Cases of COVID-19 have increased in Sweden's main cities with the more contagious Delta having emerged as the dominant variant in the country, health authorities said on Friday, though it added infection levels nationally remained low. Sweden reported 1,855 new cases of COVID-19 last week, a 24% increase compared to the previous week. "The number of cases nationally of Covid-19 continues to be at a low level, but an increase is seen in all metropolitan regions," the authority said in a statement, adding that 75% of Sweden's adult population had now received at least one dose of vaccine.