The amount of antibodies against coronavirus found in blood given by vaccinated blood donors has halved in two months, according to donation agency Sanquin.

The longer ago people were vaccinated, the fewer antibodies they have, Sanquin said, following research on blood donated by 2,200 people. People in their early 60s, who were given the AstraZeneca vaccine, have the fewest antibodies, Sanquin said.

The Dutch government has decided to shorten the length of time before people can apply for a booster vaccination from six to three months, and now hopes to have offered everyone who wants a booster an appointment by mid January.

‘Antibodies for respiratory infections usually decrease quickly over time,’ said microbiologist and researcher Hans Zaaijer.

‘In previous research, we saw that the amount of anti-Covid-19 antibodies halves approximately every three months,’ he said. ‘Our most recent study among Dutch blood donors also shows this. We hope that there will be a plateau, so that the antibodies do not disappear completely. But we don’t see that reflected in the numbers yet.’