As coronavirus cases surge across the country, President Donald Trump continues to blame increased testing despite mounting evidence that the virus is spreading widely throughout some communities.
At the beginning of the U.S. outbreak, public health specialists criticized the country's capacity to conduct widespread diagnostic testing as far too little. The country has ramped up testing capacity to more than an average of 478,000 tests per day in June, compared with an average of over 345,000 per day in May.
"Cases are going up in the U.S. because we are testing far more than any other country, and ever expanding," Trump tweeted Tuesday. "With smaller testing we would show fewer cases!"
However, public health specialists have repeatedly said the data does not indicate that increased testing accounts for the recent surge in daily new cases. To dispel claims that testing is to blame for the country's growing outbreak, epidemiologists point to a figure known as the positivity rate, which indicates the percent of tests that come back positive in a given region.
The data point is important because it indicates how broadly the virus is spreading throughout the community. The World Health Organization has previously said that the positivity rate for a country should remain stable at about 5% for 14 days before a country eases restrictions.
Throughout June so far, the U.S. positivity rate has hovered around 5%, according to data compiled by Johns Hopkins University, though the seven-day average has ticked up in recent days. Some epidemiologists have noted that the fact that the national postivity rate has yet to drop despite increased testing of the population could indicate that the virus is spreading.
When broken down by states, the U.S. paints a more worrying picture. Nineteen states currently have a positivity rate above 5% over the past seven days, according to Johns Hopkins data, and that includes Arizona, which reports that 21.15% of all tests are coming back positive, and Florida with a positivity rate of 12.22%.
"That states are finding more cases relative to the amount of tests they are conducting provides the strongest rebuttal to the administration's assertion that case numbers are rising because we're getting better at finding cases through increased testing," Jennifer Nuzzo, lead epidemiologist of Johns Hopkins University's Covid-19 Testing Insights Initiative, wrote in an op-ed for The Washington Post. "They tell us the opposite — that each of these states needs to do even more testing to find infections — followed by more rigorous contact tracing and isolation."
Recent spikes in some states such as Florida have prompted state officials to acknowledge that the increase in new cases is not solely attributable to more testing.
"Even with the testing increasing or being flat, the number of people testing positive is accelerating faster than that," Florida Gov. Ron DeSantis, a Republican, told reporters last week. "You know that's evidence that there's transmission within those communities."
Most of those who test positive are now young people who "aren't sick," Trump told reporters later Tuesday. He added that the U.S., which has the largest coronavirus outbreak in the world, has conducted by far more tests than any other country.
"By having more cases, it sounds bad. But actually what it is, is we're finding people," he said. "But just remember, the reason we have more cases than other countries is that our testing is so much."
A greater share of the people who test positive for the coronavirus are in fact younger, but Dr. Anthony Fauci, the nation's top infectious disease expert, told Axios on Monday that more young people testing positive could still be worrisome.
"They get infected first, then they come home, and then they infect the older people. The older people get the complications, and then they go to the hospitals," Fauci said. "The death rate always lags several weeks behind the infection rate."
Trump drew the ire of epidemiologists and some politicians on Saturday when he told a crowd at his campaign rally in Tulsa, Oklahoma, that he had told officials to "slow the testing down, please" because the U.S. was identifying too many new cases. Administration officials said the comment was made in jest and that the president has never directed officials to slow testing.
Trump's testing remarks come as states like Arizona, Texas, Florida and others particularly across the American South and West have ballooning outbreaks underway, former Food and Drug Administration commissioner Dr. Scott Gottlieb told CNBC on Monday. Gottlieb added that more severe interventions might be necessary soon to stop pervasive spread in some parts of those states.
"They're having major outbreaks underway. There's no question about it," he said. "They might be past the point that they can control this just with simple interventions like trying to get more people to wear masks and people being mindful of their social interactions."
Disclosure: Scott Gottlieb is a CNBC contributor and is a member of the boards of Pfizer, genetic-testing start-up Tempus and biotech company Illumina.