Early T cell and binding antibody responses are associated with COVID-19 RNA vaccine efficacy onset
Shirin Kalimuddin, C Tham, Martin Qui, Ruklanthi de Alwis, Jean Xiang Ying Sim, Joey Ming Er Lim, Hwee-Cheng Tan, Ayesa Syenina, Summer L. Zhang, Nina Le Bert, Anthony T. Tan, Yan Shan Leong, Jia Xin Yee, Eugenia Z. Ong, Eng Eong Ooi, Antonio Bertoletti, Jenny G. Low
Abstract
BACKGROUND: RNA vaccines against coronavirus disease 2019 (COVID-19) have demonstrated ∼95% efficacy in phase III clinical trials. Although complete vaccination consisted of 2 doses, the onset of protection for both licensed RNA vaccines was observed as early as 12 days after a single dose. The adaptive immune response that coincides with this onset of protection could represent the necessary elements of immunity against COVID-19. METHODS: Serological and T cell analysis was performed in a cohort of 20 healthcare workers after receiving the first dose of the Pfizer/BioNTech BNT162b2 vaccine. The primary endpoint was the adaptive immune responses detectable at days 7 and 10 after dosing. FINDINGS: Spike-specific T cells and binding antibodies were detectable 10 days after the first dose of the vaccine, in contrast to receptor-blocking and severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) neutralizing antibodies, which were mostly undetectable at this early time point. CONCLUSIONS: Our findings suggest that early T cell and binding antibody responses, rather than either receptor-blocking or virus neutralizing activity, induced early protection against COVID-19. FUNDING: The study was funded by a generous donation from The Hour Glass to support COVID-19 research.