Oxford COVID-19 vaccine in older adults safe, provokes immune response

The University of Oxford novel coronavirus (COVID-19) vaccine showed similar safety and immunogenicity results in healthy older adults to those seen in younger adults, according to early stage results published in The Lancet.

The new trial included 560 participants, 160 of which were 18-55 years old, 160 of which were 56-69 years old, and 240 of which were 70 years and older. The participants were split were split into 10 groups where they received either the ChAdOx1 nCoV-19 vaccine at a low or standard dose, or a control vaccine, the meningococcal conjugate vaccine. Participants over 55 years old were also split into groups and either given a single dose of vaccine, or two doses 28 days apart.

Following vaccination, participants were observed for a minimum of 15 minutes in case of any immediate adverse events, and participants recorded any adverse events for seven days afterwards. Participants will continue to be monitored for any serious adverse events for one year following final vaccination. The yearlong data are not yet available, the researchers said.

The phase 2 trial found that the vaccine causes few side effects, and induces immune responses in both parts of the immune system in all age groups and at low and standard dose, provoking a T cell response within 14 days of the first dose of vaccination and an antibody response within 28 days of the booster dose of vaccination, according to the study.

Phase 3 trials are ongoing to confirm these results, as well as how effective the vaccine is in protecting against infection with SARS-CoV-2, the virus that causes COVID-19, in a broader range of people, including older adults with underlying health conditions.

The new study is the fifth published clinical trial of a vaccine against SARS-CoV-2 tested in an older adult population. Other COVID-19 vaccines have also been shown to generate immune responses in older adults, but it can be difficult to compare results between different studies. One study has shown similar immune responses in young and old adults, the Moderna mRNA vaccine, while other trials have suggested lower measured responses in older adults, compared to younger adults receiving the same vaccine, including the CanSino Biologics single dose adenovirus-vector vaccine, Pfizer and BioNTech mRNA vaccine, and SinoPharm and Beijing Institute of Biological Products inactivated viral vaccine, the researchers said.

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