Restaurants, bars and beaches in the world's worst-hit nation closed from California to Florida, as states reeling from yet another surge.
The virus emerged at least six months ago in China, where the WHO will send a team next week in the search for its origin, Tedros Adhanom Ghebreyesus said.
The legislation was unanimously approved by China's rubber-stamp parliament on Tuesday morning.
The reminder that the pandemic -- which has claimed more than 480,000 lives around the world -- is far from over came amid more grim news.
Duke and Duchess of Sussex are having meetings with Oprah Winfrey and community leaders to be updated about Black Lives Matter movement and how she can help.
US Secretary of State Mike Pompeo will hold talks with senior Chinese foreign policy official Yang Jiechi at Hawaii on Wednesday.
North Korea's harshest criticism of Washington came on Friday, and casts doubt over the future of the two sides' long-stalled nuclear talks process.
The optimism on trading floors was shattered when Federal Reserve boss Jerome Powell signalled the world's top economy would take some time to bounce back.
The threat comes just a day before the two-year anniversary of the landmark summit in Singapore where Kim Jong Un shook hands with Donald Trump.
The UK government also intends to reopen all stores on June 15.
The US action, which takes effect June 16 but could be implemented sooner if President Donald Trump orders it.
Violent clashes erupted repeatedly in a small park next to the White House, with authorities using tear gas, pepper spray and flash bang grenades.
The letter addressed to Boris Johnson was signed by Malcolm Rifkind, Margaret Beckett, William Hague, Jeremy Hunt, David Miliband, David Owen and Jack Straw.
Minneapolis, the epicenter of the unrest, was gripped by a fifth consecutive night of violence on Saturday.
Despite the threat of another trade war, investors are focusing on the easing of lockdowns around the world.
Confirmed US deaths stood at 100,396 late Wednesday, with nearly 1.7 million infections, according to the tally compiled by Johns Hopkins University.
The US announced sanctions against a Chinese government institute and eight companies for human rights violations.
Brazil has now recorded more than 310,000 cases, with experts saying a lack of testing means the real figures are probably much higher.
Under the notifications system, someone exposed to a person who tests positive for COVID-19 will receive an alert on their phone.
The world's longest international frontier at 8,900 kms (5,500 miles) was closed to travellers on March 21, but trade in goods has continued.
The downbeat mood was compounded by another spike in US jobless claims and overshadowed news several countries were easing strict lockdown measures.
Trump earlier this week ruled out renegotiating the partial trade deal inked in January, when asked about reports that China was looking to reopen talks.