Immunity to Covid-19 could disappear just weeks after you get the virus, new research suggests.
According to the study, patients who tested positive for the virus saw a drop in the amount of Covid antibodies in the weeks and months after they were infected.
The Imperial College London and Ipsos MORI research suggests that our immunity to the virus - currently affecting countries across the world - declines over time.
More than 365,000 randomly selected adults tested themselves at home using a finger prick test between 20 June and 28 September to check if they had antibodies against Covid-19.
During this period, the proportion of people who tested positive for Covid-19 antibodies declined by 26.5%, suggesting antibodies reduce in the weeks or months after a person is infected.
It also found that people who didn't suffer symptoms while infected with the virus are more likely to lose Covid antibodies.
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This means that if you were asymptomatic you could be more likely to be infected by the virus a second time.
People aged over 75 will also lose their antibodies faster than those aged 18-24.
Health Minister Lord Bethell said: “This study led by Imperial and Ipsos MORI is a critical piece of research, helping us to understand the nature of Covid-19 antibodies over time, and improve our understanding about the virus itself.
"We rely on this kind of important research to inform our continued response to the disease, so we can continue to take the right action at the right time.
“It is also important that everyone knows what this means for them – this study will help in our fight against the virus, but testing positive for antibodies does not mean you are immune to Covid-19.
“Regardless of the result of an antibody test, everyone must continue to comply with government guidelines including social distancing, self-isolating and getting a test if you have symptoms and always remember Hands, Face, Space.”
Professor Paul Elliott, Director of the REACT programme at Imperial from the School of Public Health, said: “Our study shows that over time there is reduction in the proportion of people testing positive for antibodies against the virus that causes Covid-19.
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"It remains unclear what level of immunity antibodies provide, or for how long this immunity lasts.
"If someone tests positive for antibodies, they still need to follow national guidelines including social distancing measures, getting a swab test if they have symptoms and wearing face coverings where required.”