More than 200,000 people tested positive for coronavirus in the first full week of January, a record figure and 77% higher than the previous week.

The latest weekly bulletin from the public health agency RIVM shows the Omicron variant causing a surge in infections, but hospital admissions are continuing to decline steadily.

The rise in positive tests was concentrated in younger age groups, with infections more than doubling in people aged 15 to 30. Around one person in 30 in the 20-25 age group had a positive test in the last week.

By contrast, cases rose marginally or even declined in older generations, with fewer than one in 500 people over 75 testing positive.

More than one in three tests (34.2%) was positive, the highest proportion recorded in a single week since mass testing began.

There was also considerable variation between regions, with the infection rate ranging from 630 per 100,000 people in southern Limburg to more than 2,000 in Amsterdam, where an estimated 99% of infections are caused by Omicron.

The RIVM said Omicron was now thought to be the dominant strain in the Netherlands, although comprehensive data is only available up to December 26, when it accounted for 28% of cases.

The figures also show an unprecedented number of people are catching the virus for the second or subsequent time. Reinfections accounted for around 3% of the total until mid-December, but that proportion shot up to 13% in the first week of January.

The R value of Omicron is estimated to be more than double that of the declining Delta variant, with reproduction rates of 1.63 for Omicron and 0.78 for Delta – meaning every three people with Omicron go on to infect five others.

Hospital admissions

The declining rate of hospital admissions has meant the number of people being treated for coronavirus has almost halved in the last month to 1,497, from a peak of 2,848 on December 9. The number of patients in intensive care fell by 10 on Tuesday to 395, the first time since mid-November that it has been below 400.

In the last seven days 893 people were taken to hospital with Covid-19, while 143 were admitted to intensive care. The figures for the previous week were 1,046 and 171 respectively.

Another 116 deaths were recorded by the RIVM, down from 189 the week before, though not all deaths are included in the figures from the GGD regional health network.