Covid UK: 90% over-80s still have antibodies six weeks after a single vaccine dose, study shows

Nine out of 10 people over 80 still had strong signs of coronavirus immunity six weeks after their first vaccine dose, a study has found.

And both AstraZeneca and Pfizer’s jabs work equally well at forcing the body to make antibodies that can fight off the disease.

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.

The latest research by the University of Birmingham adds to evidence that the Covid vaccines are successful in the real world and work for elderly people who notoriously have weaker immune systems and respond less well to vaccines

The latest research by the University of Birmingham adds to evidence that the Covid vaccines are successful in the real world and work for elderly people who notoriously have weaker immune systems and respond less well to vaccines

‘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.

It does show, however, that people develop significant signs of immunity that lasts beyond the three-week target date that manufacturers set for second doses to be given.

Britain threw this advice out of the window and isn’t giving people their second jab until 12 weeks after the first.

The study adds to evidence that this move was the right one, with people’s immunity lasting well beyond three weeks and even improving over time.


Coronavirus vaccines made by Moderna and Novavax will be added to a ‘mix and match’ trial, scientists said today.

Britain’s medical regulator currently requires everyone to have two doses of the same jab, currently either AstraZeneca, Pfizer or Moderna.

But Oxford University experts are testing whether giving a second dose different to the first one could provoke a stronger immune response.

Their trial — which could revolutionise Britain’s roll-out — was already assessing the effects of combining doses of AstraZeneca and Pfizer.

Another 1,000 volunteers will now be recruited to the study to test combinations including vaccines made by Moderna and Novavax.

Experts say mixing jabs is unlikely to pose any safety concerns and say it could lead to shots being even more effective at preventing an infection with the virus.

In the wake of AstraZeneca’s blood clot fears, France approved giving recipients an alternative second dose. Germany made the same move for under-60s.

But until evidence is gathered they can’t say for certain whether it works or whether it is safe.

Britain has only recommended under-30s are offered an alternative and that anyone who has already had their first dose should come forward for their second, unless they suffered the extremely rare complication.

Oxford’s mix-and-match trial was first launched in February.

Dr Parry said: ‘We know that both the Pfizer and AstraZeneca Covid vaccines show good real-world effectiveness but we also need to understand the underlying immune responses that they generate. 

‘This is particularly so in relation to the extended dose scheduling of up to 12 weeks between vaccinations and its impact in older people.

‘In our study we were able to detect antibody responses in most people aged 80 or above, five weeks after a single dose of either.’

She added in a briefing today: ‘It’s encouraging but it’s not known exactly what that level is that gives you clinical protection.’

Some people who test positive for antibodies may still get infected and become sick if their immune response isn’t strong enough – the likelihood or danger of this happening is still a mystery to scientists.

The Birmingham study, done alongside the UK Coronavirus Immunology Consortium, tested the blood of 165 people over the age of 80.

Each had received one dose of a coronavirus vaccine between five and six weeks before their blood test: 76 with the Pfizer jab and 89 with AstraZeneca’s.

The tests looked for virus-fighting substances called antibodies, which they found in around nine out of 10 people, and white blood cells called T-cells, which were less common.

Only 12 per cent of people had developed a T-cell response that showed up in the blood tests after the Pfizer jab, compared to 31 per cent after AstraZeneca.

Although the numbers appear low, Dr Parry and Professor Moss said they didn’t know exactly what this meant for someone’s real-world protection against Covid.

And the fact that levels were undetectable doesn’t mean they weren’t there, nor that someone doesn’t have other types of immunity.

T-cells generally take longer to develop – they also last longer – and they are not thought to be the main protection against the virus.  

‘We think that antibodies might be more important against infection and reinfection,’ said Professor Moss.

‘Ninety per cent have developed an antibody response and that’s the take-home message from this study.’

Another finding of Professor Moss and Dr Parry’s study was that people who had been infected with coronavirus in the past had a much stronger immune response to the vaccine.

Only eight people in the study were in this category but blood tests suggested they produced over 600 times as many antibodies as people who never had Covid.

Professor Eleanor Riley, an immunologist at Edinburgh University, who was not involved with the research, said: ‘However, the much higher immune responses in people who have previously had Covid-19 shows that stimulating the immune system twice – in this case, through infection and then through vaccination – induces a much more potent and likely much longer lasting response. 

‘Assuming that a similar effect is seen after two vaccinations, as expected from the clinical trial data, this really underscores the importance of having the second vaccination.’ 

The study was published online at Preprints with The Lancet.