The North American leaders are expected to discuss trade and the Buy American plan.
The pandemic has pushed as many as 8 million children into labour, research suggests.
The U.S. has made a "request for consultations" about Canada's tariff-rate quotas.
The East Asian giant is set to be the only G20 country to have a growing economy this year.
"Canada remains strong and united when faced with these illegal tariffs on aluminium exports," said Deputy Prime Minister Chrystia Freeland.
“Canada is doing the right things and the United States is wrong."
Immediate relief from U.S. duties is "unlikely," B.C.'s premier says.
Canada has a long history of helping the U.S. in times of crisis. Now the novel coronavirus has many claiming the U.S. government is turning its back on its strongest ally.
Health-care professionals wear the respirators to ward off COVID-19.
In 2018, Canada exported $2.7 billion worth of canola seed to China.