Some 40% of registered coronavirus cases in Amsterdam are now thought to be the Delta variant, according to local health board research, based on a preliminary analysis of some 100 samples.

Two weeks ago, just 7% of cases in the capital were Delta and public health institute RIVM said on Tuesday it expects the strain will be dominant nationwide within a few weeks.

The new variant is mainly being observed by youngsters who have ‘brought it back from holiday’, a spokesman told broadcaster NOS. An average of 55 new cases of coronavirus a day are being reported in Amsterdam.

In total, 679 new cases were reported in the 24 hours to Wednesday morning, down 25 on Tuesday. Wednesday and Thursday usually have more cases than other days of the week because of the weekend catch up.

Meanwhile, the number of coronavirus patients being treated in hospital has fallen to 425, of whom 170 are in an intensive care ward.

The RIVM expects the decline in hospital admissions to continue throughout the summer, although this may change in the autumn if the Delta variant takes hold.

The health ministry’s dashboard shows 14.3 million doses of vaccine have now been administered in the Netherlands and that officials are on target to vaccinate 1.5 million people this week.