Most people who recover from Covid are immune to the disease for at least six months, a major Government-backed surveillance study suggests.
The UK Biobank study found high levels of Covid antibodies – virus-fighting proteins made by the body after vaccination or prior infection – in the blood of nine in 10 patients half a year or more after testing positive.
Almost all of participants (99 per cent) had the same high concentration of antibodies three months following their initial infection.
It comes on the back of a growing body of studies, including from Oxford University and Public Health England, which also pointed to months-long immunity after recovering from Covid.
Sir Patrick Vallance, England’s chief scientific adviser, said the latest project, which recruited over 20,000 volunteers, was ‘useful confirmation’ that survivors are protected for at least half a year – but exactly how long the Covid immunity lasts is still one of the burning questions of the pandemic.
The scientists behind the Biobank study said Covid survivors should still continue to follow the lockdown rules because 10 per cent won’t enjoy protection and it’s not clear if former patients can still carry and spread the virus.
Professor Sir Rory Collins, an epidemiologist at Oxford University who led the study, said: ‘One aspect of this is whether or not they can still carry the virus and whether they can pass it to other people.
‘But we still don’t know whether they can still be a transmitter and put others at risk. We still cant be sure that this provides complete protection although studies from Oxford show it provides at least some protection.’
Professor Collins and his team also estimate nine per cent of the British population has been infected with Covid, the equivalent of six million people, which is almost double the Government’s official tally of 3.8million.
Above are the levels of Covid-19 antibodies in the blood over time by age and ethnic group. They reveal the levels remain high for at least six months after infection. Scientists are testing whether this could continue for longer
The highest estimated immunity levels were in London and the lowest in Scotland. But no region was near ‘hear immunity’, when enough people in the community are protected against the virus to stop the virus spreading
The study also found only 43 per cent of cases suffered at least one of the three recognised Covid-19 symptoms. But 40 per cent did not have any of them, and 24 per cent of these were asymptomatic – meaning they had no symptoms
The UK Biobank study collected blood samples and information on potential symptoms from 20,200 participants for six months to the beginning of December.
They found over the study period the proportion of Britain’s population thought to have antibodies against the virus rose by two per cent from 6.6 per cent in May to 8.8 per cent by December.
It is thought to be even higher now as Department of Health data shows the second wave only peaked at the end of December before declining.
The levels were highest in London, at 12.4 per cent, the West Midlands, at 9.7 per cent, and North West, at 9.4 per cent.
They were lowest in Scotland, at 5.5 per cent, the South West, at 5.8 per cent, and Wales, at 5.9 per cent.
Younger people were more likely to have antibodies against the virus than those in older generations, at 13.5 per cent in the under 30s to 6.7 per cent in those over 70.
Those in the Black ethnic group were most likely to have protection against the virus, at 16.3 per cent, while it was lowest among the White group at 8.5 per cent and China at 7.5 per cent.
There was no difference in antibody levels between genders.
The study also found the three NHS earmarked symptoms of the virus only came up in 43 per cent of cases, while 24 per cent of other infections were asymptomatic – meaning there were no warning signs – and 40 per cent did not have the three main symptoms.
UK Biobank Chief Scientist, Professor Naomi Allen, said: ‘We are incredibly grateful to all the UK Biobank participants, and their children and grandchildren, who provided us with their blood samples for six months.
‘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.’
Health Minister Lord Bethell, said: ‘This government-backed study provides further valuable insight into antibodies and increases our understanding of the virus, and I want to thank all of the talented researchers and everyone who volunteered to take part.
‘While the findings offer some promise, now is not the time for complacency. We still do not fully understand how long protection from antibodies may last, and we know people with antibodies may still be able to pass the virus on to others.
‘Right now, it remains vital for everyone to stay at home, even if you have had COVID-19 in the past, so we can stop the spread of the virus, protect the NHS and save lives.’
It comes after Public Health England also said that studies suggest immunity could last for six months after an infection
It comes after a Public Health England study published in November also said those that survive an infection could be protected against the virus for at least six months.
The findings may mean people who have already had the virus are less likely to get reinfected if they come into contact with the virus again.
A group of more than 2,000 people working for Public Health England volunteered to take part in the study and donate blood every month, with the first people recruited in early March, before lockdown was announced.
A total of 100 people tested positive for SARS-CoV-2, the virus which causes Covid-19, but none were hospitalised. More than half (56 per cent) had symptoms.
The study focused on a specific type of immune response, called T cells, which are created by the body following infection. They are different to antibodies but are just as pivotal in fighting disease.
The scientists behind the research call their findings encouraging and are ‘cautiously optimistic’ there is long-lasting and robust immunity following coronavirus infection.
The UK Coronavirus Immunology Consortium (UK-CIC) worked with PHE on the study and asked colleagues to be tested for the virus and take part in the study.
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