Safety and immunogenicity of ChAdOx1 nCoV-19 vaccine administered in a prime-boost regimen in young and old adults (COV002): a single-blind, randomised, controlled, phase 2/3 trial
RCT (n=560) found antibody responses against SARS-CoV-2 spike protein were induced in all age groups and were boosted and maintained at 28 days after booster vaccination, including in ≥70 years group. Cellular immune responses were also induced in all age and dose groups.
Source:
The Lancet
SPS commentary:
According to a commentary, the main study limitations were its single-blind design, the inclusion of few participants older than 80 years, and exclusion of people with substantial underlying chronic illnesses and frailty. It looks at how the results might be applied to the true target populations for COVID-19 vaccines. It notes that the current UK Joint Committee on Vaccination and Immunisation top priority groups are: older adults living in care homes and care home workers, all those aged 80 years and older, and health-care and social-care workers, and all those aged 75 years and older. It discusses frailty and the concept of immunosenescence (waning of immune responses), which is important for understanding vaccine responses in older adults, noting that there is increasing evidence that immunosenescence is not universally or evenly experienced with biological ageing but is part of what contributes to the variability in susceptibility that is seen with frailty and an increasing burden of health conditions.