EUGENE: Four more members of Japan’s World Athletics Championships team have tested positive for Covid-19, bringing the number of infections to 15, the Japan Association of Athletics Federations said Tuesday.The outbreak began over the weekend, when seven positive tests were announced among the camp, including two marathon runners, four support staff and the head coach.Another four positive tests were announced yesterday, involving one marathon runner and three more coaches, and on Tuesday JAAF said three more athletes and an official were hit by infections.One of those, the 200-metre sprinter Yuki Koike, will now have to miss his preliminary race, the federation said.All of those who have tested positive will observe a five-day isolation period.The outbreak comes during a surge of infections across the United States as new variants of Covid-19 take hold.The US Centers for Disease Control and Prevention said last week that 21 of Oregon’s 36 counties were deemed to be at “high” risk of the virus.On Saturday, British athlete Morgan Lake announced she had been forced to withdraw from the World Championships after testing positive for Covid-19.