By NASEEM S. MILLER
ORLANDO SENTINEL
SEP 12, 2020 AT 5:30 AM
Antigen tests offer similar info to molecular tests, and within as little as 15 minutes following a nasal or throat swab. Antigen tests, which detect small pieces of the novel coronavirus that trigger immune system response, are less sensitive than PCR tests: If a patient has COVID-19 symptoms but a negative antigen test result, it is recommended they get a PCR test to be certain they don’t have the virus. However, when it comes to a positive test result, antigen tests are highly accurate. This test is less expensive and complex, and faster than the other two types of approved diagnostic tests (molecular and PCR), so it can be useful in testing the masses; some experts predict that these tests may be widely availableby this winter.(Canva)
Antigen testing can be a useful tool in identifying asymptomatic health-care workers who have been exposed to COVID-19, according to a recent study by AdventHealth researchers.
The pre-publication study of about 500 AdventHealth health-care workers showed that about 2% of workers who had no symptoms tested positive for COVID-19 after an antigen test, which produced results in 15 minutes.
Researchers said their findings show that antigen tests, even though less accurate than the gold-standard PCR test, is a cost-effective way to help relieve anxiety and reduce the number of lost workdays, especially when there’s a COVID-19 surge and limited PCR testing availability.
“After we completed the pilot and saw that it worked, this is now our standard [for employee testing],” said Dr. Victor Herrera, associate chief medical officer of AdventHealth Orlando and an infectious disease doctor.
Antigen tests for COVID-19 first received emergency use authorization from the FDA in May, and AdventHealth was one of the first adopters of the rapid test in Central Florida.
The test looks for certain proteins of the novel coronavirus, instead of its genetic material, which is identified by the highly accurate PCR tests. But it’s less accurate than the PCR test.
"A good general principle to remember is that [the antigen test] has a very high specificity. And what that means is if the test says you have this, there is a really good chance you have it,” said Dr. Patrick Godbey, president of the College of American Pathologist. “The problem with many antigen tests is sensitivity. In other words, if I have COVID-19, how likely is it that this test is going to say I have COVID-19 and that varies tremendously.”
For instance, in the AdventHealth study, of the 139 health-care workers who had symptoms of COVID-19, 124 tested negative with the antigen test. The health system then performed a PCR test on those individual and identified five who were positive.
Still, experts argue that during the pandemic, when resources are limited and time is of essence, having a test that’s rapid, cheaper and requires less complex equipment is better than having access to no tests.
As many as 40% of adults who have the virus show no symptoms, a characteristic unique to the novel coronavirus, and can transmit the disease.
Late last month, the Centers for Disease Control and Prevention changed its recommendation to say that people who have no symptoms but have been exposed to someone with COVID-19 don’t need to get tested. The guidance was swiftly met with backlash from public health experts. The agency now says that if you have no symptoms but have been exposed to someone with COVID-19, “You do not necessarily need a test unless you are a vulnerable individual or your health care provider or state or local public health officials recommend you take one.”
Outside of this study, AdventHealth has performed more than 100,000 antigen tests so far at its Centra Care urgent care centers on people who have had COVID-19 symptoms or were exposed to someone with a known infection, said Herrera.
"When I think back of those 100,000 tests, I think it’s a huge contribution because that resulted in positive results in people who then changed their behavior because of that and probably stopped a lot of transmissions,” he said.
The AdventHealth study on health-care workers, which was performed between June 18 to July 21 on those who were exposed to confirmed COVID-19 cases at work or in the community, also showed that 11% of those who had symptoms tested positive for the virus with the antigen tests.
Health-care workers who tested positive for the virus or tested negative but had a high-risk exposure to COVID-19 were asked to self-isolate. Those who had low-risk exposure, had no symptoms and had a negative antigen test could return to work.
Overall, 5% -- or 27 out of 497 health-care workers -- tested positive in the pilot study.
“The biggest surprise from the study was that the number of health-care workers who were positive was relatively low and that validated our strategies to keep our team safe in terms of [personal protective equipment] and all the things we do,” said Herrera.
ORLANDO SENTINEL
SEP 12, 2020 AT 5:30 AM
Antigen tests offer similar info to molecular tests, and within as little as 15 minutes following a nasal or throat swab. Antigen tests, which detect small pieces of the novel coronavirus that trigger immune system response, are less sensitive than PCR tests: If a patient has COVID-19 symptoms but a negative antigen test result, it is recommended they get a PCR test to be certain they don’t have the virus. However, when it comes to a positive test result, antigen tests are highly accurate. This test is less expensive and complex, and faster than the other two types of approved diagnostic tests (molecular and PCR), so it can be useful in testing the masses; some experts predict that these tests may be widely availableby this winter.(Canva)
Antigen testing can be a useful tool in identifying asymptomatic health-care workers who have been exposed to COVID-19, according to a recent study by AdventHealth researchers.
The pre-publication study of about 500 AdventHealth health-care workers showed that about 2% of workers who had no symptoms tested positive for COVID-19 after an antigen test, which produced results in 15 minutes.
Researchers said their findings show that antigen tests, even though less accurate than the gold-standard PCR test, is a cost-effective way to help relieve anxiety and reduce the number of lost workdays, especially when there’s a COVID-19 surge and limited PCR testing availability.
“After we completed the pilot and saw that it worked, this is now our standard [for employee testing],” said Dr. Victor Herrera, associate chief medical officer of AdventHealth Orlando and an infectious disease doctor.
Antigen tests for COVID-19 first received emergency use authorization from the FDA in May, and AdventHealth was one of the first adopters of the rapid test in Central Florida.
The test looks for certain proteins of the novel coronavirus, instead of its genetic material, which is identified by the highly accurate PCR tests. But it’s less accurate than the PCR test.
"A good general principle to remember is that [the antigen test] has a very high specificity. And what that means is if the test says you have this, there is a really good chance you have it,” said Dr. Patrick Godbey, president of the College of American Pathologist. “The problem with many antigen tests is sensitivity. In other words, if I have COVID-19, how likely is it that this test is going to say I have COVID-19 and that varies tremendously.”
For instance, in the AdventHealth study, of the 139 health-care workers who had symptoms of COVID-19, 124 tested negative with the antigen test. The health system then performed a PCR test on those individual and identified five who were positive.
Still, experts argue that during the pandemic, when resources are limited and time is of essence, having a test that’s rapid, cheaper and requires less complex equipment is better than having access to no tests.
As many as 40% of adults who have the virus show no symptoms, a characteristic unique to the novel coronavirus, and can transmit the disease.
Late last month, the Centers for Disease Control and Prevention changed its recommendation to say that people who have no symptoms but have been exposed to someone with COVID-19 don’t need to get tested. The guidance was swiftly met with backlash from public health experts. The agency now says that if you have no symptoms but have been exposed to someone with COVID-19, “You do not necessarily need a test unless you are a vulnerable individual or your health care provider or state or local public health officials recommend you take one.”
Outside of this study, AdventHealth has performed more than 100,000 antigen tests so far at its Centra Care urgent care centers on people who have had COVID-19 symptoms or were exposed to someone with a known infection, said Herrera.
"When I think back of those 100,000 tests, I think it’s a huge contribution because that resulted in positive results in people who then changed their behavior because of that and probably stopped a lot of transmissions,” he said.
The AdventHealth study on health-care workers, which was performed between June 18 to July 21 on those who were exposed to confirmed COVID-19 cases at work or in the community, also showed that 11% of those who had symptoms tested positive for the virus with the antigen tests.
Health-care workers who tested positive for the virus or tested negative but had a high-risk exposure to COVID-19 were asked to self-isolate. Those who had low-risk exposure, had no symptoms and had a negative antigen test could return to work.
Overall, 5% -- or 27 out of 497 health-care workers -- tested positive in the pilot study.
“The biggest surprise from the study was that the number of health-care workers who were positive was relatively low and that validated our strategies to keep our team safe in terms of [personal protective equipment] and all the things we do,” said Herrera.
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