The Oxford vaccine team separated vaccinated people into groups of 18–55 years (160 participants), 56–69 years (160), and 70 years and older (240). Some received the candidate coronavirus vaccine and some a control meningitis vaccine at one or two doses each, to measure if booster vaccination would help. Their new study, published in The Lancet, investigated whether older adults can develop coronavirus-specific immune responses similar to younger adults.
Not only did the older adults develop similar immune responses to younger people, they also tolerated the vaccine better with fewer reports of side-effects, such as fatigue and muscle ache. Neutralising antibodies that block infection and virus-specific T cells are thought to be important for protective immunity, and older adults in the Oxford trial showed evidence of both. Those who received a booster vaccination had even better responses.
Other coronavirus vaccines in older people
Other studies with vaccine preparations similar to the Oxford group, where the vaccine is delivered by a harmless adenovirus, have reported early results in older people. A single dose adenovirus-based vaccine (CanSino Biological/Beijing Institute of Biotechnology) raised a robust immune response – but less so in those older than 55 years. The two-dose Russian Sputnik V adenovirus vaccine – which also recently reported results in The Lancet – showed consistent responses in under 60s.
Two vaccines using inactivated coronavirus were also able to elicit antibody responses. The Wuhan Institute Biological Products/SinoPharm study showed that volunteers under 59-years-old generated neutralising antibodies, and the Beijing Institute Biological products/SinoPharm study measured robust antibodies but showed lower responses in the over 60s.
A different vaccine approach involves the use of mRNA, messenger molecules that enter our cells and kick off the production of coronavirus proteins to stimulate our immune system. Two mRNA-based vaccines with two-dose protocols were tested under-55s and over-65s with positive results. The Pfizer/BioNTech vaccine was the first concluded trial with 95 per cent final efficacy, and they estimated the efficacy for over 65s at an impressive 94%.
Moderna also has released exciting interim efficacy data and previously reported potent neutralising responses in both under 55s and those over 56.
Early results from ongoing trials show that we are able to design vaccines that elicit potent coronavirus responses in people over 60. Vaccine efficacy will vary with different vaccine preparations, and we need to choose carefully which formulations will work best in older people, which doses are most effective and when to administer booster vaccinations to achieve the best results.
It has been less than a year since the new coronavirus jumped to humans, and we are entering the privileged position of being able to choose between different vaccines.
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