The figure, published by agency State Serum Institute (SSI), is some way higher than the previous record of 4,508 cases set on December 18th, 2020.
Late November saw daily case totals hover around 4,000 and approach 4,500 on several occasions without exceeding it.
But Wednesday’s high number comes one day after Health Minister Magnus Heunicke said there were signs the current wave of infections was “becoming stable”.
The figures reported on Wednesday are surprising, according to Kasper Karmark Iversen, senior medical consultant and professor at the University of Copenhagen and Herlev-Gentofte Hospital.
“It has otherwise been stable for some time so it’s surprising to suddenly get such an increase,” Iversen told news wire Ritzau.
“But I don’t think too much should be taken from it. It could be an outlier before we go back to the normal level tomorrow,” he said.
The 5,120 new cases come from 195,137 PCR tests, giving positivity rate of 2.62 percent.
Compared with Tuesday’s numbers, the raw figure is much higher – 4,148 cases were reported on Tuesday. But the positivity rate is comparable, having stood at 2.58 yesterday.
Hospitalised patients with Covid-19 in Denmark now number 439, an increase of six compared to Tuesday.
The strain on hospitals can be felt, despite this number being lower than the peak hospitalisation figures from the winter 2020 wave, which exceeded 900.
“There are not catastrophic conditions yet but we have a combination of an tangible lack of nurses combined with this strain. It is clearly putting pressure on hospitals,” he said.
A further two cases of the new Omicron variant were meanwhile confirmed on Wednesday. The variant has now been detected six times in Denmark since it was first identified and reported to the international community by South Africa at the end of last week.
Five of the six cases have been traced to travel to South Africa, and one case traced to travel from Qatar.
Three further suspected cases have been found not to be Omicron, and 11 more await results of genome sequencing.