Bill Gates, who has been warning for years of a global disease outbreak, said that while many countries have coordinated testing on a national level during the coronavirus pandemic, the United States has not, and access to tests is "chaotic."
Gates also said in his interview with Savannah Guthrie that aired on the "TODAY" show Friday that he has recently seen evidence that a hoped-for timeline of 18 to 24 months for a coronavirus vaccine may come to pass.
"Usually a vaccine takes over five years because you have many steps," including first testing in animals, then with humans on small, medium and large scales. But with the coronavirus pandemic, "because of all the incredibly negative effects, the sooner the better."
Download the NBC News app for full coverage of the coronavirus outbreak
"The best scientists [are] working hard on this," Gates said. "In fact, in the last few weeks I've seen signs that we may get to the optimistic side of that time projection" for a vaccine.
Gates in 2015 warned that "if anything kills over 10 million people in the next few decades, it's most likely to be a highly infectious virus rather than a war."
On Friday, he called the coronavirus crisis "a nightmare," saying that "the human-to-human respiratory spread is the scariest scenario."
"I wish it had come, you know, five or 10 years later, then governments might have done the preparation to move quickly, like a few governments did," Gates said.
"Many countries decided that at the national level, they would orchestrate the testing" for the virus, he said. "That hasn't happened in the United States. It might not happen. But, you know, the access to tests is just, you know, chaotic."
Medical experts say mass testing is key before the U.S. can reopen.
Asked what he thinks about moves toward reopening by some states such as Georgia, Gates said he is "afraid we'll have some people and some states that move too quickly and have to back off."
"It's going to be awhile before things go back to normal," Gates said. "I wish I could say that we're halfway through, but I don't think so."