Line Dam Heftdal1,2, Martin Schultz3, Theis Lange4, Andreas Dehlbæk Knudsen1, Kamille Fogh5, Rasmus Bo Hasselbalch5, Christine Borgen Linander6, Thomas Kallemose6, Henning Bundgaard7,8, Kirsten Grønbæk2,8,9, Palle Valentiner-Branth10, Kasper Iversen5,8,11, Susanne Dam Nielsen1,8,12. 1. Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. 2. Department of Hematology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. 3. Department of Internal Medicine, Geriatric Section, Herlev-Gentofte University Hospital, Herlev, Denmark. 4. Department of Public Health, University of Copenhagen, Copenhagen, Denmark. 5. Department of Cardiology, Herlev-Gentofte University Hospital, Herlev, Denmark. 6. Department of Clinical Research, Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark. 7. Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. 8. Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark. 9. Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark. 10. Division of Infectious Diseases Preparedness, Statens Serum Institut, Copenhagen, Denmark. 11. Department of Emergency Medicine, Herlev-Gentofte University Hospital, Herlev, Denmark. 12. Department of Surgical Gastroenterology and Transplantation, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
Abstract
BACKGROUND: Coronavirus disease 2019 (COVID-19) vaccines are implemented worldwide in efforts to curb the pandemic. This study investigates the risk of a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcriptase polymerase chain reaction (RT-PCR) test following BNT162b2 vaccination in a large real-life population in Denmark. METHODS: Vaccination status and positive SARS-CoV-2 RT-PCR results from adults in the Capital Region of Denmark (n = 1 549 488) were obtained from national registries. PCR testing was free and widely available. The number of positive PCR tests per individual at risk was calculated as weekly rates. Time to positive PCR test was modelled using Kaplan-Meier methods and hazard ratios (HRs) were calculated using Cox regression. RESULTS: A total of 1 119 574 individuals received the first dose of BNT162b2 and 1 088 879 received a second dose of BNT162b2. Individuals were followed up to 8.7 months after first dose (median: 5.5 months; interquartile ratio: 4.1-8.7). Rates of PCR-confirmed SARS-CoV-2 infection 2-4 months after the second dose were 0.21, 0.33, and 0.36 per 1000 individuals per week at risk for July, August, and September, respectively. Four or more months after the second dose, the rates were 0.56, 0.76, and 0.53 per 1000 individuals per week at risk for July, August, and September, respectively. HR of SARS-CoV-2 infection after the second dose was 0.2 (95% confidence interval, .05-.48; P = .001) for individuals with 8 months' follow-up. CONCLUSIONS: Individuals who received 2 doses of the BNT162b2 COVID-19 vaccine had a low risk of breakthrough infection after up to 8 months of follow-up. However, there was a tendency toward higher rates with longer follow-up.
BACKGROUND: Coronavirus disease 2019 (COVID-19) vaccines are implemented worldwide in efforts to curb the pandemic. This study investigates the risk of a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcriptase polymerase chain reaction (RT-PCR) test following BNT162b2 vaccination in a large real-life population in Denmark. METHODS: Vaccination status and positive SARS-CoV-2 RT-PCR results from adults in the Capital Region of Denmark (n = 1 549 488) were obtained from national registries. PCR testing was free and widely available. The number of positive PCR tests per individual at risk was calculated as weekly rates. Time to positive PCR test was modelled using Kaplan-Meier methods and hazard ratios (HRs) were calculated using Cox regression. RESULTS: A total of 1 119 574 individuals received the first dose of BNT162b2 and 1 088 879 received a second dose of BNT162b2. Individuals were followed up to 8.7 months after first dose (median: 5.5 months; interquartile ratio: 4.1-8.7). Rates of PCR-confirmed SARS-CoV-2 infection 2-4 months after the second dose were 0.21, 0.33, and 0.36 per 1000 individuals per week at risk for July, August, and September, respectively. Four or more months after the second dose, the rates were 0.56, 0.76, and 0.53 per 1000 individuals per week at risk for July, August, and September, respectively. HR of SARS-CoV-2 infection after the second dose was 0.2 (95% confidence interval, .05-.48; P = .001) for individuals with 8 months' follow-up. CONCLUSIONS: Individuals who received 2 doses of the BNT162b2 COVID-19 vaccine had a low risk of breakthrough infection after up to 8 months of follow-up. However, there was a tendency toward higher rates with longer follow-up.
Authors: Bas Calcoen; Nico Callewaert; Aline Vandenbulcke; Winnie Kerstens; Maya Imbrechts; Thomas Vercruysse; Kai Dallmeier; Johan Van Weyenbergh; Piet Maes; Xavier Bossuyt; Dorinja Zapf; Kersten Dieckmann; Kim Callebaut; Hendrik Jan Thibaut; Karen Vanhoorelbeke; Simon F De Meyer; Wim Maes; Nick Geukens Journal: Viruses Date: 2022-06-09 Impact factor: 5.818