The US and France have reported their highest daily rises in new Covid cases since the pandemic began, as the Omicron variant continues to spread.
According to the US Centers for Disease and Prevention (CDC) the country reported more than 440,000 new infections on Monday.
However, officials said the numbers could be an "overestimate" due to reporting delays over Christmas.
France meanwhile reported Europe's highest ever number of new daily cases.
It saw 179,807 infections on Tuesday, with French health minister Olivier Véran earlier warning that "everything suggests" France could see as many as 250,000 daily cases by the start of January.
In the US however, a CDC spokesperson told news site Politico the figure was likely an "overestimate" due to lags in testing and test centre closures over the Christmas period, adding that case counts "will become more stable after the new year".
Italy, Greece, Portugal and England all also reported record rises on Tuesday.
It comes as the World Health Organization (WHO) warned that the risk of the Omicron variant "remains very high" in its weekly Covid update.
According to the update published on Tuesday, the number of new Covid infections of all strains grew by 57% in Europe in the week before 26 December, and by 30% in the Americas region.
Studies suggest the Omicron variant is milder than Delta, with a 30% to 70% lower chance of infected people ending up in hospital. But fears remain that the sheer number of cases stemming from the highly infectious variant could overwhelm hospitals.