Comment by Riaz Haq on September 19, 2020 at 12:33pm

Your #Coronavirus Test Is Positive. Maybe It Shouldn’t Be. In 3 sets of data in #Massachusetts , #NewYork and #Nevada , up to 90% of people testing positive for #COVID19 carried barely any virus. Low virus load may not be contagious.- The New York Times

https://www.nytimes.com/2020/08/29/health/coronavirus-testing.html

Some of the nation’s leading public health experts are raising a new concern in the endless debate over coronavirus testing in the United States: The standard tests are diagnosing huge numbers of people who may be carrying relatively insignificant amounts of the virus.

Most of these people are not likely to be contagious, and identifying them may contribute to bottlenecks that prevent those who are contagious from being found in time. But researchers say the solution is not to test less, or to skip testing people without symptoms, as recently suggested by the Centers for Disease Control and Prevention.

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In three sets of testing data that include cycle thresholds, compiled by officials in Massachusetts, New York and Nevada, up to 90 percent of people testing positive carried barely any virus, a review by The Times found.

On Thursday, the United States recorded 45,604 new coronavirus cases, according to a database maintained by The Times. If the rates of contagiousness in Massachusetts and New York were to apply nationwide, then perhaps only 4,500 of those people may actually need to isolate and submit to contact tracing.

One solution would be to adjust the cycle threshold used now to decide that a patient is infected. Most tests set the limit at 40, a few at 37. This means that you are positive for the coronavirus if the test process required up to 40 cycles, or 37, to detect the virus.

Tests with thresholds so high may detect not just live virus but also genetic fragments, leftovers from infection that pose no particular risk — akin to finding a hair in a room long after a person has left, Dr. Mina said.

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Instead, new data underscore the need for more widespread use of rapid tests, even if they are less sensitive.

“The decision not to test asymptomatic people is just really backward,” said Dr. Michael Mina, an epidemiologist at the Harvard T.H. Chan School of Public Health, referring to the C.D.C. recommendation.

“In fact, we should be ramping up testing of all different people,” he said, “but we have to do it through whole different mechanisms.”

In what may be a step in this direction, the Trump administration announced on Thursday that it would purchase 150 million rapid tests.

The most widely used diagnostic test for the new coronavirus, called a PCR test, provides a simple yes-no answer to the question of whether a patient is infected.

But similar PCR tests for other viruses do offer some sense of how contagious an infected patient may be: The results may include a rough estimate of the amount of virus in the patient’s body.

“We’ve been using one type of data for everything, and that is just plus or minus — that’s all,” Dr. Mina said. “We’re using that for clinical diagnostics, for public health, for policy decision-making.”


But yes-no isn’t good enough, he added. It’s the amount of virus that should dictate the infected patient’s next steps. “It’s really irresponsible, I think, to forgo the recognition that this is a quantitative issue,” Dr. Mina said.

Comment by Riaz Haq on September 19, 2020 at 1:08pm

#US #CDC director says face #masks may offer more protection against #COVID19 than a #vaccine. Dr. Redfield: "And I will continue to appeal for all Americans, all individuals in our country, to embrace these face coverings." #coronavirus https://www.cbsnews.com/news/covid-face-mask-protection-vaccine-cdc... via @CBSHealth

Dr. Robert Redfield, the director of the Centers for Disease Control and Prevention, said during his testimony before a Senate subcommittee on Wednesday that wearing face masks may be more effective at protecting against COVID-19 than a vaccine.


Lawmakers asked Redfield and other top health officials about the government's response to the coronavirus pandemic, and he was questioned about the CDC's recommendation that people wear masks — a practice President Trump has often dismissed.

"I'm not going to comment directly about the president, but I am going to comment as the CDC director that face masks, these face masks, are the most important powerful public health tool we have," Redfield said. "And I will continue to appeal for all Americans, all individuals in our country, to embrace these face coverings."

Redfield said if Americans wore face masks for several weeks, "we would bring this pandemic under control," because there is scientific evidence they work and they are our "best defense."

"I might even go so far as to say that this face mask is more guaranteed to protect me against COVID than when I take a COVID vaccine, because it may be 70%. And if I don't get an immune response, the vaccine is not going to protect me," Redfield said. "This face mask will."

Several experts contacted by CBS News agree with that assessment: Since vaccines do not guarantee an immune response, masks may be more effective at preventing COVID-19. The FDA has previously said it would approve a coronavirus vaccine that was at least 50% effective. While that could significantly reduce the number of hospitalizations and deaths, it would not completely eliminate the disease or guarantee protection.

George Rutherford, a professor of epidemiology and biostatistics and director of the Prevention and Public Health Group at UC San Francisco, said the CDC director is "completely right."

"The good thing about a vaccine is you don't need to remember to put it on every day," Dr. Rutherford told CBS News on Friday. "The bad thing is, it's probably not going to work nearly as well as masks."

"Let's say masks are 95% effective — and who knows what the vaccine is going to be, but say it's 80% effective — in that sense, masks could be better than vaccines," he continued. "I don't think we know yet, but for right now, it's the total name of the game. It's the most effective thing we have."

Rutherford said a large proportion of the population — about 60 or 70% — would need to get vaccinated in order to achieve something close to herd immunity. "Once you're vaccinated... you're probably pretty safe. Now, if we're still walking around with lots of transmission going on, among people who didn't get vaccinated, you may want to wear a mask as well."

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