96% of Britons develop Covid antibodies after one dose of vaccine

More than 96% of Britons develop Covid antibodies after one dose of the Pfizer or AstraZeneca vaccine, ‘remarkable’ real-world data shows

  • Study of 8,517 people shows 99% of people have antibodies after two doses
  • UCL research shows older people are less protected after a first vaccine dose
  • AstraZeneca and Pfizer jabs produced the same antibody levels after four weeks 

More than 96 per cent of Britons develop Covid antibodies after one Pfizer or AstraZeneca vaccine, real world data suggests.

A study of 8,517 people in England and Wales found 96.42 per cent of adults developed the virus-fighting proteins 28 to 34 days after their first dose.

It rose to more than 99 per cent seven to 14 days after a second dose of either jab, the University College London (UCL) research found.

The real world study looked at 13,232 antibody samples from people with an average of 65, to reflect the older age groups first given a vaccine.

The fact every participant had antibodies suggests they had some immunity to the virus, but the proteins are only one part of the immune response to Covid.

Antibody rates rose slightly more quickly in people who had the Pfizer than the AstraZeneca jab, though both levelled out after four weeks.  

It comes as Brits were told making the decision to take their vaccine today could ensure the June 21 date for the final stage of lockdown easing is met.

There are fears that the highly infectious Indian variant could cause an uptick in hospitalisations and deaths because almost 30million people are still unvaccinated.

SAGE adviser Steven Riley, a professor of infectious disease dynamics at Imperial College London, said there was still enough time to curb the Indian variant wave if people got jabbed now.  

A University College London study of 8,517 people in England and Wales found 96.42 per cent of adults develop the virus-fighting molecules 28 to 34 days after their first Covid vaccine dose. Pictured: A woman receives her first vaccine dose in Bolton on Saturday, where the roll-out has surged in order to combat increasing cases of the Indian variant

He told BBC Radio 4’s Today programme: ‘If people decide this week to get a vaccine their antibodies are going to grow pretty strongly over the next two or three weeks and that would be the same period of time, if there is an increase in the number of infections, that their risk increases.

‘If you look two or three weeks down the road, the decisions that people make today about choosing to have a vaccine will directly affect them.’

AstraZeneca and Pfizer’s jabs work equally well at forcing the body to make antibodies that can fight off the disease, a study has found.

University of Birmingham research adds to evidence that the Britain’s gamble to space out doses works in the real world. It also proves it works for elderly people who notoriously have weaker immune systems and respond less well to vaccines.

The study also found AstraZeneca’s jab triggered a slightly longer-lasting response from white blood cells, which is another crucial part of the immune system. Levels are boosted by the second jab, however.

Dr Helen Parry and Professor Paul Moss, who did the research, said understanding what happens after one dose gives an idea of what protection people have now. 

Out of 32.3million people vaccinated across the UK, only 7.9million have had their second jab because of a policy to stretch the gap between them to 12 weeks.

This study shows that most people show signs of long-lasting protection from the virus even if they don’t get a second dose within three weeks as people did in trials.

Testing the blood of 165 people for Covid antibodies found 93 per cent of people had the virus-fighting proteins five to six weeks after their first Pfizer jab, and 87 per cent after AstraZeneca.

‘These vaccines are equivalent in producing protection after one dose,’ Professor Moss said.

‘They are equivalent and both vaccines are good.’ 

The percentage of people with antibodies shows that most people’s immune systems respond to the vaccines, but can’t tell us how well protected they are because scientists don’t know exactly how the body stops the virus

Dr Maddie Shrotri, lead author of the UCL paper currently under peer review, hailed the findings as ‘remarkable’ given how quickly the vaccines were developed.

She told the Guardian: ‘This is one of the earliest real-world vaccine studies in the UK and it is fantastic news.

‘Over nine out of 10 adults in the UK who had either the Pfizer or AstraZeneca vaccine produced antibodies against the virus within a month of their first shot.

‘How well these vaccines work is remarkable, especially given the speed at which they’ve been developed. It’s a real feat of science in the face of the most devastating pandemic in a century.’

The UCL study showed one dose of the vaccine stimulated antibody production less in older people than younger ones.

This is because as people age their immune systems find it more difficult to mount an immune response. This also explains why they are more vulnerable to Covid in the first place.  

Antibody levels after one dose were also lower in people with cancer, diabetes, heart disease and those who were taking  immune suppressing medication, for the same reasons.

But their antibody levels caught up with the general population after a second dose, the study found.

Professor Rob Aldridge, the chief investigator of the UCL Virus Watch Study, said the findings give ‘a timely reminder’ for everyone to have their second dose, particularly older people and those with pre-existing conditions.

But he added the results were ‘reassuring’ that the UK’s successful vaccine drive offers a route out of the pandemic.

The authors said the paper — which will be published in a medical journal after review — said people can only consider themselves ‘safe’ once they have had their second jab.

The percentage of people with antibodies shows that most people’s immune systems respond to the vaccines, but can’t tell us how well protected they are because scientists don’t know exactly how the body stops the virus. 

Antibodies are one part of the immune response, but white blood cells are also known to play a crucial role.

Some 36.7million people have had their first Covid jab in the UK, with 20.3million receiving a second shot by Sunday. 

The study comes after research last Friday showed Pfizer’s vaccine generates antibody responses three-and-a-half times larger in older people when a second dose is delayed to 12 weeks after the first.

The University of Birmingham study released on Friday was the first to directly compare immune responses of the Pfizer shot from the three-week dosing interval tested in clinical trials and the extended 12-week interval that British officials recommend in order to give more vulnerable people at least some protection quickly.

After the UK moved to extend the interval between doses, Pfizer and vaccine partner BioNTech said there was no data to back up the move. 

But Pfizer has said that public health considerations outside of the clinical trials might be taken into consideration when choosing dose timing. 

The UK Government announced last week it was shortening the second dose regimen for millions of vulnerable people living in Indian variant hotspot areas.

Ministers said the benefit of getting people fully protected in case there is a third wave outweighed the slight increase in effectiveness of the vaccines when given 12 weeks apart.

These people will now receive their follow-up dose at eight weeks, instead. 

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