More from the article...
...The Imperial College London team found the number of people testing positive for antibodies has fallen by 26% between June and September.
They say immunity appears to be fading and there is a risk of catching the virus multiple times.
The news comes as figures from the Office for National Statistics show that the number of Covid-19 deaths in the UK rose by 60% in the week of 16 October....
In the first round of testing, at the end of June and the beginning of July, about 60 in 1,000 people had detectable antibodies.
But in the latest set of tests, in September, only 44 per 1,000 people were positive.
It suggests the number of people with antibodies fell by more than a quarter between summer and autumn.
"Immunity is waning quite rapidly, we're only three months after our first [round of tests] and we're already showing a 26% decline in antibodies," said Prof Helen Ward, one of the researchers.
The fall was greater in those over 65, compared with younger age groups, and in those without symptoms compared with those with full-blown Covid-19.
The number of healthcare workers with antibodies remained relatively high, which the researchers suggest may be due to regular exposure to the virus. ...