The World Health Assembly is the decision-making body of the World Health Organization.
Attended by delegations from all WHO member states, the annual meeting determines WHO policies, reviews its budget, and most importantly, discusses a specific health agenda set by the Executive Board.
For this year, the topic is, unsurprisingly, the global COVID-19 pandemic.
Speaking to President Moon over the phone in early April, WHO Director-General Tedros Adhanom asked President Moon to be the keynote speaker for this year's World Health Assembly.
He praised Seoul's COVID-19 response and stressed that it's important for Moon to share South Korea's experience in tackling COVID-19 and encourage a comprehensive approach to deal with the outbreak.
It's the first time that a sitting South Korean President will deliver a keynote speech at the World Health Assembly.
President Kim Dae-jung spoke at the venue in 2004, but that was as a former president.
President Moon's keynote speech at the WHA is a good opportunity for South Korea to promote its so-called "K-Quarantine" model.
It's based on swift and aggressive testing, detailed contact tracing, quarantine and treatment.
Seoul hopes to make it a new international standard that can be used by other countries when dealing with epidemics.
Oh Jung-hee, Arirang News.