Denmark and Norway have announced stricter Covid measures to battle soaring infection numbers, as authorities said the new Omicron variant was spreading fast and would probably become dominant in several EU countries within weeks or even days. Amid a varied continental picture that includes sharply declining case numbers in many countries, the two Scandinavian governments said they expected daily infections would soon exceed all previous records as the highly transmissible variant combined with and fuelled a wave still largely driven by the previous Delta mutation. Denmark, which like Britain carries out extensive rapid genetic sequencing to detect variants, is second only to the UK in the number of confirmed cases of the mutation, with 3,473 cases identified in a population of 5.8 million of which 80.6% are double jabbed. The Danish government, which last week closed schools and colleges, curbed nightlife and promoted remote working, on Tuesday began offering booster shots to all over-40s six weeks earlier than planned in an effort to curb the spread of the virus. The national health authority on Monday reported a 50% increase in the number of new weekly cases, the highest since the start of the pandemic, with daily infections hitting 7,799, double the number on the same day last week. While the surge was driven mostly by the Delta variant, it said Omicron was forecast to become dominant in the capital, Copenhagen, from this week, and nationwide soon afterwards. In Norway, authorities said Omicron was “becoming established and will dominate” across the country before Christmas. Norwegian officials have warned Omicron could infect between 90,000 and 300,000 people a day within the next three weeks unless new measures proved effective, compared with a previous peak of about 1,000, while hospital admissions could reach twice their previous level. Norway has registered record numbers of infections and hospital admissions in recent days, among them 958 Omicron cases reported on Monday, including 472 in the capital, Oslo. The prime minister, Jonas Gahr Støre, warned of a serious situation. A combination of the still-dominant Delta variant and the fast-spreading Omicron would create “a total saturation of the national health system”, Støre said, announcing on Monday evening that booster shots were to be brought forward for health workers and all over-45s. The prime minister also announced that from Wednesday, bars and restaurants would no longer serve alcohol, remote working would be compulsory where possible, mask mandates would be extended and access to pools and gyms restricted. “There is no doubt, the new variant really changes the rules. That’s why we need to act fast and we need to act again,” Støre said. “For many this will feel like a lockdown, if not of society then of their lives and of their livelihoods.” Elsewhere in Europe, infection numbers in countries that endured significant waves last month, before Omicron emerged – including Austria, Germany, the Netherlands and Belgium, as well as central and eastern European nations such as Slovakia, the Czech Republic and Croatia – have fallen sharply. However, officials in France, where there are also signs that the pace of a rapid recent surge may be starting to slow, have warned Omicron will almost certainly fuel a sixth wave, while cases in countries in southern Europe that largely escaped the autumn wave are starting to rise rapidly. Martin Hirsch, the head of Paris’s AP-HP hospitals group, Europe’s largest hospital system, said on Monday France should prepare for an Omicron-driven wave of infections starting in January, while Belgium’s chief epidemiologist said he expected a fresh surge to start “around about new year’s time”. Despite steadily falling case numbers, the Dutch government was expected on Tuesday to announce schools would close a week early for Christmas as infections remained high and hospitals struggled with a wave of patients. Restaurants, bars, non-essential stores and other public places have been closed from 5pm to 5am in the Netherlands since late November in an attempt to slow the virus’s spread. Experts have said Denmark’s advanced sequencing capacity – the country has developed a quick genetic test for Omicron, and is screening every positive test for the variant – provides a uniquely comprehensive picture of how the variant is spreading, and should serve as a warning of what is to come elsewhere in Europe. Researchers at the Statens Serum Institute in Copenhagen estimated in a report this week that Omicron cases in Denmark were doubling every two days, with about three-quarters of infections reported in people who have received two vaccine doses. They predicted the variant would push daily infections to more than 10,000 by the end of this week, with numbers rising further and hospitals coming under pressure even if, as most scientists believe, Omicron is less virulent than earlier variants – but said their modelling did not account for the impact of booster shots.