Aug 20 (Reuters) - The Federal Reserve Bank of Kansas City"s annual economic symposium in Jackson Hole, Wyoming, will take place on Aug. 27 virtually and not in person as planned, the clearest signal yet of the central bank"s increasing worries about the impact of the COVID-19 Delta variant. "While we are disappointed that health conditions will prevent us from being able to gather in person at the Jackson Lake Lodge this year as we had planned, the safety of our guests and the Teton County community is our priority," said Kansas City Fed President Esther George in a statement, citing the recently elevated COVID-19 health risk level in Teton County. The reversal raises questions about the Fed"s broader assessment of the Delta variant"s economic impact, which Fed Chair Jerome Powell and other policymakers have mostly played down, saying that businesses and households have learned to live with the virus. The gathering was already going to be a muted affair. The guest list had been scaled back, with foreign central bankers not attending, many of the lodge facilities closed or limited, and masks mandatory outside of meals. Vaccines were required for all attendees and their families. But this week the Fed said that Powell would give his marquee speech on the economic outlook remotely. And now everyone else will attend online as well. Sparsely populated Wyoming on a per capita basis has averaged 54 cases per 100,000 people in the last week versus 43 per 100,000 for the country as a whole. Teton County where the conference was to take place has an even higher rate of 62 per 100,000.