“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.
There are four other human coronaviruses, which we catch multiple times in our lives. They cause common cold symptoms and we can be reinfected every six to 12 months.
There have been very few confirmed cases of people getting Covid twice . However, the researchers warn this may be due to immunity only just starting to fade since the peak infection rates of March and April.
The hope is the second infection will be milder than the first, even if immunity does decline, as the body should have an “immune memory” of the first encounter and know how to fight back.
Professor Paul Elliott, director of the REACT-2 study, said it would be wrong to draw firm conclusions from the study about the impact of a vaccine.
He said: “The vaccine response may behave differently to the response to natural infection.”
