Coronavirus cases fell by 12.5% in the first full week of the New Year in what the public health agency RIVM called the first clear sign that the month-long lockdown is taking effect.

In the week to Tuesday 49,398 positive tests were recorded, compared to 56,440 in the previous seven days. The positive test rate was 12.8%, still relatively high but the lowest proportion since the first half of December.

The government is expected to announce a three-week extension to the lockdown on Tuesday evening because infections have not come down sufficiently to allow schools, non-essential shops and facilities such as museums and gyms to reopen.

Although infections have fallen steadily in the last two weeks, the number of patients in hospital and intensive care remains higher than at any time since April last year. In the last seven days 1,503 people were admitted to hospital with Covid-19, a decline of 18.2%, while intensive care admissions were 11.9% lower at 297.

The RIVM said the decline in positive tests was concentrated in people over the age of 30. In the 18-to-24 age group infections per 100,000 people increased by around 10%.

The reproductive number R, which indicates whether the virus is becoming more prevalent or declining, remains just below 1 at 0.95, as calculated on December 25.

Around the 25 safety council regions the highest concentration of cases was in Twente, where 417.8 in every 100,000 people tested positive last week, while Rotterdam-Rijnmond had the lowest rate at 194.3.

The declining trend was also reflected in the daily figures for Tuesday, with the number of new infections falling below 5,000 for the first time since December 2. A total of 4,986 cases were recorded, 21.3% fewer than a week ago, bringing the weekly average down to just over 7,000.

However, there is little respite so far for the hospitals, who are currently treating 2,640 patients with Covid-19, an increase of 12 since Monday, of whom 695 are in intensive care.