STOCKHOLM, Jan 7 (Reuters) - Sweden set a new daily record for COVID-19 cases for the third time this week, registering 23,877 cases on Jan. 5, health agency data showed on Friday, as a fourth wave swept the country and piled pressure on its healthcare system. The mounting wave of COVID-19 cases is increasingly driven by the more contagious Omicron variant and has seen hospitalisations rise rapidly in many parts of the country, although deaths have remained relatively stable so far. Sweden, which has spurned hard lockdowns through the pandemic, tightened restrictions on public gatherings last month and has urged all who can to work from home in an effort to minimize the spread of the virus. read more Bars and restaurants may only serve seated guests while the public also has to be seated at larger events. Still, the case load has continued to surge, raising the prospect of a further tightening, such as imposing vaccination passes more broadly. While case numbers have surged, hospitalisations for COVID have climbed but remain well below peaks in previous waves, with the number of intensive care patients hovering just above 100. Just over 82% of Swedes aged 12 or above have been double vaccinated, while around a third of adults have had a booster. However, the fresh wave of COVID cases has combined with the strain of seasonal flu admissions and large numbers of staff being off sick or isolating to heap pressure on healthcare services which are being tested by repeated virus outbreaks.