The number of blood donors with coronavirus antibodies in their bloodstream is falling, according to the latest analysis by blood bank operator Sanquin.

Just 4.1% of samples in the most recent batch contained antibodies, indicating that someone has been infected and developed resistance to the virus, compared to 5.3% a month ago.

The trend is in line with other countries where resistance to the virus appears to be diminishing, and represents a setback for hopes that the disease can be contained through natural immunity.

It is not known if former patients who no longer have antibodies in their blood are at risk of contracting the disease again. ‘After an infection of this kind the body’s immune system also builds up a memory,’ said microbiologist Hans Zaajer to Trouw. ‘That means that a new infection can lead to antibodies rapidly developing. The virus can then be quickly flushed out.’