Jeewandara C., Aberathna IS., Gomes L., Pushpakumara PD., Danasekara S., Guruge D., Ranasinghe T., Gunasekera B., Kamaladasa A., Kuruppu H., Somathilake G., Dissanayake O., Gamalath N., Ekanayake D., Jayamali J., Jayathilaka D., Mudunkotuwa A., Harvie M., Nimasha T., Wijayamuni R., Schimanski L., Rijal P., Tan TK., Dong T., Townsend A., Ogg GS., Malavige GN.

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

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

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