Health authorities in Argentina, France, Italy, Sweden, Croatia and Turkey have registered more coronavirus infections in one day than ever before since the pandemic began.
Argentina's health ministry said 81,210 new cases were reported in 24 hours.
The South American country's previous record was 50,506 on December 30.
Argentina had reported its first case of the Omicron variant of the coronavirus in early December.
The new peak coincides with the summer holidays in the southern hemisphere, with thousands of people travelling around the country.
More than 70 per cent of Argentinians are fully vaccinated.
French Health Minister Olivier Veran told parliament on Wednesday that the country's latest COVID-19 new cases figure stood at around 335,000 new confirmed cases, marking a new record.
Italy also recorded a new daily high in coronavirus infections on Wednesday.
The health authorities reported more than 189,000 infections and about 230 virus deaths within one day.
Nearly 1.1 million tests were done during that time, with the proportion of positive test results at about 17 per cent.
The country's Council of Ministers is meeting on Wednesday evening and is expected to approve new measures to slow the spread of the disease.
Daily coronavirus cases in Sweden soared to a record high although numbers in intensive care remain well below previous pandemic peaks, the country's health agency said on Wednesday.
Case numbers have surged since November and in December the government tightened restrictions on public gatherings and urged citizens to work from home to help contain the spread.
Infections reached 17,320 on Tuesday, said Britta Bjorkholm, head of the health agency's department for disease control.
That was sharply up on the previous daily record of 11,507 registered on December 30,
"We have a rapid increase in the number of cases but so far not such a big impact on the healthcare system," she told a news conference.
In Croatia, officials said Omicron has fuelled the highest number of daily new infections since the start of the pandemic.
A total of 8587 new cases were confirmed in the past 24 hours in Croatia, which presents a 50 per cent rise since last week, Prime Minister Andrej Plenkovic said during a government session.
"The numbers show that Omicron is spreading, we know it is a highly contagious variant that is present here," he said.
"This is a warning how important it is to use everything at our disposal for protection from coronavirus."
Turkey recorded 66,467 new COVID-19 cases in the last 24 hours, the highest daily figure on record, health ministry data showed.
It also recorded 143 deaths over the coronavirus in the same period, the data showed.
Cases in Turkey have more than doubled in just over a week as the Omicron variant became dominant in the country.
"Despite the rise in infections due to the Omicron variant, there is no worrying rise in hospitalisation," Health Minister Fahrettin Koca said on Twitter.
with reporting from DPA and AP