Immunogenicity and protective efficacy of one- and two-dose regimens of the Ad26.COV2.S COVID-19 vaccine candidate in adult and aged rhesus macaques

  1. Laura Solforosi
  2. Harmjan Kuipers
  3. Sietske K. Rosendahl Huber
  4. Joan E.M. van der Lubbe
  5. Liesbeth Dekking
  6. Dominika N. Czapska-Casey
  7. Ana Izquierdo Gil
  8. Miranda R.M. Baert
  9. Joke Drijver
  10. Joost Vaneman
  11. Ella van Huizen
  12. Ying Choi
  13. Jessica Vreugdenhil
  14. Sanne Kroos
  15. Adriaan H. de Wilde
  16. Eleni Kourkouta
  17. Jerome Custers
  18. Tim J. Dalebout
  19. Sebenzile K. Myeni
  20. Marjolein Kikkert
  21. Eric J. Snijder
  22. Dan H. Barouch
  23. Kinga P. Böszörményi
  24. Marieke A. Stammes
  25. Ivanela Kondova
  26. Ernst J. Verschoor
  27. Babs E. Verstrepen
  28. Gerrit Koopman
  29. Petra Mooij
  30. Willy M.J.M. Bogers
  31. Marjolein van Heerden
  32. Leacky Muchene
  33. Jeroen T.B.M. Tolboom
  34. Ramon Roozendaal
  35. Hanneke Schuitemaker
  36. Frank Wegmann
  37. Roland C. Zahn
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Abstract

Safe and effective coronavirus disease (COVID)-19 vaccines are urgently needed to control the ongoing pandemic. While single-dose vaccine regimens would provide multiple advantages, two doses may improve the magnitude and durability of immunity and protective efficacy. We assessed one- and two-dose regimens of the Ad26.COV2.S vaccine candidate in adult and aged non-human primates (NHP). A two-dose Ad26.COV2.S regimen induced higher peak binding and neutralizing antibody responses compared to a single dose. In one-dose regimens neutralizing antibody responses were stable for at least 14 weeks, providing an early indication of durability. Ad26.COV2.S induced humoral immunity and Th1 skewed cellular responses in aged NHP that were comparable to adult animals. Importantly, aged Ad26.COV2.S-vaccinated animals challenged 3 months post -dose 1 with a SARS-CoV-2 spike G614 variant showed near complete lower and substantial upper respiratory tract protection for both regimens. These are the first NHP data showing COVID-19 vaccine protection against the SARS-CoV-2 spike G614 variant and support ongoing clinical Ad26.COV2.S development.

Summary

COVID-19 vaccines are urgently needed and while single-dose vaccines are preferred, two-dose regimens may improve efficacy. We show improved Ad26.COV2.S immunogenicity in non-human primates after a second vaccine dose, while both regimens protected aged animals against SARS-CoV-2 disease.

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