White House press secretary Kayleigh McEnany said she had tested negative for COVID-19 “every day from Thursday,” until she tested positive on Monday.
McEnany’s disclosure shows the limitations of daily testing to prevent the spread of coVID-19 guilty coronavirus. A user would possibly have lines so small of the virus after exposure that a case is not known until a few days later, even with the utmost precision. and delicate evidence.
This is “what we call a window era: it’s the era after you get inflamed and before you have a positive test,” said Dr. Richard Scanlan, president of the Accreditation Council of the College of American Pathologists.
The growing epidemic of others connected to President Donald Trump brings new scrutiny to the White House strategy, which is based on controlling everyone in close contact with the president. But experts say a coronavirus control is just a snapshot at any given time.
Some public fitness experts criticize the White House for giving so much importance to common tests. Test specificity levels in all spaces; some want small amounts of viral waste to produce a positive result, while others require tens of thousands of waste.
The most sensitive type of verification is the polymer chain reaction, or PCR, which amplifies a small amount of DNA pattern from a nasal swab. PCR checks are performed in laboratories and can take days to process, although some portable machines can produce effects in less than an hour.
PCR tests can detect a virus 4 days after a person’s infection, Scanlan said.
Antigen testing, which runs into coronavirus proteins, is less expensive and produces effects faster than maximum types of PCR testing.
The U. S. Department of Health and Human ServicesHe bought thousands of antigen machines and sent them to nursing homes. HHS also purchased 150 million fast antigenic strip tests called BinaxNOWArray manufactured through Abbott Laboratories.
But antigenic tests are less sensitive than PCR tests and do not detect an infection until about seven days after a person is infected, Scanlan said.
A user who becomes ill develops symptoms 4 or five days after exposure, but symptoms can vary from two to 14 days after infection and many others never get sick.
“Therefore, the PCR test begins to detect the virus about a day before symptoms expand, while antigen verification may take place a few days after symptoms appear,” Scanlan said.
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The White House has conducted immediate coronavirus checks since March, but faster controls have emerged since spring and other technologies have provided the White House medical team with a menu of functions for quick control. It is not known what control was used for McEnany.
A user in the early stages of the disease may also not have enough viral load to show a positive result, but it can still be infectious.
Dr. Lewis Nelson, professor and president of emergency medicine at Rutgers New Jersey School of Medicine, said tests can definitively tell a user that they were negative at the time the test was conducted. the user may have been exposed.
“It’s a general time part that at that time is negative,” he said. “By the time your check turns negative, it won’t be negative anymore. “
The U. S. Centers for Disease Control and Prevention has been in the process ofBut it’s not the first time They recommend 14 days of quarantine after close contact with a user who has suspected or shown COVID-19, regardless of positive or negative result.
President Trump has refused to wear a mask and even rebuked former Vice President Joe Biden for dressing up in one forever.
Ken Alltucker is on Twitter @kalltucker or can be emailed to alltuck@usatoday. com