The REACT study is using finger-prick testing to detect coronavirus antibodies in the blood. When present these indicate that a person has been previously infected with the virus. 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.
The tests are sent out to randomly-selected adult volunteers across the country to carry out at home.
The latest report includes findings from three rounds of testing carried out over a three-month period. There were 17,576 positive results across all three rounds, around 30% of whom did not report any COVID-19 symptoms. After accounting for the accuracy of the test, confirmed by laboratory evaluation, and the country's population characteristics, the study found that antibody prevalence declined from 6.0% to 4.8% and then 4.4% over the three months.
This was found across all ages but the smallest drop was found in the youngest age group, aged 18-24, falling from 7.9% to 6.7% (14.9%), while the largest was found in the oldest group, aged 75 and above, declining from 3.3% to 2.0% (39%).
Professor Helen Ward, one of the lead authors of the report said: "This very large study has shown that the proportion of people with detectable antibodies is falling over time. 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."
francamente da questi studi si può evincere poco. che in tot mesi il titolo anticorpale scenda è risaputo. le cellule dell'immunità entrano in quiescenza e le poche con memoria in giro fanno da "ronda"
