When Kansas issued a mask mandate, 81 counties opted out. Researchers found coronavirus infection rates rose sharply in the opt-out counties, while falling in those that required masks.
Newsom said on Twitter that his children came into contact with a California Highway Patrol officer who tested positive for the virus. He said everyone in his family has tested negative so far.
Pharmaceutical company AstraZeneca made the announcement on Monday, saying that one dosing regimen showed the vaccine was 90% effective in preventing infection.
Previous spikes in South Korea were linked to outbreaks at churches and protests. Health officials say the current wave appears to have no links to any major groups or events.
Congress saw its first two members enter self-quarantine on March 8. Later that month, seven members tested positive or were presumed so and dozens more were quarantined. The ranks have since grown.
A map of confirmed COVID-19 cases and deaths around the world. The respiratory disease has spread rapidly across six continents and has killed at least 1 million globally.
View NPR's maps and graphics to see where COVID-19 is hitting hardest in the U.S., which state outbreaks are growing and which are leveling off.
In Kansas City, hospitals are treating local COVID-19 patients as well as patients transferred from rural counties in Missouri and Kansas, where there's no mandate or culture for wearing masks.
At a virtual meeting of the G20, the German chancellor said she was worried about vaccine availability.
As COVID-19 cases continue to soar across the country, officials are pleading with the public to rethink large holiday gatherings to mitigate the spread.
The experimental cocktail from the biotech company Regeneron is the same drug President Trump got when he was battling the coronavirus this year. It is designed for mild to moderate cases.
As COVID-19 hospitalizations surge, new data released by the federal government show how many hospitals are struggling with staffing.
On Friday alone, there were 195,000 new confirmed cases of the virus and 1,878 deaths. The U.S. has been adding 1 million cases every six days.
The arrangement, originally slated to begin Sunday, would have provided some travelers the ability to bypass a 14-day quarantine period. But new cases in Hong Kong have put the plan on hold.
The president's son, who announced his diagnosis on Instagram, said he has no symptoms and feels fine. Trump Jr. said he plans to quarantine and "take it seriously."