A study funded by the British government suggests that immunity against COVID-19 declines more quickly than scientists had hoped.
Conducted by Imperial College London and the Ipsos Mori polling institute, the study surveyed more than 365,000 adults in England who used at-home finger-prick antibody tests and found “a significant decline in the proportion of the population with detectable antibodies over three rounds of national surveillance.”
According to the study, the percentage of people who tested positive for COVID-19 antibodies fell by more than one-quarter between June 20, three months after the United Kingdom’s peak caseload, and Sept. 28. In June, roughly 6% of those who participated in the study had detectable COVID-19 antibodies. By late September, only 4.4% of participants had detectable antibodies. The non-overlapping community samples collected were sent out randomly to adults on a National Health Service patient list, “which includes anyone registered with a General Practitioner in England.”
The study has not been peer-reviewed yet, and scientists have not confirmed that COVID-19 antibodies are effective enough to prevent reinfection. The study did suggest that, like other viral disease responses, the severity of the disease correlated with a patient’s immune response. People who displayed symptoms were more likely to have detectable antibodies than asymptomatic patients.
The study also found younger adults, aged 18-24, lost antibodies at more than half the rate of the oldest participants. Positivity in younger adults fell 14.9%, according to the study, whereas adults aged 75 and older experienced a 39% decline in detectable antibodies.
Healthcare workers did not experience a noticeable decrease in detectable antibodies between June and September.
The study noted that antibodies are only one part of the body’s response to the coronavirus, adding it is still unclear how T cells and non-virus-specific immune system responses contribute to immunity and a patient’s ability to fight the disease.
“It is not possible to say with certainty that the loss of antibody positivity in the LFIA would correlate with an increased risk of an individual being reinfected,” the study said. “However, at a population level, the waning we have observed may indicate an overall decline in the level of population immunity.”