A potential COVID-19 vaccine by AstraZeneca and Oxford University was well-tolerated among older adults and produced a strong immune response, according to data from a phase two clinical trial.
More than 99% of participants who received a boost dose of the vaccine had neutralizing antibody responses by two weeks, says the study, which was published Thursday in The Lancet journal.
The researchers found that the vaccine invoked a T-cell response that peaked at 14 days after vaccination, and antibody responses against the coronavirus spike protein “were boosted and maintained” at 28 days after booster vaccination for all age groups.
“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,” the researchers said in their study.
The trial included 560 participants ages 18 and older, of which 209 received a boost dose.
Of the 560 participants, 160 were 18 to 55 years old, 160 were 56 to 69 years old and 240 were 70 years and older. Younger participants appeared to experience local and systemic adverse reactions to the vaccines than older participants. For instance, after receiving two standard doses of the coronavirus vaccine, 88% of participants ages 18-55 years and 73% of participants ages 56-69 years experienced “vaccination local reactions.” Meanwhile, 61% of those 70 years and older experienced these reactions.
Thirteen serious adverse events occurred during the study period as of Oct. 26; however, none were linked to the study’s vaccine.
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