Delay in giving second jabs of Pfizer vaccine improves immunity

Study finds antibodies against Sars-CoV-2 three-and-a-half times higher in people vaccinated again after 12 weeks rather than three

The UK’s decision to delay second doses of coronavirus vaccines has received fresh support from research on the over-80s which found that giving the Pfizer/BioNTech booster after 12 weeks rather than three produced a much stronger antibody response.

A study led by the University of Birmingham in collaboration with Public Health England found that antibodies against the virus were three-and-a-half times higher in those who had the second shot after 12 weeks compared with those who had it after a three-week interval.

Most people who have both shots of the vaccine will be well protected regardless of the timing, but the stronger response from the extra delay might prolong protection because antibody levels naturally wane over time.

Dr Helen Parry, a senior author on the study at Birmingham, said: “We’ve shown that peak antibody responses after the second Pfizer vaccination are really strongly boosted in older people when this is delayed to 11 to 12 weeks. There is a marked difference between these two schedules in terms of antibody responses we see.”

In the first weeks of the vaccine programme the UK took the bold decision to delay administering booster shots so that more elderly and vulnerable people could more quickly receive their first shots.

The move was controversial because medicines regulators approved both the Pfizer/BioNTech and Oxford/AstraZeneca vaccines on the basis of clinical trials that spaced out the doses by only three or four weeks.

Researchers from Oxford University showed in February that antibody responses were more than twice as strong when boosters of their vaccine were delayed for 12 weeks. But the latest study is the first to compare immune responses after different timings with the Pfizer/BioNTech jab.

The scientists analysed blood samples from 175 over-80s after their first vaccine and again two to three weeks after the booster. Among the participants 99 had the second shot after three weeks, while 73 waited 12 weeks. After the second dose, all had antibodies against the virus’s spike protein, but the level was 3.5 times higher in the 12-week group.

The researchers then looked at another arm of the immune system, the T cells that destroy infected cells. They found that T cell responses were weaker when the booster was delayed, but settled down to similar levels when people were tested more than three months after the first shot. Details are published in pre-print form and have yet to be peer reviewed.

“This study further supports the growing body of evidence that the approach taken in the UK of delaying that second dose has really paid off,” said Dr Gayatri Amirthalingam, consultant epidemiologist at Public Health England.

“Individuals need to really complete their second dose when it’s offered to them because it not only provides additional protection but potentially longer lasting protection against Covid-19.”

The findings come as new data from Public Health England suggested that the vaccination programme had prevented 11,700 deaths by the end of April 2021 in those aged 60 and over, and at least 33,000 hospitalisations in those aged 65 and over in the same period.

“Overall, these data add considerable support to the policy of delaying the second dose of Covid-19 vaccine when vaccine availability is limited and the at-risk population is large,” said Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh.

“Longer term follow-up of this cohort will help us to understand which vaccine interval will be optimal in the future, once the immediate crisis is over.”


Ian Sample Science editor

The GuardianTramp

Related Content

Article image
Vaccine experts defend UK decision to delay second Pfizer Covid jab
Medics told they risk undermining public confidence by querying policy of three-month gap between doses

Michael Savage, Robin McKie and James Tapper

23, Jan, 2021 @10:30 PM

Article image
Moderna, Pfizer or AstraZeneca? The ridiculous, diverting rise of vaccine envy
Casual vaccine chat is today’s only form of small talk, so it’s not surprising it would take a lightheartedly tribal turn. Ultimately, of course, gratitude is at the heart of the conversation

Zoe Williams

21, Jun, 2021 @6:00 AM

Article image
How does the Pfizer/BioNTech vaccine work and who will get it?
Covid vaccine with an efficacy of almost 95% has been authorised by the UK medicines regulator

Nicola Davis Science correspondent

02, Dec, 2020 @7:16 AM

Article image
6 key questions about the Pfizer/BioNTech Covid-19 vaccine
There are grounds for optimism but also several unknowns around this coronavirus vaccine

Natalie Grover Science correspondent

10, Nov, 2020 @3:58 PM

Article image
UK orders extra Covid vaccines for autumn 2022 booster campaign
Pfizer reportedly asked to supply 35m more doses, with final go-ahead for this year’s programme still awaited

Andrew Sparrow Political correspondent

11, Aug, 2021 @9:51 AM

Article image
One Pfizer/BioNTech jab gives '90% immunity' from Covid after 21 days
New analysis runs counter to earlier study which suggested one dose may not give adequate protection

Sarah Boseley

03, Feb, 2021 @9:11 PM

Article image
Vaccine experts call for clarity on UK's 12-week Covid jab interval
British Society for Immunology calls for a robust programme monitoring the body’s immune response

Nicola Davis Science correspondent

24, Jan, 2021 @2:51 PM

Article image
From Pfizer to Moderna: who's making billions from Covid-19 vaccines?
The companies in line for the biggest windfalls – and the shareholders who have already made fortunes

Julia Kollewe

06, Mar, 2021 @11:55 AM

Article image
The Guardian view on coronavirus and vaccine scepticism: time to act | Editorial
Editorial: Plans for mass immunisation against Covid-19 are developing fast, but concerns must be addressed


22, Nov, 2020 @6:30 PM

Article image
It's the 'vaccine hesitant', not anti-vaxxers, who are troubling public health experts | Gaby Hinsliff
To make vaccination work, we must reach out to the naturally cautious, says Guardian columnist Gaby Hinsliff

Gaby Hinsliff

16, Nov, 2020 @12:00 PM