Antibody responses to the coronavirus may decrease over time, according to a study that showed natural defenses diminished in Britons who had previously been exposed.
Of the 365,000 randomly selected British adults who tested themselves at home, 4.4% had antibodies in September, up from 6% in June, according to a study released Tuesday by Imperial College London and the Ipsos MORI survey service. .
The study suggests that the antibodies, a marker of exposure to the coronavirus, may not last in all people who have been infected, adding to other research indicating that immunity may be limited.
A small but growing number of patients have fallen ill with Covid-19 twice, and it is not known how long the protection of antibodies against a vaccine will last. There are also some protective injections in development that aim to stimulate so-called T cells capable of fighting viruses.
The study showed that people who tested positive but did not show symptoms of Covid-19 appeared to lose antibodies more often than those who suffered from the noticeable effects of the disease.