AZ’s COVID-19 vaccine shows promise in young and old adults

AstraZeneca is on the up after announcing that its Oxford University-partnered COVID-19 vaccine candidate has shown promise in both older and younger adults.

According to a report from the Financial Times (FT), the vaccine candidate – AZD1222 – triggers protective antibodies and T cell responses in older age groups.

Since the beginning of the pandemic, older adults have been identified as having a higher risk of hospitalisation and death from COVID-19 compared to younger people.

According to the US Centers for Disease Control and prevention (CDC), it can also prove more challenging to find a vaccine that is effective for older adults.

This is because older adults have more risk factors associated with developing severe symptoms from infectious diseases, and also because the immune system undergoes immunosenescence as individuals age.

Immunosenescence is the gradual deterioration of the immune system, which occurs as a natural part of ageing. This makes it harder for vaccine developers to create a shot which prompts a similar immune response between young adults and older adults.

In addition to the promising immune response in older adults, AZ also said that adverse responses were lower among the elderly, according to Reuters.

“It is encouraging to see immunogenicity responses were similar between older and younger adults and that reactogenicity was lower in older adults, where the COVID-19 disease severity is higher,” an AZ spokesman also told Reuters.

The FT said that details of the findings are expected to be published in a clinical journal soon, although it did not specific which one.

Moderna, which is developing an mRNA-based vaccine for COVID-19, announced in August that its shot produced encouraging levels of neutralising antibodies and T cell responses in elderly participants.

The detailed results from the company’s phase 1 vaccine study were published in the New England Journal of Medicine in September.

Notably, these results demonstrated that the levels of neutralising antibodies observed in older participants were comparable to younger volunteers, and that only some older volunteers experienced transient adverse events including fever and fatigue after vaccination.

On Friday, AZ said that the US Food and Drug Administration (FDA) has authorised restarting its phase 3 COVID-19 vaccine trial.

The global clinical trial programme was paused in September after a participant in AZ’s UK-based study developed a serious adverse event.

The large-scale trial has now resumed in all global locations, including the US, UK, Brazil, South Africa and Japan.