AstraZeneca’s (AZ) COVID-19 vaccine candidate AZD1222/ChAdOx1 nCoV-19 has produced some promising results in elderly trial participants, new data published in The Lancet today shows.
The phase 2 study of the vaccine, developed by Oxford University researchers, included 560 healthy adult volunteers, 160 of which were aged 56-69 and 240 were aged 70 years and older.
The new findings show that the vaccine was safe and well tolerated in older and younger adults, with a similar immune response reported across the age groups following a boost vaccination.
The vaccine also induced a specific antibody response to the SARS-CoV-2 spike protein at 28 days after a single dose across all age groups.
Similar patterns were observed with regards to neutralising antibody response with no notable difference at day 28 after the first vaccine dose regardless of age or vaccine dose. In participants who received a second dose of the vaccine, a booster effect was observed, however.
“Here we found similar safety and immunogenicity of ChAdOx1 nCoV-19 in older adults compared with younger adults, which could support the use of this vaccine in this older age group, if it is shown to be protective in phase 3 trials,” commented the researchers.
Previously, experts have raised concerns that a potential vaccine against COVID-19 may not be as effective in the older population, as the elderly are likely to have a weaker immune system compared to younger people.
A number of studies have shown that a decreasing immune function caused by ageing results in a decreased immune response to vaccines, with this response previously observed for vaccines for influenza and hepatitis B.
AZ is currently investigating whether the vaccine candidate can prevent COVID-19 in a global phase 3 clinical trial programme, with studies currently ongoing in the UK, the US and Brazil.
The UK government has already signed a supply deal with AZ for 100 million doses of its potential COVID-19 vaccine, which is dependent on whether the vaccine continues to prove effective in upcoming trial readouts.
The UK has also secured doses of Pfizer/BioNTech’s COVID-19 vaccine, as well as potential vaccines from Valneva, Sanofi/GlaxoSmithKline, Moderna, Novavax and Johnson & Johnson.
“The government has signed agreements with seven vaccine developers to secure the most promising vaccines for the UK. The government’s Vaccine Taskforce is pursuing a portfolio approach to obtaining vaccines for the UK across different vaccine formats, to maximise the chances of finding safe and effective vaccines,” said Kate Bingham, chair of the government’s Vaccine Taskforce.
“We will continue to monitor the field of promising vaccines, and are very encouraged by the effectiveness shown by these early frontrunners, but we must remain vigilant to the fact that no vaccine is yet approved for use by regulators,” she added.