Analysis of Neutralization Titers against SARS-CoV-2 in Health-Care Workers Vaccinated with Prime-Boost mRNA–mRNA or Vector–mRNA COVID-19 Vaccines

Christina Sølund, Alexander P. Underwood, Carlota Fernandez-Antunez, Signe Bollerup, Lotte S. Mikkelsen, Signe Lysemose Villadsen, Ulrik Fahnøe, Anni Assing Winckelmann, Shan Feng, Caroline A. Nørløv Vinten, Magnus Illum Dalegaard, Greta Vizgirda, Anna Louise Sørensen, Santseharay Ramirez, Jens Bukh, Nina Weis*

*Corresponding author for this work

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Abstract

With increasing numbers of vaccine-breakthrough infections worldwide, assessing the immunogenicity of vaccinated health-care workers that are frequently exposed to SARS-CoV-2-infected individuals is important. In this study, neutralization titers against SARS-CoV-2 were assessed one month after completed prime-boost vaccine regimens in health-care workers vaccinated with either mRNA–mRNA (Comirnaty®, BioNTech-Pfzier, Mainz, Germany/New York, NY, USA, n = 98) or vector-based (Vaxzevria®, Oxford-AstraZeneca, Cambridge, UK) followed by mRNA-based (Comirnaty® or Spikevax®, Moderna, Cambridge, MA, USA) vaccines (n = 16). Vaccine-induced neutralization titers were compared to time-matched, unvaccinated individuals that were infected with SARS-CoV-2 and presented with mild symptoms (n = 38). Significantly higher neutralizing titers were found in both the mRNA–mRNA (ID50: 2525, IQR: 1667–4313) and vector–mRNA (ID50: 4978, IQR: 3364–7508) prime-boost vaccine regimens when compared to SARS-CoV-2 infection (ID50: 401, IQR: 271–792) (p < 0.0001). However, infection with SARS-CoV-2 induced higher titers when compared to a single dose of Vaxzevria® (p = 0.0072). Between mRNA–mRNA and vector– mRNA prime-boost regimens, the vector–mRNA vaccine regimen induced higher neutralization titers (p = 0.0054). Demographically, both age and time between vaccination doses were associated with vaccine-induced neutralization titers (p = 0.02 and p = 0.03, respectively). This warrants further investigation into the optimal time to administer booster vaccination for optimized induction of neutralizing responses. Although anecdotal (n = 3), those with exposure to SARS-CoV-2, either before or after vaccination, demonstrated superior neutralizing titers, which is suggestive of further boosting through viral exposure.

Original languageEnglish
Article number75
JournalVaccines
Volume10
Issue number1
ISSN2076-393X
DOIs
Publication statusPublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • COVID-19
  • MRNA vaccine
  • Neutralization/neutralisation
  • Neutralizing/neutralising antibodies
  • SARS-CoV-2
  • Vector vaccine

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