A new study published in the Lancet Journal shows that the potential COVID-19 vaccine developed by AstraZeneca Plc and Oxford University enables a strong immune response in older adults. As a part of the study, healthy adults aged 18 years and older were enrolled at two UK clinical research facilities. This was done in an age escalation manner. People were divided into groups of 18–55 years, 56–69 years, and 70 years and older immunogenicity subgroups.
As the first step, participants were recruited to a low-dose cohort and all the age groups were randomly assigned to receive either intramuscular ChAdOx1 nCoV-19 (2·2â×â1010 virus particles) or a control vaccine, MenACWY. However, this was done using block randomisation. Certain ratios were also allotted. Late in October, after having security and safety of the trials reviewed by the US Food and Drug Administration, AstraZeneca resumed its major clinical trials for experimental COVID-19 vaccines. AstraZeneca had to pause the trials after the serious adverse reaction (SAE) was detected in volunteers. Also, AstraZeneca announced that the FDA regulators had approved resumption for the Oxford coronavirus vaccine in the US, UK, Brazil, South Africa, and Japan confirming that it was safe.
The main objective of the study was to assess the safety and cellular immunogenicity of a single-dose and two-dose schedule in adults older than 55 years. During the study, 560 participants were enrolled between May 30 and Aug 8, 2020. Out of this, 160 were aged 18–55 years, another 160 were aged 56–69 years and the remaining 240 were aged 70 years and older. The study said, “Seven participants did not receive the boost dose of their assigned two-dose regimen, one participant received the incorrect vaccine, and three were excluded from immunogenicity analyses due to incorrectly labelled samples. 280 (50%) of 552 analysable participants were female”.
It was then concluded that ChAdOx1 nCoV-19 works better in older adults than in younger adults. Also, the study suggests that it has similar immunogenicity across all the age groups. The study further said that ‘further assessment of the efficacy of this vaccine is warranted in all age groups and individuals with comorbidities’.