Researchers analyzed blood samples for 175 people older than 80. Ninety-nine participants received their second Pfizer shot three weeks after their first, while 73 got their second shot 12 weeks after their first. Fifteen participants (10 in the three-week group and five in the 12-week group) who had prior COVID-19 infections were excluded from the analysis, as prior infection can play a major part in the immune response generated after vaccination.
The study found participants who received their second dose 12 weeks after their first produced a peak antibody response 3.5 times higher than participants who received their second dose 3 weeks after the first.
“This research is crucial, particularly in older people, as immune responses to vaccination deteriorate with age,” Helen Parry, MD, the study’s lead author, said in a news release. “Understanding how to optimise COVID-19 vaccine schedules and maximise immune responses within this age group is vitally important.”
