The testing kits, called Lateral Flow Tests, detect antibodies above a particular concentration in the blood and do not measure the amount of antibodies in a particular person, according to Imperial College.
Although immunity to the novel coronavirus is a complex and murky area, and may be assisted by T cells, as well as B cells that can stimulate the quick production of antibodies following re-exposure to the virus, the researchers said the experience of other coronaviruses suggested immunity might not be enduring.
Around 60 in 1,000 people had detectable antibodies, in the first round of testing which was held at the end of June, beginning of July. Declining prevalence of antibody positivity to SARS-CoV-2: a community study of 365,000 adults MEDRXIV-2020-219725v1-Elliott.pdf.
Such results have delivered a blow to herd immunity - which, remember, is definitely not the government's real policy of dealing with the virus - due to fears over reinfection once recovery from coronavirus is complete.
The study suggests that the immune system's response to the virus is similar to its reaction to influenza and other coronaviruses such as the common cold, which can be contracted seasonally.
The hope for long-term immunity from COVID-19 was thrown into doubt on Tuesday as a large United Kingdom study concluded that protective antibodies in people fall "quite rapidly" after a coronavirus infection.
Levels of antibodies within the body decline rapidly within just a few months of contracting coronavirus, a new study from Imperial College London has found.
The React study found that people aged 18 to 24 had the highest prevalence of antibodies and lowest decline in antibody levels, at 14.9 per cent. Ward added in a statement, "We don't yet know whether this will leave these people at risk of reinfection with the virus that causes COVID-19, but it is essential that everyone continues to follow guidance to reduce the risk to themselves and others".
However, "it is not yet known whether the antibodies confer an effective level of immunity or, if such immunity exists, how long it lasts", specified the researchers, stressing the importance of continuing to respect the sanitary instructions.
A separate arm of the REACT study is using at-home swab tests to monitor levels of current infection, involving more than 150,000 people each month.
Alexander Edwards, from the University of Reading, says decreasing antibody levels are not necessarily the same as losing immunity, pointing out that antibody levels naturally decrease as people recover from an infection.
Riley also notes this research should not be used to imply vaccine-induced immunity would be short-lived.
One strategy these findings do question, however, is whether herd immunity can be achieved through natural infection. Vaccines contain immune stimulators, which she says induce durable immune responses in ways that can be different to natural infection.
This study has ominous implications for those who believe the pandemic can be brought to heel through herd immunity.