A Covid patient breathes oxygen through a mask at the sub-intensive care unit of the Casalpalocco hospital, south of Rome, on October 13, 2021.Alberto Pizzoli | AFP | Getty ImagesCovid cases in Europe have increased for the third consecutive week, World Health Organization officials said at a briefing Wednesday, urging caution as temperatures fall and work, travel and leisure activities return to normal.Europe is the only area out of the WHO’s six regions of member states where cases are climbing, researchers wrote in an epidemiological update published Tuesday. There were more than 1.3 million Covid cases reported across the continent over the week ended Sunday, a 7% jump from the prior seven days.”That’s three weeks of progressive increase,” Dr. Mike Ryan, executive director of the WHO’s health emergencies program, said during a Q&A streamed on the organization’s social media channels. “So while the overall global curve looks like it’s tracking down, Europe has gone up three weeks in a row.”The situation in Europe is being partially driven by surges in Czechia, Hungary and Poland, where Ryan said Covid cases jumped 50% over the last week. With winter approaching, Ryan said Covid’s already starting to weigh heavily on health-care systems in some countries, limiting the availability of intensive care beds.Ryan blamed the surge, at least in part, on the easing of Covid restrictions.”The Northern hemisphere is heading into another winter, and just need to be a little concerned about that uptick across Europe as we enter the late, late, deep autumn,” Ryan said. “And as societies are opening up, we’re seeing those numbers rise, and in a number of countries, we’re already seeing the health system begin to come under pressure, we’re seeing the number of available ICU beds decreasing.”And as people prepare to travel and meet in person for the holiday season, Ryan called for unvaccinated individuals to get immunized against the virus in hopes of preventing Covid outbreaks in the months ahead.”There’s good news in the sense that we’re not seeing this massive increase, but it’s still concerning even in the context of relatively high levels of vaccination,” he said.In addition to the highly transmissible delta variant, which fueled global Covid spikes over the summer, researchers are now monitoring an evolution of the strain that could be even more dangerous. Known as delta plus, experts in the U.K. are seeing the mutation in a growing number of Covid patients.But there’s currently no proof that delta plus is more contagious than its predecessor, Prime Minister Boris Johnson’s spokesman said Tuesday.And amid a surge in Covid cases and deaths, Russian President Vladimir Putin is requiring most workers to stay home for one week beginning Oct. 30, according to the Associated Press. Russia reported a seven-day average of nearly 31,700 new Covid cases as of Tuesday, up from more than 27,200 a week prior, according to data compiled by Johns Hopkins University.