Many companies and laboratories have developed testing to diagnose the novel coronavirus (COVID-19). Currently, there are three types of diagnostic tests available, including molecular tests, antigen tests, and antibody tests. Test results can be diagnosed in commercial, private and academic labs and are often ready within the same day. If you are feeling sick, it is recommended to contact your healthcare provider immediately and get tested, as advised.
COVID-19 Molecular Tests
Molecular tests, also known as diagnostic, viral, or RT-PCR tests, are currently the most common type of coronavirus testing.
US FDA summarizes the typical steps of molecular testing with the steps below:
- A doctor, pharmacist, or other health professional orders a COVID-19 test. All COVID-19 tests, including those used with a home collection kit, require a prescription or order from a health professional.
- You or a health care professional use a specialized swab to collect mucus from your nose or throat.
- You or a health care professional put the swab in a sterile container and seal it for transport to a lab.
- During the shipping process, most molecular test swabs must be kept within a certain temperature range so that the test will be accurate. The sample must arrive at the lab within 72 hours.
- A lab technician mixes chemicals with the swab to extract the genetic material of any virus that may be on the swab.
- The lab technician uses special chemicals, called primers and probes, and a high-tech machine to conduct several controlled heating and cooling cycles to convert the virus’s RNA into DNA, and then make millions of copies of the DNA. Some tests use only one warming cycle to make copies of the DNA.
- When DNA binds to specific probes, a special type of light is produced that can be seen by the machine and the test shows a “positive” result for infection with SARS-CoV-2, the virus that causes COVID-19.
Source: FDA, Coronavirus Testing Basics, https://www.fda.gov/consumers/consumer-updates/coronavirus-testing-basics
Mechanical Testing of the Nasopharyngeal Test Swab
For manufacturers to verify that nasopharyngeal (nasal for short) swabs utilized for COVID-19 testing are both safe and effective, they must be mechanically tested using a materials testing system. The primary concern when evaluating the efficacy and safety of nasal swabs is ensuring the swab will not break when subjected to mechanical forces associated with the swab encountering an obstruction within the nasopharyngeal space. As nasal swabs are subjected to both axial and rotational forces when removing and rotating the swab, tensile and torsion test methods can be implemented to determine the swabs strength characteristics. By performing the above mechanical tests on swabs, manufacturers can verify the swabs they develop will meet safety requirements.
Tensile testing is performed on nasopharyngeal swabs to simulate the tensile force that would be exerted on a swab if it was caught on an obstruction while being removed from the patient’s nose/throat. Manufacturers can evaluate the maximum tensile force of swabs to confirm they will not break if caught within the nasal passage.
The tensile test setup for nasopharyngeal swabs includes a universal testing machine with tensile grips such as manual vise or pneumatic vise grips. During the test, the two ends of the swab, clamped between the tensile grips, are pulled to determine properties such as the breaking strength and the elongation at break.