There is "no guarantee" that the United States will have an effective coronavirus vaccine by the start of next year, the country's top infectious disease expert said on Tuesday.
"[But scientists] are cautiously optimistic that we will know the extent of efficacy" by that time, Anthony Fauci testified to Congress.
Fauci also said he was concerned by the rise in infections seen in more than half of US states, including Arizona, Florida and Texas. He said there was a worrying "all-or-none phenomenon," whereby states were either fully locked down or reopened quickly only to see people crowding in bars and flouting all public health recommendations.
 Many of the states seeing upticks in virus cases had less stringent lockdown measures or moved to reopen quickly, and are now slowing or reversing plans to restart the economy. In Arizona, where daily coronavirus-related deaths have increased, Governor Doug Ducey on Monday reinstated shutdown orders for bars, gyms and theatres. Bars have been shuttered again in Texas and Florida, where beaches have also closed for the upcoming Independence Day holiday weekend.
Republican Senator Lamar Alexander called on President Donald Trump to "occasionally wear a mask" to eliminate the political stigma around doing so. "The president has plenty of admirers," he said in opening the hearing. "They would follow his lead, it would help end this political debate. The stakes are too high for this political debate about pro-Trump, anti-Trump to continue."
Related Story