Factbox: Key issues as Tokyo marks 100 days until Olympics

National Stadium, the main stadium of Tokyo 2020 Olympics and Paralympics, is pictured in Tokyo, Japan, March 18, 2021. Picture taken on March 18, 2021. REUTERS/Kim Kyung-Hoon

TOKYO (Reuters) - The countdown to the Tokyo Olympics hit the 100-day mark on Wednesday as the Games draw closer to reality after a one-year delay due to the COVID-19 pandemic.

But several questions remain unanswered amid uncertainties over the pandemic, including how many spectators will be allowed into venues and what revisions will be made to participants' COVID-19 health protocols.