BY DR. ANDREW WILLIAMS

President, St. Lawrence County Board of Health

There are three main types of testing for COVID 19 in St. Lawrence County at this time. Although your medical provider, occupational health or public health expert may be involved in determining which test is right for you, the following information is designed to help you understand the basics of each test and how they are most effectively used.

As members of our community, you should understand what it means, or does not mean when you are told that employees, travelers, students or others are tested for this virus.

First, RT-PCR or “molecular” tests detect the presence of viral RNA in a sample and can be collected in a medical office, pharmacy, hospital setting or testing center. RT-PCR/molecular tests are considered the “gold standard” for detecting active infection.

St. Lawrence Health System and Claxton Hepburn Medical Center only use RT-PCR for testing, as will the four area universities. A nasal, nasopharyngeal or salivary sample is obtained and RT-PCR/molecular tests and can be run on-site (eg., Abbot ID-now, Cepheid, Biofire) or sent to a reference lab (eg., Mayo, Broad Street, Labcorps). Turn-around time for results can be as little as one hour for on-site testing or as long as one week for reference labs.

Unfortunately, there is a shortage of the rapid on-site version of these tests, so they are conserved for testing in situations where results are needed urgently. These tests are the most accurate tests and a negative result does not need to be confirmed by a repeat test.

Because of the greater accuracy of RT-PCR tests, they can be used to rule out infection and may be used to test travelers, students, healthcare workers, and other essential employees. This test can be used with individuals who have symptoms and those who do not. Individuals who have symptoms and those who do not (asymptomatic) are contagious and can spread the virus.

Second, Rapid Antigen based tests (eg., Quidel/Sofia) are rapid tests that detect viral proteins. These tests are performed for symptomatic individuals in some medical offices and urgent care centers. Positive results are usually accurate, but negative results are not reliable and need to be confirmed with a more accurate test. Used in the proper context, these tests can be helpful. Because of the high false negative rate, antigen tests should not be used to test individuals with no symptoms. That includes travelers from high-transmission regions, students, healthcare workers, or other essential employees. St. Lawrence Health System and Claxton-Hepburn Medical Center do not currently offer this test. A recent guidance from the Association of Public Health Labs strongly discouraged the use of this test for people without symptoms. Using this test with these groups provides “false reassurance.”

Lastly, serological (antibody) tests require a blood sample to look for antibodies to the coronavirus, which causes the COVID-19 illness. Serology tests cannot tell you if you currently have an infection and should not be used for screening of high risk travelers, healthcare workers or other essential employees. These COVID-19 antibodies typically develop after an individual has been infected with the virus for at least seven days. Antibodies may be present for weeks or months after the infection has resolved. Serological testing is most useful for research purposes to help public health officials determine how many people in a region have already been exposed to the virus.

Unfortunately, the presence of antibodies does not appear to guarantee immunity against future infection. Results for serology testing can be available within hours or up to three days.

Although there is a list of priority groups for testing, on July 2, New York State indicated that any individual is eligible for testing. Anyone with significant symptoms -- shortness of breath, persistent cough, high fever -- should contact their medical provider or seek emergency care. Patients with acute illness will usually be tested with a rapid RT-PCR/Molecular test. Preoperative or pre-procedure testing is arranged by the patient’s surgical team.

Other individuals who require testing should contact one of the testing centers in St. Lawrence County. There are four sites run by St. Lawrence Health System (315-261-6240) and a respiratory clinic run by Claxton Hepburn Medical Center (315-713-6655). Clifton-Fine Hospital's COVID-19 testing hotline number is 315-848-8049.

Both SLHS and CHMC hospitals have the ability to perform RT-PCR/molecular tests when indicated. Most tests done for screening purposes are sent to reference labs (large university or commercial labs that test the locally collected specimen). Wait times for results from tests that are sent to reference labs have increased nationally. However, both hospital systems in SLC are working to make sure the results return as soon as possible.

Depending on the indication for testing, a patient’s health insurance, employer or New York State may cover the cost of testing. Even with the “gold standard” RT-PCR test, there is a small possibility of having a “false negative” test, where you have the infection, but the test result is negative, but this is very uncommon. Even more rare is a “false positive” test where you do not have the infection, but the test is reported as positive. Test results must be interpreted by a medical provider or public health expert in the context specific to the individual.

Innovative testing strategies including the use of batched or pooled samples, which means running samples from multiple individuals in one test, will be available in St. Lawrence County at some point in the future. This approach will allow a more efficient and economical approach to testing large groups of individuals for COVID-19.

Additionally, less intrusive collection options, like taking saliva from the mouth, are being developed and validated. All of these efforts are an essential component of the health care community and the public health department’s efforts to keep the North Country Region open. Regardless of advances in testing, nothing replaces the “five pillars” of our community response to the pandemic -- wear a mask, social distance, wash your hands, stay home when ill and avoid unnecessary travel.

References: https://www.aphl.org/programs/preparedness/Crisis-Management/Documents/APHL-SARSCov2-Antigen-Testing-Considerations.pdf

Dr. Williams is also chief medical officer of the Community Health Center of the North Country, associate chief medical officer of St. Lawrence Health System and an assistant clinical professor at University of Rochester School of Medicine.

Don’t Miss a Story!

Keep up with local government & schools, police & fire news, help wanted ads, upcoming events, obituaries, letters from viewers, news of your friends & neighbors, & much more!
Subscribe today for just $1.44 per week
 Thank you.