AstraZeneca’s experimental coronavirus vaccine appears to work safely in older people, generating as strong an immune response in those over the age of 70 as it does in younger people, British researchers reported Thursday.
The Phase 2 trial did not show whether the vaccine protected volunteers from infection, but it generated an immune response that would be expected to provide protection, the researchers reported in the Lancet medical journal.
AstraZeneca, which developed its vaccine with researchers at Britain’s Oxford University, is testing its vaccine in Phase 3 clinical trials around the world — the last stage before seeking regulatory approval.
The results: The Phase 2 results published Thursday involved 560 volunteers aged 18 and up; 240 of them over 70. That’s important, because older people are more likely to develop severe disease and to die from infection.
“Our findings show that the ChAdOx1 nCoV-19 vaccine was safe and well tolerated,” the researchers reported in the Lancet.
“If these responses correlate with protection in humans, these findings are encouraging because older individuals are at disproportionate risk of severe Covid-19 and so any vaccine adopted for use against SARS-CoV-2 must be effective in older adults.”
How does the vaccine work? ChAdOx1 is the vaccine’s experimental name. It’s made differently from the Pfizer and Moderna vaccines. It uses a modified cold virus called an adenovirus, but it’s one that infects chimpanzees and doesn’t make people sick. The virus is genetically engineered to carry a little piece of the coronavirus into the body and train the immune system to recognize and attack it.
The vaccines prompted the body to produce both antibodies and immune cells called T-cells. “The robust antibody and T-cell responses seen in older people in our study are encouraging. The populations at greatest risk of serious Covid-19 disease include people with existing health conditions and older adults,” Dr. Maheshi Ramasamy of the University of Oxford, who worked on the study, said in a statement.
Some context: The study comes after two Covid-19 vaccine candidates in the US reported 95% efficacy. Pfizer says it expects to seek emergency use authorization from the US Food and Drug Administration for its vaccine on Friday, and Moderna says it also plans to seek authorization soon.