Real-world data shows increased reactogenicity in adults after heterologous compared to homologous prime-boost COVID-19 vaccination, March-June 2021, England

Euro Surveill. 2021 Jul;26(28):2100634. doi: 10.2807/1560-7917.ES.2021.26.28.2100634.


Adults receiving heterologous COVID-19 immunisation with mRNA (Comirnaty) or adenoviral-vector (Vaxzevria) vaccines had higher reactogenicity rates and sought medical attention more often after two doses than homologous schedules. Reactogenicity was higher among ≤ 50 than > 50 year-olds, women and those with prior symptomatic/confirmed COVID-19. Adults receiving heterologous schedules on clinical advice after severe first-dose reactions had lower reactogenicity after dose 2 following Vaxzevria/Comirnaty (93.4%; 95% confidence interval: 90.5-98.1 vs 48% (41.0-57.7) but not Comirnaty/Vaxzevria (91.7%; (77.5-98.2 vs 75.0% (57.8-87.9).

Keywords: BNT162b2; COVID-19 vaccine; ChAdOx1/nCoV-19; Comirnaty; Reactogenicity; Vaxevria; heterologous schedule; prime-boost.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • COVID-19 Vaccines*
  • COVID-19*
  • England / epidemiology
  • Female
  • Humans
  • SARS-CoV-2
  • Vaccination


  • COVID-19 Vaccines