The US government’s top infectious diseases expert has warned that daily COVID-19 cases could more than double if Americans fail to take counter-measures.
Anthony Fauci, the head of the US National Institute of Allergy and Infectious Diseases, also cautioned against pinning hopes on a vaccine.
California, Texas and other states are reporting record increases in cases of the sometimes deadly illness caused by the coronavirus.
Unless Americans wore masks and recommitted to social distancing, the daily increase in new cases nationwide, currently about 40,000, could reach 100,000, Mr Fauci told a US Senate committee.
“Clearly we are not in total control right now,” Mr Fauci said on Tuesday (local time).
“I am very concerned because it could get very bad.”
Mr Fauci said “there is no guarantee” that ongoing efforts will produce a safe and effective vaccine to prevent infection by the virus, pouring cold water on hopes for a quick fix to the health crisis.
Many countries in Asia and Europe have controlled the pandemic with strong, co-ordinated government responses marked by stringent lockdowns and mandatory mask-wearing in public.
In the US, wearing masks has become a divisive political issue, and many southern and western states began reopening businesses without having met government health benchmarks for doing so safely.
With the virus on the rise in most US states, the EU has excluded the US from its initial “safe list” of countries from which the bloc will allow non-essential travel beginning on Wednesday
COVID-19 cases more than doubled in June in at least 10 states, including Texas and Florida, a Reuters tally showed.
In parts of Texas and Arizona, hospital intensive care beds for COVID-19 patients are in short supply.
More than 126,000 Americans have died from COVID-19 and millions have lost their jobs, as businesses and schools shut to curtail the virus.
The economy contracted sharply in the first quarter and is expected to crater in the April-June period.
Democratic presidential candidate Joe Biden on Tuesday launched a fresh attack on US President Donald Trump’s “historic mismanagement” of the pandemic.
Biden argued Trump could have saved lives and the economy by acting earlier to control the virus.
“It didn’t have to be this way,” the former vice president said in a speech in Delaware, in which he unveiled an updated plan to tackle the pandemic.
Biden’s plan includes more testing and hiring at least 100,000 contract tracers.
“Donald Trump failed us,” the former vice-president said.
In the past few days California, Texas and Florida have all moved to close bars, which public health officials have warned are among the riskiest non-essential businesses and likely one of the larger contributors to the recent spikes.
On Tuesday, New York, New Jersey and Connecticut added California and seven other states to a list of those from which visitors must self-quarantine for 14 days upon arrival.
Texas and Florida were on the original list announced last week.
South Carolina has also emerged as a hotspot, reporting a record single-day increase of 1755 cases on Tuesday.