Immunity, Inflammation and Disease (Apr 2022)

Kinetics of immune responses to the AZD1222/Covishield vaccine with varying dose intervals in Sri Lankan individuals

  • Chandima Jeewandara,
  • Inoka Sepali Aberathna,
  • Laksiri Gomes,
  • Pradeep Darshana Pushpakumara,
  • Saubhagya Danasekara,
  • Dinuka Guruge,
  • Thushali Ranasinghe,
  • Banuri Gunasekera,
  • Achala Kamaladasa,
  • Heshan Kuruppu,
  • Gayasha Somathilake,
  • Osanda Dissanayake,
  • Nayanathara Gamalath,
  • Dinithi Ekanayake,
  • Jeewantha Jayamali,
  • Deshni Jayathilaka,
  • Anushika Mudunkotuwa,
  • Michael Harvie,
  • Thashmi Nimasha,
  • Ruwan Wijayamuni,
  • Lisa Schimanski,
  • Pramila Rijal,
  • Tiong K. Tan,
  • Tao Dong,
  • Alain Townsend,
  • Graham S. Ogg,
  • Gathsaurie Neelika Malavige

DOI
https://doi.org/10.1002/iid3.592
Journal volume & issue
Vol. 10, no. 4
pp. n/a – n/a

Abstract

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Abstract Background To understand the kinetics of immune responses with different dosing gaps of the AZD1222 vaccine, we compared antibody and T cell responses in two cohorts with two different dosing gaps. Methods Antibodies to the SARS‐CoV‐2 virus were assessed in 297 individuals with a dosing gap of 12 weeks, sampled 12 weeks post second dose (cohort 1) and in 77 individuals with a median dosing gap of 21.4 weeks (cohort 2) sampled 6 weeks post second dose. ACE2‐blocking antibodies (ACE2‐blocking Abs), antibodies to the receptor‐binding domain (RBD) of variants of concern (VOC), and ex vivo T cell responses were assessed in a subcohort. Results All individuals (100%) had SARS‐CoV‐2‐specific total antibodies and 94.2% of cohort 1 and 97.1% of cohort 2 had ACE2‐blocking Abs. There was no difference in antibody titers or positivity rates in different age groups in both cohorts. The ACE2‐blocking Abs (p < .0001) and antibodies to the RBD of the VOCs were significantly higher in cohort 2 compared to cohort 1. 41.2% to 65.8% of different age groups gave a positive response by the hemagglutination assay to the RBD of the ancestral virus and VOCs in cohort 1, while 53.6%–90% gave a positive response in cohort 2. 17/57 (29.8%) of cohort 1 and 17/29 (58.6%) of cohort 2 had ex vivo interferon (IFN)γ ELISpot responses above the positive threshold. The ACE2‐blocking antibodies (Spearman's r = .46, p = .008) and ex vivo IFNγ responses (Spearman's r = .71, p < .0001) at 12 weeks post first dose, significantly correlated with levels 12 weeks post second dose. Conclusions Both dosing schedules resulted in high antibody and T cell responses post vaccination, although those with a longer dosing gap had a higher magnitude of responses, possibly as immune responses were measured 6 weeks post second dose compared to 12 weeks post second dose.

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