SARS-CoV-2 Vaccine Alpha and Delta Variant Breakthrough Infections Are Rare and Mild but Can Happen Relatively Early after Vaccination

Jelissa Katharina Peter; Fanny Wegner; Severin Gsponer; Fabrice Helfenstein; Tim Roloff; Rahel Tarnutzer; Kerstin Grosheintz; Moritz Back; Carla Schaubhut; Sabina Wagner; Helena M B Seth-Smith; Patrick Scotton; Maurice Redondo; Christiane Beckmann; Tanja Stadler; Andrea Salzmann; Henriette Kurth; Karoline Leuzinger; Stefano Bassetti; Roland Bingisser; Martin Siegemund; Maja Weisser; Manuel Battegay; Sarah Tschudin Sutter; Aitana Lebrand; Hans H Hirsch; Simon Fuchs; Adrian Egli

doi:10.3390/microorganisms10050857

SARS-CoV-2 Vaccine Alpha and Delta Variant Breakthrough Infections Are Rare and Mild but Can Happen Relatively Early after Vaccination

Microorganisms. 2022 Apr 21;10(5):857. doi: 10.3390/microorganisms10050857.

Authors

Jelissa Katharina Peter¹, Fanny Wegner^{2

3

4}, Severin Gsponer¹, Fabrice Helfenstein⁵, Tim Roloff^{2

3

4}, Rahel Tarnutzer¹, Kerstin Grosheintz¹, Moritz Back¹, Carla Schaubhut¹, Sabina Wagner¹, Helena M B Seth-Smith^{2

3

4}, Patrick Scotton⁶, Maurice Redondo⁷, Christiane Beckmann⁷, Tanja Stadler⁸, Andrea Salzmann⁷, Henriette Kurth⁷, Karoline Leuzinger^{9

10}, Stefano Bassetti¹¹, Roland Bingisser¹², Martin Siegemund¹³, Maja Weisser¹⁴, Manuel Battegay¹⁴, Sarah Tschudin Sutter¹⁴, Aitana Lebrand⁴, Hans H Hirsch^{7

10

14}, Simon Fuchs¹, Adrian Egli^{2

3}

Affiliations

¹ Department of Health Basel-City, 4052 Basel, Switzerland.
² Applied Microbiology Research, Department of Biomedicine, University of Basel, 4056 Basel, Switzerland.
³ Division of Clinical Bacteriology and Mycology, University Hospital Basel, 4031 Basel, Switzerland.
⁴ SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland.
⁵ Department of Clinical Research, University Hospital Basel, 4031 Basel, Switzerland.
⁶ Corona Vaccination Centre for the Canton of Basel-City, 4058 Basel, Switzerland.
⁷ Viollier AG, 4123 Allschwil, Switzerland.
⁸ Department of Biosystems Science and Engineering, ETH Zurich, 4058 Basel, Switzerland.
⁹ Clinical Virology, University Hospital Basel, 4031 Basel, Switzerland.
¹⁰ Transplantation & Clinical Virology, Department of Biomedicine, University of Basel, 4056 Basel, Switzerland.
¹¹ Internal Medicine, University Hospital Basel, 4031 Basel, Switzerland.
¹² Emergency Medicine, University Hospital Basel, 4031 Basel, Switzerland.
¹³ Intensive Care Medicine, University Hospital Basel, 4031 Basel, Switzerland.
¹⁴ Infectious Diseases and Hospital Epidemiology, University Hospital Basel, University of Basel, 4031 Basel, Switzerland.

Abstract

(1) Background: Some COVID-19 vaccine recipients show breakthrough infection. It remains unknown, which factors contribute to risks and severe outcomes. Our aim was to identify risk factors for SCoV2 breakthrough infections in fully vaccinated individuals. (2) Methods: We conducted a retrospective case-control study from 28 December 2020 to 25 October 2021. Data of all patients with breakthrough infection was compared to data of all vaccine recipients in the Canton of Basel-City, Switzerland. Further, breakthrough infections by Alpha- and Delta-variants were compared. (3) Results: Only 0.39% (488/126,586) of all vaccine recipients suffered from a breakthrough infection during the observational period, whereof most cases were asymptomatic or mild (97.2%). Breakthrough infections after full vaccination occurred in the median after 78 days (IQR 47-123.5). Factors with lower odds for breakthrough infection were age (OR 0.987) and previous COVID-19 infection prior to vaccination (OR 0.296). Factors with higher odds for breakthrough infection included vaccination with Pfizer/BioNTech instead of Moderna (OR 1.459), chronic disease (OR 2.109), and healthcare workers (OR 1.404). (4) Conclusions: Breakthrough infections are rare and mild but can occur early after vaccination. This implies that booster vaccination might be initiated earlier, especially for risk groups. Due to new variants emerging repeatedly, continuous monitoring of breakthrough infections is crucial.

Keywords: Alpha; COVID-19; COVID-19 vaccine; Delta; Moderna; Pfizer/BioNTech; SARS-CoV-2; breakthrough infection.