3.3.2. 60+ Age Cohort
Immunogenicity assessment in the 60+ age cohort was performed on all 199 volunteers who received at least one dose of the vaccine. At the time of inclusion in the study, the proportion of volunteers seropositive in the NT was 65.5%. The results of immunogenicity assessment in the 60+ group are shown in Despite decreased immune status in elderly individuals due to the natural aging process, CoviVac vaccination led to high immunological efficacy in individuals in the 60+ age cohort. Then, 21 days after triple vaccination, the seroconversion rate (defined as a fourfold nAB titer increase) was 72.6% in all volunteers, 88.5% in volunteers who were seronegative at screening, and 65.5% in volunteers who were seropositive at screening, with GMT of 145.76, 31.13, and 291.22, respectively.In the same volunteers 21 days after the second dose of the vaccine, the seroconversion rate in seronegative individuals was 81.8%, while there was an insufficient immune response in volunteers who were seropositive at screening (29.2%) and in general in all volunteers regardless of baseline status (45.7%) with GMTs of 31.13, 291.22 and 86.6, respectively.Therefore, the most preferable immunization regimen for persons over 60 years of age who are at risk for morbidity and mortality from COVID-19 is triple vaccination with 21-day intervals, which showed higher immunological efficacy.