COPENHAGEN : The World Health Organization on Thursday urged Europeans to travel responsibly during the summer holiday season and warned the continent was "by no means out of danger" in the battle against COVID-19 despite a steady decline of infection rates in recent weeks."With increasing social gatherings, greater population mobility, and large festivals and sports tournaments taking place in the coming days and weeks, WHO Europe calls for caution," the WHO's European head Hans Kluge told a press briefing."If you choose to travel, do it responsibly.