Blow to herd immunity hopes as antibody levels drop

Scientists at Antwerp University have tested a random selection of blood samples for the presence of coronavirus antibodies that reveal contact with the virus.  They came to the surprising conclusion that only 5.5% of people still had coronavirus antibodies.  In earlier tests figures of up to 7% were recorded.

It’s the fourth time that Antwerp scientists carry out this antibody test on blood samples taken from patients at random and not because they were suspected of having coronavirus.  2,960 samples were tested originating from patients providing blood samples between 8 and 13 June.  Earlier tests carried out before and during the lockdown revealed an increasing number of samples containing antibodies from nearly 3% over 6% to nearly 7%.  The latest test revealed a drop in the presence of antibodies that indicate contact with coronavirus.

Prof Pierre Van Damme says the result wasn’t anticipated: “We expected a figure that was at least as high as the last 7% given the presence of the virus and the relaxations.  The epidemiologist sees two explanations: some patients had been in contact with coronavirus, but the antibodies that were in their blood had already disappeared.  Earlier research already indicated a reduction in antibodies after one to two months.  Secondly, Prof Van Damme suggests the result may indicate people are sticking to good hand hygiene and social distancing even after the lockdown and that the figure is lower as a result.

A speedy disappearance of antibodies that afford protection against a second infection, isn’t heartening news.  It also means that scientists won’t be able to bank on herd or community immunity to counter coronavirus.   

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