A case series of severe breakthrough infections observed in nine patients with COVID-19 in a southwestern German university hospital

Purpose Vaccination is the key element for protection against COVID-19. Increased vaccination breakthroughs raise the question of whether additional prevention is necessary in case of individual risk factors for a severe course with hospitalization or death despite vaccination. Methods Since July 13, 2021, there is an extended reporting requirement by German law. We analyzed our hospitalized patients with vaccine breakthrough infection during the first 8 weeks. Results Nine of 67 patients (13.4%) hospitalized for COVID-19 (median age 75 years) were fully vaccinated. Five of these patients received intensive care; two patients died. All had received two doses of BNT162b2 vaccines (Pfizer-BioNTech). There was a median of 99 days between complete immunization and symptom onset. All patients suffered from ≥ three comorbidities. Six patients (66.7%) showed a negative Anti-SARS-CoV-2-N titer at the time of vaccine breakthrough, five of these also had Anti-SARS-CoV-2-S titers