Immune responses following the first dose of the Sputnik V (Gam-COVID-Vac).
Jeewandara C., Fernando S., Pushpakumara PD., Ramu ST., Kamaladasa A., Gunasekara B., Aberathna IS., Kuruppu H., Ranasinghe T., Dayarathne S., Dissanayake O., Gamalath N., Ekanayake D., Jayamali J., Wijesinghe A., Dissanayake M., Somathilake G., Harvie M., Danasekara S., Jayathilaka D., Wijayatilake HDK., Weerasooriya N., Kekulandara C., Schimanski L., Rijal P., Tan TK., Dong T., Townsend A., Ogg GS., Malavige GN.
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.