Research NoteReactogenicity among health care workers following a BNT162b2 or mRNA-1273 second dose after priming with a ChAdOx1 nCOV-19 vaccine
Introduction
On January 29, 2021, the European Medicines Agency approved vaccination against COVID-19 with the ChAdOx1 nCoV-19 vaccine (Vaxzevria, AstraZeneca) [1,2]. On March 19, 2021, French authorities recommended that administration of the ChAdOx1 nCoV-19 vaccine be ceased for people aged <55 years, owing to reports of rare thrombotic events, some of which were fatal [3]. Subsequently, it was recommended that the vaccination schedule be completed with administration of an mRNA vaccine 9 to 12 weeks after the primary dose [4].
A small number of studies have evaluated the short-term safety profile of ChAdOx1 nCoV-19 and mRNA heterologous vaccination [[5], [6], [7], [8]]. The results were variable, with some evidence of increased transient increased reactogenicity. The objective of this study was to describe and compare the reactogenicity of a second dose of an mRNA vaccine (BNT162b2 (Comirnaty, BNT-Pfizer) or mRNA-1273 (Spikevax, Moderna)) after priming with the ChAdOx1 nCoV-19 vaccine in health care workers (HCWs).
Section snippets
Methods
This single-centre prospective study recruited HCWs scheduled for COVID-19 vaccination. Voluntary participation in the study was offered to all HCWs who received a ChAdOx1 nCoV-19 vaccine between February 7, 2021 and March 19, 2021 at the vaccination centre of the university hospital of Caen, France. Participants were asked to provide information on their age, sex, work role, and e-mail address or personal phone number. No other information was collected for recruitment, and only an e-mail
Results
Over the study period, 1184 HCWs who had received a first dose of the ChAdOx1 nCoV-19 vaccine agreed to participate. The study population included 383 men (32.3 %), and the mean age was 35 years (standard deviation: 10.1). Participants included 154 doctors (13%), 284 nurses (24%), 118 caregivers (10%), 24 cleaners (2%), 332 health care students (28%), and 272 administrative staff (23%).
After the second dose, 356 of 1184 HCWs (30%) completed the online survey. The mean age was 36.6 years
Discussion
Our study provides new data on the side effect profile of the administration of a second dose of an mRNA vaccine after priming with a ChAdOx1 nCoV-19 vaccine in a cohort of 356 HCWs. Although 64.6% of 356 participants analyzed (n = 230) reported a systemic reaction and 55.6% (n = 141) presented with a grade 2 or 3 adverse event, only 11.5% (n = 41) reported being unable to work the day after vaccination, and 0.2% (n = 7) needed a medical consultation. Most side effects resolved within 3 days.
Transparency declaration
No conflicts of interest to declare.
Author contributions
AB and JM collected data. AB, JM, AF and RV analyzed data and drafted the report. All authors read and approved the final report.
Acknowledgements
The authors are grateful to all study participants at the University Hospital of Caen for their participation. The authors also thank Tanya Diefenbach-Elstob for correcting the manuscript and the entire staff of the vaccination centre of the University Hospital of Caen for their support of the study.
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