The Centers for Disease Control (CDC) in the US says the number of COVID-19 patients may be 10 times higher than reported figures.
Robert Redfield, director of the CDC, made this known during a call with journalists, on Thursday.
He attributed this to the restriction to testing only symptomatic persons, as asymptomatic carriers are not tested.
The US has recorded over 2.5 million cases, according to a website which provides real-time update on the disease situation globally.
Although, over one million patients have recovered from the infection, the country has recorded more than 126,000 deaths.
Redfield said there are increasing concerns as the US witnesses a spike in cases.
He said the country is in a different situation when compared to the previous months of April and May.
“Our best estimate right now is that for every case that’s reported, there actually are 10 other infections,” he said.
“This virus causes so much asymptomatic infection. The traditional approach of looking for symptomatic illness and diagnosing it obviously underestimates the total amount of infections.
“It is clear that many individuals in this nation are still susceptible. This is still serious. But I am asking people to recognize that we are in a different situation today than we were in March or April.
“We probably recognized about 10% of the outbreak by the methods that we use to diagnosis between the March, April and May.
“As we go into the fall, in the winter, these are going to be really, really important defence mechanisms.”
Redfield said between 5% and 8% of the US population have been exposed to the disease, and he asked residents to comply with the CDC directives.
On Thursday, 39,327 new COVID-19 cases were reported by state health departments across the US.
This figure surpasses the previous single-day record of 38,115, which was set on Wednesday.
Texas, Alabama, Missouri, Nevada, and New Jersey are reporting more cases.
Texas confirmed 5,996 new cases on Thursday, with 47 new deaths.
The spike in cases and the running out of bed spaces at intensive care units (ICU) prompted Greg Abbott, governor of Texas, to call a temporary halt to the reopening of economy.
Abbott also suspended elective surgeries at hospitals in some parts of the state to free up bed spaces.
“This temporary pause will help our state corral the spread until we can safely enter the next phase of opening our state for business,” he said.
New York, New Jersey and Connecticut said they will ask people travelling from eight states Alabama, Arkansas, Arizona, Florida, North Carolina, South Carolina, Texas and Utah to go into self-isolation for 14 days.