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German researchers say the United States is only detecting 1.6% of novel coronavirus cases, suggesting there may already be some 26 million infections nationally, 1 million in Florida and several tens of millions worldwide.

In a way, a potentially much higher denominator portends good news of much lower death rates than previously feared. But because of delayed or insufficient testing, the German researchers also conclude that current case counts aren’t very useful information, especially in the U.S., Italy, Spain and the United Kingdom, where response to COVID-19 outbreaks has been slower. So they call for urgent improvement in detecting new infections to contain the virus and prevent second and subsequent "waves" of spread.

“These results mean that governments and policy-makers need to exercise extreme caution when interpreting case numbers for planning purposes," Sebastian Vollmer, professor of development economics at the University of Göttingen, said in a prepared statement.

The study by Vollmer and Christian Bommer, another economist at Göttingen University, which is not peer reviewed, analyzes data from a separate study published recently in The Lancet Infectious Diseases.

Their findings come in the wake of researchers at the University of Washington this week vastly reducing their prediction of deaths and hospital bed shortages in Florida and elsewhere, after an influx of new data.

The German study also comes on the heels of the National Academies of Sciences, Engineering and Medicine dashing hopes that warm, humid summer weather might slow spread of the new virus. The panel sent a report to the White House recently, saying current research does not support that hypothesis.

In their study, Vollmer and Bommer used estimates of COVID-19 mortality and time until death to test the quality of official coronavirus case records. They found that countries have only discovered on average about 6% of coronavirus infections. The U.S. detected only 1.6% of COVID-19 infections detected, and the United Kingdom only 1.2%.

The researchers say insufficient testing and resulting failure to contain the virus may explain why some European countries are suffering much higher COVID-19 casualty numbers than Germany, which detected an estimated 15.6% of infections compared with only 1.7% in Spain and 3.5% in Italy. South Korea detected almost half of its infections.

The researchers estimate that on March 31, the U.S. had more than 10 million coronavirus infections, Spain had more than 5 million, Italy around 3 million and the UK about 2 million. On the same day Johns Hopkins University's interactive online map displayed less than 900,000 confirmed cases globally, meaning the vast majority of infections went undetected.

As of Thursday afternoon (April 8), Florida Department of Health reported 16,364 coronavirus cases and 354 deaths. That included 106 cases in Brevard and two deaths. But if the German researchers' premise that only 1.6% of U.S. cases are being detected holds true for Florida and Brevard, the state could already have some 1 million infections and the county in excess of 6,600.

Case death rates ranged from 1.1% in Germany to 11.7% in Italy, the German researchers note, suggesting vast differences in the quality of countries’ case records. So confirmed fatality rates may be "a very poor proxy for the true infection fatality rate if a high number of infections remain undetected," the researchers wrote.

"Despite such uncertainties, policy makers rely heavily on the extrapolation of past trends when planning responses to the pandemic," the researchers said.

Vollmer and Bommer used the reported infection fatality rates in Wuhan, China, as a benchmark for other countries and calculated infection fatality rates for the 40 most affected countries using United Nations population data to correct for differences in age distributions. Because people returning to Wuhan have been subject to extensive testing, the researchers said "substantial underdiagnosing is unlikely, providing confidence in these numbers."

In all countries, the number of confirmed cases by March 17 was substantially lower than what would have been expected given the number of deaths reported two weeks later.

Ending travel restrictions and social distancing will require a strong reduction in transmission of new cases but also major improvements in nations' abilities to detect new infections so they can isolate infected patients and trace who they've come in contact with, the researchers said.

"In absence of such measures, the virus might remain undetected again for an extended period of time and a new outbreak is likely just a matter of time," the researchers wrote.

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Jim Waymer is environment reporter at FLORIDA TODAY.

Contact Waymer at 321-242-3663

or jwaymer@floridatoday.com.

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