Breaking News | Experts say coronavirus prevalence in US is high because the test is “too sensitive”

Today, there are 5.9 million COVID-19 cases in the United States, with more than 182,000 deaths.

On Thursday, the United States recorded 45,604 new coronavirus cases. If the contagious rates in Massachusetts and New York apply nationwide, that means that only about 4,500 people actually need to segregate contact tracking and participate.

As of Sunday, Johns Hopkins had a daily positive rate of 8.62% in the United States. The World Health Organization states that countries that have conducted extensive testing of COVID-19 should stay below 5% for at least 14 days before re-examination.

The researchers say the solution is a more extensive use of rapid testing with adjusted thresholds to focus on the most infectious people with COVID-19.

This proposal violates the testing guidelines recently updated by the White House Coronavirus Task Force.

Last Monday, the CDC changed its guidelines. It says that if exposed but asymptomatic, “unless you are a vulnerable individual, you don’t necessarily need a test,” or your doctor will advise you.

Previously, we recommended that you contact a person known to be infected with COVID-19 before undergoing testing.

“The decision not to test asymptomatic people is really the opposite. In fact, we need to intensify testing of different people, but we have to do it through completely different mechanisms,” Harvard said. Dr. Dr. Michael Mina, an epidemiologist at TH Chan Public Health School, told The Times.

“We’ve used one type of data for everything, it’s just a plus or a minus. That’s it. We use it for clinical diagnosis, public health, and policy making,” Mina said. It was

“I think it’s really irresponsible to give up the perception that this is a quantitative problem,” Mina added.

On Thursday, the Trump administration announced it would buy 150 million swift tests, but Mina said he needed to change the testing process.

The solution to today’s tests may be to adjust the cycle thresholds currently used to determine if a patient is infected with a lower number.

Most tests have a limit of 40 or 37. That is, COVID-19 is positive if the test requires up to 40 or 37 cycles for detection.

The test thresholds are so high that they detect people who are infected with a live virus or who have few remnants of the infection and few gene fragments that don’t pose a risk, Mina said. It’s like finding hair in a room after a person leaves.

According to experts, Juliet Morrison, a virologist at the University of California at Riverside, experts say the appropriate cutoff for the virus is 30 or 35 cycles.

Mina said he would set the cutoff to 30.

Wadsworth, a state research institute in New York, analyzed cycle thresholds for COVID-19 PCR tests that had already been processed and found in July that 794 positive tests were based on the 40 cycle threshold.

At a cutoff of 35, about half of these tests will no longer be considered positive. If the cycle is limited to 30, about 70% will no longer be considered positive.

In Massachusetts, 85-90% of people who had a positive circulating threshold of 40 in July were considered negative at 30 cycles, according to Mina.

“I would say that none of those people should be contact tracked, not one,” he said.

The Food and Drug Administration has not specified a range of cycle thresholds that will be used to determine who is positive, “it is privately set by private manufacturers and laboratories,” he said.

The Centers for Disease Control and Prevention said it is considering using cycle threshold measurements for “policy making”.

The CDC’s own calculations suggest that it is very difficult to detect live virus in samples that exceed the 33-cycle threshold.

“The lack of people recording CT values ​​for all of these tests is truly inspiring,” said Angela Rasmussen, a virologist at Columbia University in New York.

“It will be useful information to know if someone is positive, whether the viral load is high or low,” she added.

The FDA pointed out that newer infections may have a lower viral load, and less sensitive tests may miss these infections.

Mina says if so, those people can be tried again.

People infected with COVID-19 are most infectious 1-2 days before symptoms appear, and become infected about 5 days later.

Virology experts say that you need a test that’s fast, cheap, and rich enough to frequently test everyone who needs it, even if the test is less sensitive.

“It may not catch the last one of the infected, but it will surely catch the most infectious people, including the Super Spreader. That alone will virtually eliminate the epidemic,” Mina said. Said.