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Article

COVID-19 Breakthrough Infections and Transmission Risk: Real-World Data Analyses from Germany’s Largest Public Health Department (Cologne)

1
Public Health Department Cologne, Infektions- und Umwelthygiene, 50667 Köln, Germany
2
Institute for Occupational Medicine and Social Medicine, University Hospital, Medical Faculty, RWTH Aachen University, 52056 Aachen, Germany
3
Department for Physical Activity in Public Health, Institute of Movement and Neurosciences, Am Sportpark Müngersdorf 6, German Sport University Cologne, 50933 Cologne, Germany
4
Institute of Hygiene, University Hospital Muenster, 48149 Münster, Germany
*
Author to whom correspondence should be addressed.
Those authors contributed equally.
Academic Editor: Ralph A. Tripp
Vaccines 2021, 9(11), 1267; https://doi.org/10.3390/vaccines9111267
Received: 5 October 2021 / Revised: 22 October 2021 / Accepted: 29 October 2021 / Published: 2 November 2021
Background and Methods: Vaccination is currently considered the most successful strategy for combating the SARS-CoV-2 virus. According to short-term clinical trials, protection against infection is estimated to reach up to 95% after complete vaccination (≥14 days after receipt of all recommended COVID-19 vaccine doses). Nevertheless, infections despite vaccination, so-called breakthrough infections, are documented. Even though they are more likely to have a milder or even asymptomatic course, the assessment of further transmission is highly relevant for successful containment. Therefore, we calculated the real-world transmission risk from fully vaccinated patients (vaccination group, VG) to their close contacts (CP) compared with the risk from unvaccinated reference persons matched according to age, sex, and virus type (control group = CG) utilizing data from Cologne’s health department. Results: A total of 357 breakthrough infections occurred among Cologne residents between 27 December 2020 (the date of the first vaccination in Cologne) and 6 August 2021. Of the 979 CPs in VG, 99 (10.1%) became infected. In CG, 303 of 802 CPs (37.8%) became infected. Factors promoting transmission included non-vaccinated status (β = 0.237; p < 0.001), male sex (β = 0.079; p = 0.049), the presence of symptoms (β = −0.125; p = 0.005), and lower cycle threshold value (β = −0.125; p = 0.032). This model explained 14.0% of the variance (corr. R2). Conclusion: The number of transmissions from unvaccinated controls was three times higher than from fully vaccinated patients. These real-world data underscore the importance of vaccination in enabling the relaxation of stringent and restrictive general pandemic control measures. View Full-Text
Keywords: COVID-19; vaccination; breakthrough infections; SARS-CoV-2 pandemic; SARS-CoV-2 transmission COVID-19; vaccination; breakthrough infections; SARS-CoV-2 pandemic; SARS-CoV-2 transmission
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MDPI and ACS Style

Hsu, L.; Grüne, B.; Buess, M.; Joisten, C.; Klobucnik, J.; Nießen, J.; Patten, D.; Wolff, A.; Wiesmüller, G.A.; Kossow, A.; Hurraß, J. COVID-19 Breakthrough Infections and Transmission Risk: Real-World Data Analyses from Germany’s Largest Public Health Department (Cologne). Vaccines 2021, 9, 1267. https://doi.org/10.3390/vaccines9111267

AMA Style

Hsu L, Grüne B, Buess M, Joisten C, Klobucnik J, Nießen J, Patten D, Wolff A, Wiesmüller GA, Kossow A, Hurraß J. COVID-19 Breakthrough Infections and Transmission Risk: Real-World Data Analyses from Germany’s Largest Public Health Department (Cologne). Vaccines. 2021; 9(11):1267. https://doi.org/10.3390/vaccines9111267

Chicago/Turabian Style

Hsu, Lea, Barbara Grüne, Michael Buess, Christine Joisten, Jan Klobucnik, Johannes Nießen, David Patten, Anna Wolff, Gerhard A. Wiesmüller, Annelene Kossow, and Julia Hurraß. 2021. "COVID-19 Breakthrough Infections and Transmission Risk: Real-World Data Analyses from Germany’s Largest Public Health Department (Cologne)" Vaccines 9, no. 11: 1267. https://doi.org/10.3390/vaccines9111267

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