Research Note
Reactogenicity among health care workers following a BNT162b2 or mRNA-1273 second dose after priming with a ChAdOx1 nCOV-19 vaccine

https://doi.org/10.1016/j.cmi.2022.02.010Get rights and content

Abstract

Objectives

In March 2021, French authorities recommended a heterologous second dose of the mRNA vaccine for persons aged <55 years, with administration 9 to 12 weeks after the first dose of ChAdOx1 nCoV-19. This recommendation was despite a lack of data on the reactogenicity and safety of the regimen. Since then, several studies have shown an acceptable short-term safety profile of ChAdOx1 nCoV-19 and BNT162b2 heterologous vaccination, although some transient increased reactogenicity has been described.

Methods

We performed a single-centre prospective observational cohort study among health care workers (HCWs) at a tertiary care hospital to assess the reactogenicity of the BNT162b2 and mRNA-1273 vaccines administered as a second dose in participants primed with ChAdOx1 nCoV-19.

Results

Among 1184 HCWs, 356 (30%) agreed to participate. Of the participants, 32.3% were male, and the mean age was 35 years (standard deviation: 10.1 years). Of the participants, 229 received BNT162b2 and 127 received mRNA-1273. A systemic reaction was observed in 130 of 229 (56.8%) and 100 of 127 (78.7%) HCWs, respectively. Injection site reactions were generally limited (grade 1 or 2 in 163 of 229 (97.6%) and 90 of 127 (85.7 %) HCWs, respectively). After adjustment for age, sex, and HCW role, receiving the mRNA-1273 vaccine was associated with higher reactogenicity with more grade 3 side effects (adjusted OR (aOR): 3.34; 95% CI, 1.91–5.85), more systemic symptoms (aOR: 2.82; 95% CI, 1.69–4.7), and not being able to work (aOR: 8.35; 95% CI, 3.78–18.44) compared with receiving the BNT162b2 vaccine.

Discussion

Among patients receiving the mRNA1273 vaccine as a second dose, our study confirms good tolerance of the heterologous schedule with a higher risk of short-term side effects in comparison with patients receiving the BNT162b2 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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