[The stream is slated to start at 11 a.m. ET. Please refresh the page if you do not see a player above at that time.]The World Health Organization is holding a briefing Monday on the coronavirus as the pandemic in the United States and Europe accelerates.On Saturday, British Prime Minister Boris Johnson announced a second national lockdown in England as coronavirus cases surge there.Last week, the WHO said some countries may need to shut down their nonessential businesses again as a way to take the “heat” out of their worsening coronavirus outbreaks.WHO officials said they are still hopeful most countries won’t need to impose nationwide lockdowns, which were imposed by some world leaders earlier in the year as a way to slow the spread of the virus. But as Covid-19 cases now accelerate across the Northern Hemisphere, particularly in the United States and Europe, some countries may need to impose those stricter mitigation measures again, the agency said.Separately, WHO Director-General Tedros Adhanom Ghebreyesus tweeted late Sunday that he has been quarantined after someone he was in contact with tested positive for the virus.Read CNBC’s live updates to see the latest news on the Covid -19 outbreak.