Nearly everyone who overcame the coronavirus showed signs of immunity against the infection three months later in a new study.
Scientists from UK Biobank arranged for more than 20,000 adults and children to provide at-home blood samples once a month between May and December 2020.
Of the 705 participants who tested positive for the coronavirus or showed signs of immunity at the start of the study, 700 (99.2%) produced antibodies against it three months later.
More than four in five (87.8%) continued to produce antibodies six months post-infection, the results add.
Antibodies are infection-fighting proteins released by the immune system after it overcomes a virus to help prevent the infection taking hold again.
The scientists are optimistic their results “indicate the antibodies produced following natural infection may provide a degree of protection for most people against subsequent infection for at least six months”.
They did not measure antibody response after vaccination or against the recently emerged coronavirus variants.
“These latest results provide useful confirmation of the maintenance of antibodies to SARS-CoV-2 over six months,” said Sir Patrick Vallance, the UK’s chief scientific adviser.
“Having the results of the study available within UK Biobank’s rich resource will allow further understanding of the disease impact over time.”
Since the coronavirus emerged, experts have questioned the extent to which overcoming the infection protects an individual from catching it again.
A “remarkable” study by the University of Washington in August 2020 raised hopes when three people who had already fought off the coronavirus did not become reinfected during an outbreak on a fishing vessel.
The UK Biobank research was carried out to improve immunity understanding, however, the scientists only looked at the participants’ antibodies, excluding other aspects of the immune response, like T-cells.
T-cells may be studied in follow-up research in the coming months, funding permitted, according to the team.
Follow-up analyses will also allow the scientists to better understand how long immunity may last.
Lord Bethell, from the department of health and social care, added: “This government-backed study provides further valuable insight into antibodies and increases our understanding of the virus.
“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 [the disease caused by the coronavirus] in the past, so we can stop the spread of the virus, protect the NHS and save lives.”
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The results further show the proportion of the participants with coronavirus antibodies rose from 6.6% in May to June, to 8.8% by the end of the year.
Antibody prevalence peaked in London, at 12.4%, compared to an average of just 5.5% in Scotland.
Rates did not vary between genders, however, antibodies were more common among those under 30 at 13.5% versus 6.7% in people over 70.
Antibodies were also found to be highest among people of a Black ethnicity (16.3%), and lowest among those of white (8.5%) and Chinese (7.5%) ethnicities.
A loss of taste and smell was the most commonly reported symptom in the Biobank study, affecting more than two in five (43%) of those with antibodies.
Just under a quarter (24%), however, reported having no symptoms, while 40% did not have the supposedly tell-tale fever, cough or muted senses.
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