The World Health Organization's European office has warned of a "challenging" autumn and winter amid a summer surge of Covid-19 cases and reduced surveillance among member states.
The warning was accompanied by a call from the health body for countries to "urgently address gaps in pandemic monitoring and response to avoid preventable deaths and severe disruptions".
"At this time last year, I spoke to you about a new wave of Covid-19 sweeping across the region, driven by the Delta variant amid the lifting of restrictions and increased social mixing," WHO regional director for Europe Hans Kluge said in a statement.
"It's now abundantly clear we're in a similar situation to last summer - only this time the ongoing Covid-19 wave is being propelled by sub-lineages of the Omicron variant," he added.
The rapid increase in cases coupled with "reduced virus surveillance" prompted the organisation to "forecast a challenging autumn and winter in the European Region".
It also prompted the release of a Covid-19 strategy for autumn and winter, "to help prepare for the coming waves of infection".
"Waiting for the autumn to act will be too late," Kluge said.
The strategy pushes increased vaccine uptake in the general population, a second booster dose for immuno-compromised people, a possible second booster to specific at-risk groups, and the use of face masks indoors and on public transportation.
Kluge said the number of new infections in the WHO's European area - 53 countries and regions including several in Central Asia - had tripled in the last six weeks.
The region recorded 2,585,734 cases over the last seven days.
The organisation noted that while hospitalisation rates had doubled in the same period, admissions to intensive care units (ICU) had "so far remained relatively low".
"However, as infection rates in older groups continue to rise, Europe is still seeing close to 3,000 people die of Covid-19 every week," Kluge stressed.
Last week, WHO Europe recommended a second booster shot of a Covid vaccine for people over 60 years old.