The U.S. Centers for Disease Control and Prevention warns that anyone can be a coronavirus carrier even if they aren't showing any symptoms.
The CDC on Wednesday affirmed a study from Singapore that says 10 percent of new cases were spread by people who showed no signs of being sick. It said that even those who had the virus and appear to be recovered can still be contagious.
The agency says this study reinforces the need for social distancing.
The head of the CDC, Dr. Robert Redfield, warned in a radio interview Wednesday that there could be another wave of coronavirus in the late fall and that his agency is already preparing.
World Health Organization Director-General Tedros Adhanom Ghebreyesus forecast Wednesday that the number of confirmed cases will hit 1 million soon.
U.S. President Donald Trump said at his daily White House briefing Wednesday that the United States' national strategic stockpile of medical protection equipment is nearly depleted.
Also Wednesday, a Russian transport plane filled with protective gear and medical equipment landed in New York, not long after Trump and President Vladimir Putin chatted by telephone.
The official number of confirmed cases in Russia is about 2,300. But some Russian doctors suspect the real number is much higher.
With so much still unknown about the coronavirus and the general unease of not knowing what will happen next, the number of background checks for new gun owners reached an all-time high of 3.7 million in March, the FBI said Wednesday.
While gun rights advocates say Americans have a right to increase their safety and security in stressful times, those who favor gun control say they worry about weapons in the house when people are under lockdown and tense.
Florida has become the latest state to order a 30-day lockdown. The sight of college students crowding Florida beaches during spring break last month - many of whom said they don't care about the virus - angered many across the country.
Meanwhile, Italy has extended its nationwide lockdown for 30 more days and Japan has extended its entry ban to Africa and the Americas, bringing the number of countries whose citizens are denied entry to 73. All foreign visitors to Japan must enter a two-week quarantine.