Immune responses following the first dose of the Sputnik V (Gam-COVID-Vac)
Chandima Jeewandara, Suranga Fernando, Pradeep Darshana Pushpakumara, Shyrar Tanussiya Ramu, Achala Kamaladasa, Banuri Gunasekara, Inoka Sepali Aberathna, Heshan Kuruppu, Thushali Ranasinghe, Shashika Dayarathne, Osanda Dissanayake, Nayanathara Gamalath, Dinithi Ekanayake, Jewantha Jayamali, Ayesha Wijesinghe, Madushika Dissanayake, Gayasha Somathilake, Michael Harvie, Saubhagya Danasekara, Deshni Jayathilaka, Helanka Wijayatilake, Nihal Weerasooriya, Chinthaka Kekulandara, Lisa Schimanski, Pramila Rijal, Tiong Kit Tan, Tao Dong, Alain Townsend, Graham S. Ogg, Gathsaurie Neelika Malavige
Abstract
As the first dose of Gam-COVID-Vac, is currently used as a single dose vaccine in some countries, we investigated the immunogenicity of this at 4 weeks (327 naïve individuals). 88.7% seroconverted, with significantly lower seroconversion rates in those over 60 years (p = 0.004) and significantly lower than previously seen with AZD1222 (p = 0.018). 82.6% developed ACE2 receptor blocking antibodies, although levels were significantly lower than following natural infection (p = 0.0009) and a single dose of AZD1222 (p < 0.0001). Similar titres of antibodies were observed to the receptor binding domain of WT, B.1.1.7 and B.1.617.2 compared to AZD1222, while the levels for B.1.351 were significantly higher (p = 0.006) for Gam-COVID-Vac. 30% developed ex vivo IFNγ ELISpot responses (significantly lower than AZD1222), and high frequency of CD107a expressing T cells along with memory B cell responses. Although single dose of Gam-COVID-Vac was highly immunogenic, administration of a second dose is likely to be beneficial.