On 13 May 2008, Anderson suffered a severe asthma attack which required a stay in hospital. According to Yes' website, he was later "at home and resting comfortably." Yes' planned summer 2008 tour was subsequently cancelled, with the press release saying, "Jon Anderson was admitted to the hospital last month after suffering a severe asthma attack. He was diagnosed with acute respiratory failure and was told by doctors to rest and not work for a period of at least six months." Further health problems continued through 2008, resulting in Yes permanently replacing Anderson with vocalists Benoit David (2009–2012) and Jon Davison (2012–present). In September 2008, Anderson wrote that he's "so much better...so grateful and so blessed...I look forward to 2009 for the "Great Work" to come." He started singing again in early 2009. In 2009, he returned to touring (solo), performed along with Peter Machajdík and an ensemble of Slovakian musicians on Tribute To Freedom, an event to commemorate the fall of the Iron Curtain in former Czechoslovakia at Devin Castle near Bratislava, Slovakia, and continued touring in 2010 and the autumn of 2011, with Rick Wakeman for a UK tour (2010) and the eastern US (2011).