The proportion of citizenry in England with antibody after Covid-19 contagion dangle by more than a quarter over three calendar month , a new bailiwick has record , suggesting people ’s immune response to SARS - CoV-2 wanes over time .

The findings from theREACT-2   studyled by Imperial College London present that the bit of people who tested positive for antibodies at the end of September had dropped by 26.5 per centum compared to mental testing carried out mid - June , going from just under 6 percent of those tested demo antibodies to 4.4 percent . This betoken masses ’s resistant reception to Covid-19 diminishes over time , and the level of unsusceptibility in a universe declines after the first undulation of an epidemic .

The REACT study , an antibody surveillance study that tracks past Covid infection across England using dwelling house finger - dent trial , publish itsfirst Seth of datafrom 100,000 participant back in August , prove that just under 6 percent of those screened between June 20 and July 13 had antibody .

Now , new datahas been released ahead of peer - review that shows after a second one shot of testing antibody levels dropped to 4.8 percent , and a third circle show that for those tested between September 15 and 21 , the bit dropped again to 4.4 percent .

Each round had over 100,000 adult participant , with answer from 365,000 hoi polloi in sum from all part of England , selected at random . The descent in antibodies – blood protein create by the body in response to an attacking antigen – was seen across all age chemical group , but the largest drop was seen in the 75 + age chemical group ( a decline of 39 percent ) and the smallest in the 18 - 24 geezerhood group ( 14.9 percent ) .

The results also show that symptomless infections appeared to lose noticeable antibodies faster than those who display Covid-19 symptoms .

antibody would be expected to wane over time , as they do with other coronaviruses , like the vulgar frigidness , but how fast and how far they accrue is unknown for Covid-19 . It is also not yet jazz what level of antibody is needed for someone to be protected from contagion or reinfection of Covid-19 .

“ Our study shows that over time there is a simplification in the proportion of people testing incontrovertible for antibodies,”saidImperial ’s Professor Paul Elliot . However , “ Testing positive for antibody does not think you are immune to Covid-19 . It remains unclear what level of unsusceptibility antibodies provide , or for how long this immunity lasts . ”

This does not necessarily mean that resistance from vaccination would be short - lived , but it does undermine the estimation that by nature occurring herd immunity among a population is a viable response to Covid-19 , something already indicated inresults from Sweden , one of the few countries that did not impose a lockdown in the Leslie Townes Hope of attain herd immunity . Swedish epidemiologist had expect around 40 percentage of the res publica to have educate antibodies by May after the virus first reached it in March , and were surprised to find just 6.1 percentage of the population had . It’scurrently estimatedthat without a vaccine , 60 percent of a population would take to be protect against Covid-19 for it to check the spread .

The React-2 data is yet to be equal - review , so more data will be needed to verify its finding , but antibody are still a good indicator of protective covering against reinfections . Though reinfection caseshave been reported , they are rare , which may be because it ’s still too before long for antibody to have declined to the spot of people becoming susceptible to the transmission again   – something we will key with time .

“ We do n’t yet know whether this will leave these people at risk of infection of reinfection with the virus that do Covid-19 , " Professor Helen Ward , one of the sketch ’s lead writer , tell , " but it is essential that everyone continues to keep an eye on guidance to reduce the risk to themselves and others . ”