Omicron is now the dominant coronavirus variant in Switzerland and has even caused triple-jabbed people to be admitted to hospital, officials said Tuesday.

Switzerland has one of the highest infection rates in continental Europe, with people in their 20s the most affected, officials told a press conference in the capital Bern.

Around 55 percent of Swiss cases are now due to Omicron, and the variant is soon expected to represent almost all recorded infections.

The country has registered around 40 cases of people who had received a "booster" third vaccine dose but nonetheless ended up in hospital with the Omicron strain, said the health ministry's crisis management chief Patrick Mathys.

More than 13,000 new Covid-19 cases were announced Tuesday, with the figure expected to reach 20,000 per day in January.

Switzerland, a country of 8.6 million people, has recorded more than 1.27 million positive tests during the pandemic.

The wealthy Alpine nation is battling its fifth wave of the pandemic and Mathys said there was no respite in sight.

People must reduce their number of contacts due to Omicron, "but everyone can do it -- it's pretty simple," he said.

Covid-19 patients currently occupy 40 percent of the available intensive care beds.

Some hospitals are at full capacity but transfers to other hospitals were working well, said Rudolf Hauri, head of the cantonal medical chiefs' association.

"In terms of virulence, the Omicron variant seems weaker than Delta," said Tanja Stadler, head of the Covid-19 Scientific Task Force -- though this could be down to the level of vaccination among the population.

Some 67 percent of the Swiss population has received at least two vaccine doses, with 22 percent having had a third injection.