Coronavirus antibodies last for at least six months after infection for the majority of people who have had the virus, according to a new study.

It found 99% of participants who had tested positive for previous infection retained Covid antibodies for three months after being infected, while 88% did so for the full six months of the study.

The research also found that 8.8% of the UK population had been infected by December 2020, rising as high as 12.4% in London and as low as 5.5% in Scotland.

The study from UK Biobank, the UK’s major biomedical database and research resource, measured the levels of previous infection in various population groups across the UK as well as how long antibodies persisted in those who were infected.

Researchers concluded that antibodies produced following natural infection may provide a degree of protection for most people against getting infected again for at least six months.

UK Biobank chief scientist, Professor Naomi Allen, said: ‘This important study has revealed that the vast majority of people retain detectable antibodies for at least six months after infection with the coronavirus.

‘Although we cannot be certain how this relates to immunity, the results suggest that people may be protected against subsequent infection for at least six months following natural infection.

‘More prolonged follow-up will allow us to determine how long such protection is likely to last.’

The most common symptom associated with having coronavirus antibodies was a loss of sense of taste and smell, which was reported by 43% of sero-positive participants.

Around one quarter (24%) of sero-positive participants were completely asymptomatic, and 40% did not have one of the three classic Covid-19 symptoms – fever, persistent dry cough or loss of sense of taste or smell.

But the researchers warned that just because people have built up an antibody response, it does not mean they cannot still pass the virus on to others.

Professor Sir Rory Collins, UK Biobank principal investigator, said: ‘Both with vaccines and indeed with past infection, we don’t yet know what impact that has on the ability to be carrying the virus and transmitting to others.

‘So I think one important message both for people who have been infected, and for people being vaccinated, is you may be protected, to some extent, but you may still put others at risk.

‘So it’s important to maintain the social distancing and the lockdown measures in line with the Government guidance.’

He added that the findings support the Government’s decision to delay second doses of Covid-19 vaccines for up to 12 weeks.

It comes as a separate study found a single dose of the Oxford vaccine may be 76% effective at preventing symptomatic illness and have a ‘substantial effect’ on transmission, new research suggests,

The study provides a major boost to the UK’s recommendation that the second jab should be delayed for up to 12 weeks.

Scientists said that the first dose of the Oxford/AstraZeneca jab offers protection of 76% up to three months and may reduce transmission by 67% – with efficacy rising to 82.4% after the second dose 12 weeks later.

This indicates that those who have been vaccinated are not only protected from the disease, but that they are not likely to pass on the virus to anyone.

Before these results, little was known about how effective the Covid-19 vaccines were at preventing transmission of the disease.

The data from the study by the University of Oxford, which has not yet been peer reviewed, supports the four to 12-week prime-boost dosing interval that many global regulators, including the UK’s, have recommended.

The study also suggests the vaccine eliminates severe illness, as none of those in the study were admitted to hospital with coronavirus.

Professor Andrew Pollard, chief investigator of the Oxford Vaccine Trial and study co-author, said: ‘These new data provide an important verification of the interim data that was used by more than 25 regulators including the MHRA (Medicines and Healthcare products Regulatory Agency) and EMA (European Medicines Agency) to grant the vaccine emergency use authorisation.

‘It also supports the policy recommendation made by the Joint Committee on Vaccination and Immunisation (JCVI) for a 12-week prime-boost interval, as they look for the optimal approach to roll out, and reassures us that people are protected from 22 days after a single dose of the vaccine.’

The findings suggest that what has a greater impact on the efficacy of the vaccine is the time between doses and not the dosing level.

Researchers say this is in line with previous studies into other vaccines such as influenza, Ebola and malaria.

A former chair at the Faculty of Pharmaceutical Medicine, Dr Gillies O’Bryan-Tear, said the results were the first definitive estimate of the impact of vaccination on transmission rates.

‘If the effect on transmission is confirmed for the Pfizer vaccine too, this would be very positive,’ he said.

Health Secretary Matt Hancock and Prime Minister Boris Johnson have also welcomed the results of the study, which came as Public Health England (PHE) said it was investigating strains of coronavirus in the UK which have developed a mutation that has been worrying scientists.

Eleven cases in the Bristol area have been identified as the variant that originally arose in Kent but are now showing the E484K mutation after morphing again.

A cluster of 32 cases in Liverpool also have the same mutation but relate to the original strain of coronavirus that has been around since the start of the pandemic.

Meanwhile the South African variant – which also shows the E484K mutation – is under investigation in at least eight postcode areas of England where cases not linked to travel have been found.

The E484K mutation has been shown to reduce the effectiveness of vaccines in preventing people contracting Covid-19.

However, public health experts believe current vaccines will still be effective against strains with the mutation, although at a lower level, and are good at preventing severe disease.

Government data up to February 1 showed of the 10,143,511 jabs given in the UK so far, 9,646,715 were first doses – a rise of 350,348 on the previous day’s figures.

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