Here are the cases where the result of the corona test is false negative

Dubai, United Arab Emirates (CNN) – If you think a negative test result means you do not have the coronavirus, you could be wrong.

It may take days for the infection to appear in the “Covid-19” test.

“We know that the incubation period for COVID-19 is up to 14 days,” said the emergency physician dr. Lena Wayne told CNN. Before that, your test results may be negative, and you have no symptoms. But you can actually be infected with the virus and have the ability to transmit it to others.

So, if you want to take the test as a precaution before meeting friends or family, here is what you need to know:

If you were injured yesterday, will today’s test reveal it?

Often the answer is no. A study in the Annals of Internal Medicine examined false-negative test results for people who had already contracted COVID-19.

The study estimated that within 4 days of infection before symptoms usually started, the probability of getting a wrong / negative test result on the first day was 100%.

According to the study, the average false negative rate dropped on the day people started showing symptoms to 38%. Three days after symptoms began, the false negative rate was reduced to 20%.

“The virus takes time to replicate in the body to detectable levels,” said Justin Lessler, senior author of the study and assistant professor of epidemiology at Johns Hopkins Bloomberg School of Public Health.

“You can get infected with just a few viral particles, but it will not be detected until they have had time to multiply to levels suitable for detection,” he told CNN in an email.

So, how many days does a person have to wait for a potential exposure to get the test?

“There is no hard and fast rule, but the evidence suggests that testing before the third day after exposure is of little benefit,” Lessler added.

Can I be contagious during a negative test?

definitely. “People feel as if you have a[negatiewe]get test, you do not run a risk. But that’s not true, “said Dr. Rochelle Wallinsky, chief of Infectious Diseases at Massachusetts General Hospital.

Wallensky added that for people who contract the coronavirus, symptoms can take up to two weeks to appear, but the average time is about 5 days.

One of the reasons why this virus spreads easily is that people can spread the infection without any symptoms. The U.S. Centers for Disease Control and Prevention estimates that 40% of infections are asymptomatic, and that 50% of transmission occurs before symptoms begin.

Are the different types of Covid-19 tests important?

And when it comes to diagnostic tests – those that determine if you have an active coronavirus infection, there are two main types:

Molecular tests, such as polymerase chain reaction (PCR) tests, that look for the genetic material of the virus. Most of these tests are done using nasal swabs or throat swabs, although some may use saliva, the FDA says.

“This test is usually very accurate and usually does not need to be repeated,” says the Food and Drug Administration.

But the downside of the molecular test is that the results can take some time.

Antigen tests are often known as fast tests (although some molecular tests are also fast). Antigen tests are not antibody tests, which tell you if you have been infected with the virus before and have already developed antibodies against the infection. Antigen tests do not look for the genetic material of a virus, as molecular tests do. Instead, it searches for specific proteins on the surface of the virus.

The good news is that you can get antigen test results in less than an hour. The bad news is that you are more likely to get a false negative result with a quick antigen test.

“Positive results are usually highly accurate, but negative results may need to be confirmed with a molecular test,” the FDA says.

Antigen tests are more likely to miss active MERS infection than molecular tests.

Can I test myself at home?

Yes. There are a few test kits available at home, such as the “Everlywell Covid-19” molecular test. Users take their nasal swab samples and mail them to a laboratory, which will digitally send the results within 24 to 48 hours of receiving the samples.

Dr. Frank Ong, chief medical officer and scientist at Everlywell, said it could be wrong to do any kind of COVID-19 test too soon.

He added: “The best advice I can give is to treat yourself as if you were probably infected after a suspected exposure. Quarantine, wear a mask to cover your nose and mouth, and practice good hygiene. If you want to take extra precautions or think you are infected, do Do the test with an FDA-approved test.

What should I do if I want to see friends or family?

And if you insist on seeing your loved ones on Thanksgiving, Walinsky said, a 14-day quarantine advance is probably the safest bet.

Lesser agrees that quarantine is best, saying, “If you are visiting an elderly family member and have a reasonable risk of being exposed to the virus, there is no alternative to spending 14 days of quarantine.”

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