The Dutch blood bank Sanquin has not yet been able to collect enough blood plasma from donors who have had coronavirus to be able to make a potential medicine to treat sufferers, the AD reported on Monday.

Sanquin had appealed for some 16,000 donors to come forward in an effort to collect 30 tonnes of plasma containing coronavirus antibodies. But although 20,000 donations have now been made, so far only 8,000 to 9,000 kilos of plasma have been collected, and some of that may not now be suitable.

This, the blood bank told the paper, is because the volume of antibodies in some samples is extremely low or the antibodies have disappeared altogether.

‘We need plasma with a high concentration of antibodies to make the medicine and we had expected that the volume of antibodies would stay high for longer,’ microbiologist Hans Zaaijer, who works with Sanquin, told the paper.

The Dutch health ministry has put €10m into the Sanquin project. The aim is to give the plasma to vulnerable patients who have just been diagnosed with coronavirus to see if it reduces their symptoms, and potentially, to give it to nursing home residents if there is an outbreak.

The plasma may also be useful for people with a poorly functioning immune system, such as kidney patients and people who have had chemotherapy. ‘Their bodies are not in a position to make antibodies, so giving them plasma could make all the difference,’ Zaaijers said.