- An experimental coronavirus vaccine from partners AstraZeneca and the University of Oxford triggered immune responses in elderly participants in a clinical trial, according to data published Thursday in The Lancet.
- The results, which come from the Phase 2 portion of a combined multi-stage study in the U.K., found AstraZeneca's vaccine sparked similar responses in younger and older participants, but with fewer side effects reported in the elderly. A two-dose regimen of the vaccine led participants older than 70 years of age to produce infection-clearing T cells and antibodies that neutralize the coronavirus, suggesting — but not proving — the shot might help protect them from COVID-19.
- Older people are both more vulnerable to poor health outcomes from COVID-19 and less likely to respond to a vaccine because of weakened immune systems. An experimental coronavirus vaccine from BioNTech and Pfizer was recently shown in a large trial to protect elderly volunteers from COVID-19, however, raising expectations for others in development, including AstraZeneca and Oxford's shot, which could be the next to report results from a Phase 3 study.
The outlook for coronavirus vaccines has changed dramatically in the past two weeks.
When the Food and Drug Administration first outlined guidelines in June for a potential emergency vaccine approval, the agency set a 50% minimum bar for effectiveness against infection or disease. Such level of protection could make a significant impact on the public health impact of COVID-19, but would mean coronavirus vaccines look more like shots for influenza, which reduce the risk of illness by anywhere from 40% to 60% and are typically less effective in the elderly.
That, in turn, would leave a crucial need to fill. The Centers for Disease Control and Prevention estimates eight out of every 10 COVID-19 related deaths in the U.S. occur in patients over 65 years of age, making their protection particularly critical.
Initial Phase 3 data from Moderna as well as partners BioNTech and Pfizer, however, now indicate their coronavirus vaccines might be better than anticipated. Both reported results showing their shots to be roughly 95% effective at preventing COVID-19, a significant finding confirming that neutralizing antibodies offer some level of protection against disease.
Crucially, Pfizer said it's vaccine appeared just as effective in participants over 65. Moderna hasn't divulged the same level of detail yet, but the two vaccines are similar and both spurred immune responses in the elderly in earlier tests, with mostly mild to moderate side effects.
AstraZeneca and Oxford's vaccine is based on a different technology, one that uses a modified virus found in chimpanzees to deliver genetic instructions teching the body how to fight the coronavirus. The partners have yet to prove their vaccine can prevent COVID-19.
Multiple Phase 3 studies of the shot are ongoing in the U.S., U.K., Brazil and South Africa. But the vaccine targets the same characteristic spiky protein on the coronavirus, a similarity experts who have spoken with BioPharma Dive believe should lead to positive results.
AstraZeneca's most recent findings, which were published in The Lancet on Thursday, come from an early portion of a large Phase 2/3 placebo-controlled study in the U.K. that is evaluating the safety and immune responses of the vaccine in three age groups: 18 to 55 year olds, those 56-69, and volunteers older than 70. One hundred and twenty volunteers aged 56-69 and 200 who were 70 or older got the vaccine.
Investigators reported "similar safety and immunogenicity ... in older adults compared with younger adults" after two shots. The vaccine appeared to be more tolerable for older patients than younger ones. The most common side effects were mostly mild to moderate pain, tenderness, fatigue and fever, and were more frequently seen in younger participants.
An editorial published alongside the study noted a few limitations. There were few participants over 80 in the elderly group, and the study excluded those with "substantial chronic underlying illnesses and frailty." That's noteworthy, as waning immune responses to vaccination don't occur in all elderly patients and frailty, which "is increasingly understood" to be a factor when inoculation doesn't work, isn't specifically being tested against, wrote Melissa Andrew and Janet McElhaney of Dalhousie University in Halifax.
"A plan for how to consider frailty in COVID-19 vaccine development is important," they wrote.
AstraZeneca has said efficacy results from the U.K. trial, which is enrolling roughly 10,000 volunteers, could come by the end of the year. A larger study in the U.S. is underway as well, though data isn't expected until early 2021.
Studies of the AstraZeneca and Oxford shot were temporarily halted in September after a participant contracted an unexplained illness in the U.K. trial. Investigators couldn't link the case to the vaccine, however, and testing has since resumed. The Lancet paper indicated that details of "suspected unexpected serious adverse reactions" from the study "will be reported in detail in a subsequent publication."