PremiumGetting the second shot of Pfizer COVID-19 vaccine after 12 weeks increases antibody response in older people by three-and-a-half times compared to those who receive it at a three-week interval, as per a study conducted in UK. The study was conducted on 175 people aged over 80 who are given the second Pfizer vaccine dose at a three-week interval and those at a 12-week interval. The Pfizer vaccine was originally authorised for a three-week interval between doses.
The report comes a few days UK government reduced the gap between the two doses of COVID-19 vaccines to eight weeks. Meanwhile, India extended the interval between two doses of the Covishield preventive to 12-16 weeks. Earlier it was suggested that the second jab be taken within maximum of eight weeks after getting the first dose.
Here what the study suggested
The yet-to-be peer-reviewed 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. The team concluded that extending administration of the second Pfizer vaccine to 12 weeks potentially enhances and extends antibody immunity.
"SARS-CoV-2 vaccines have been remarkably effective in providing large-scale protection against infection and symptomatic disease - but many questions remain regarding their optimal delivery for provision of effective and sustained immunity," said study first author Helen Parry, from the University of Birmingham, UK.
"The study is crucial, particularly in older people, as immune responses to vaccination deteriorate with age," said Parry.
Understanding how to optimise COVID-19 vaccine schedules and maximise immune responses within this age group is vitally important, the resaercher said.
“The enhanced antibody responses seen after an extended interval may help to sustain immunity against COVID-19 over the longer term and further improve the clinical efficacy of this powerful vaccine platform," said corresponding author of the study Paul Moss, from the University of Birmingham.
“Our research findings may be important in the development of global vaccination strategy as extension of interval of the second vaccine dose in older people may potentially reduce the need for subsequent booster vaccines," Moss said.
The research saw the team taking blood samples for analysis in the lab after participants’ first vaccine and then again two to three weeks after participants had received their second vaccine.
Several countries chose to expand the gap
The UK and several other countries have already chosen to expand gap to a 12-week so that higher percentage of the population receive the first dose faster. However, the UK last week cut the gap to eight weeks in view of the spread of the B.1.617 variant that originated in India.
(With inputs from agencies)
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