Vaccination-Full Text View-ClinicalTrials.gov.