In a new study from the University of Birmingham, researchers found that antibody response in older people is three-and-a-half times greater in those who have the second dose of the Pfizer COVID-19 vaccine after 12 weeks compared to those who have it at a three-week interval.
The team examined 175 people who were aged over 80 and living independently.
They compared the immune response between those who are given the second Pfizer vaccine at a three-week interval and those at a 12-week interval.
The Pfizer vaccine was originally authorized for a three-week interval between doses; however several countries, including the UK, chose to expand this to a 12-week interval to allow a higher percentage of the population to receive one vaccine dose quicker.
The research found that extending the second dose interval to 12 weeks increased the peak SARS-CoV-2 spike specific antibody response 3.5-fold compared to those who had the second vaccine at three weeks.
Although the peak cellular immune responses were lower after the delayed second vaccine, responses were comparable between the groups when measured at a similar time point following the first dose.
The team concluded that extending the administration of the second Pfizer vaccine to 12 weeks potentially enhances and extends antibody immunity, which is believed to be important in virus neutralization and prevention of infection.
They say this research is crucial, particularly in older people, as immune responses to vaccination deteriorate with age.
Understanding how to optimize COVID-19 vaccine schedules and maximize immune responses within this age group is vitally important.
The study was published as a preprint. One author of the study is Dr. Helen Parry.
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