How can I understand whether I am COVID or FLU?
As the clinical signs and symptoms of respiratory viral infection with SARS-CoV-2 and influenza can be very similar, it is essential for healthcare professionals to quickly detect and differentiate between SARS-CoV-2 and different types of influenza. Especially during the flu season, quickly determining whether patients have an infection with SARS-CoV-2 or the flu and taking immediate action according to their diagnosis is critical for the treatment of patients and the reduction of viral transmission.
With the development of the COVID & FLU A/B Rapid Antigen Test, it is easier and quicker than ever for healthcare professionals to diagnose and differentiate infections with SARS-CoV-2, influenza A, and influenza B. This test is expected to aid in the long-term management of COVID-19 and seasonal flu and augment diagnostic capacity during peak periods. Here’s what to know about the test, its molecular mechanism, and procedure.
What are the symptoms of FLU and COVID-19?
Before starting to discuss about COVID & FLU A/B Combo Rapid test, we should go over their symptoms. Flu and COVID-19 have similar and common symptoms including fever, sore throat, runny nose, headache, cough and muscle or body aches. However, COVID-19 differentiates with symptoms such as loss of taste or smell, diarrhea, shortness of breath in some individuals. If you notice the symptoms mentioned above, it is best to get tested as soon as possible with a PCR or rapid antigen test (RAT) to reduce viral transmission and access to timely viral treatment if necessary. As rapid antigen tests (RATs) are very accurate for the detection of SARS-CoV-2 infections in symptomatic patients, you may also choose to take an over-the-counter rapid antigen self-test if PCR testing is not readily available to you. If you test negative on a rapid antigen self-test but your symptoms persist or worsen, you should either take a PCR test or perform serial rapid antigen testing to confirm your results.
What is COVID & FLU A/B Rapid Antigen Test?
The COVID & FLU A/B Rapid Antigen Test is a rapid chromatographic immunoassay for the simultaneous detection and differentiation of antigens specific to SARS-CoV-2, influenza virus A, and influenza virus B in human nasal or nasopharyngeal specimen. In a nutshell, it is an integrated combination test that allows rapid differential diagnosis for infections with any of these respiratory viruses using only a single patient sample. Designed for professional use in both laboratory and point-of-care settings, the COVID & FLU A/B Rapid Antigen Test enables healthcare professionals to quickly diagnose individuals with symptoms consistent with COVID-19 or influenza within the first five days since the onset of symptoms. By delivering three results from a single patient sample, this test increases the testing capacity, improves the management of patient treatment pathways, and enables immediate isolation for patients infected with SARS-CoV-2.
How Does It Work?
The COVID & FLU A/B Rapid Antigen Test is a lateral flow immunochromatographic diagnostic device detecting antigens specific to SARS-CoV-2, influenza A, and influenza B in anterior nasal or nasopharyngeal swab samples. Antigens are structural or functional components that are unique to a particular pathogen. If the targeted antigen is present in a patient sample in detectable concentrations, it will bind to assigned antibodies and form a visible signal on the assay. The COVID & FLU A/B Rapid Antigen Test checks for three different infections in a single sample and delivers three qualitative results in just 15 to 30 minutes.
How is the sample collected?
A) Collecting Nasopharyngeal Swab Samples
To collect nasopharyngeal swab specimen, first, patient’s head is tilted back 60-70 degrees to make the nasal passages more accessible. The sterile swab provided within the kit is gently inserted through the nostril of the patient parallel to the palate until resistance is felt, indicating a contact with the nasopharynx. In general, the swab should reach a depth equivalent to the distance from the nostrils to the outer opening of the ear. At that point, the swab is gently rubbed, rotated, and left in place for a few seconds. Then, the swab is gently removed wile rotating it. Although the same procedure can be repeated from the other nostril, it is not necessary if the fluid collected from the initial collection has already saturated the tip of the swab.
B) Collecting Anterior Nasal Swab Samples
To collect nasal specimen, the soft tip of the sterile swab is inserted into the nostril of the patient for 2 centimeters. Next, the swab is gently rotated and pressed against the inner wall of the patient’s nostril a few times for about 15 to 20 seconds before it is removed. The same procedure is repeated for the other nostril using the same swab.
What is the test procedure like?
After the sample is collected, the extraction tube should be opened, and the swab should be inserted into the tube. The swab is rotated 10 times within the extraction buffer solution along the inner wall of the tube. Next, the tip of the swab is squeezed along the inner wall of the tube to ensure that the specimen on the swab is completely transferred into the buffer. Then, the swab is broken at the assigned point and the extraction tube is closed again with the dropper head. The test cassette is removed from its aluminum packaging and laid out horizontally on a flat surface. Finally, three drops of the solution of the processed sample within the extraction tube is added to the sample wells for COVID-19 and Flu A/B. The results are ready to be read after 15 minutes. The results are considered invalid if read outside of the time specified within the instructions. All samples and materials should be disposed as bio-hazardous waste immediately after finishing the test.
How To Interpret the Results?
The COVID & FLU A/B Rapid Antigen Test delivers three separate results indicating the presence or absence of an infection with SARS-CoV-2, influenza A, and influenza B.
For SARS-CoV-2
- If only the C line appears, it means your result is negative for SARS-CoV-2.
- If the C and the T lines appear, it means your result is positive for SARS-CoV-2.
- In any scenario that the C line does not appear, your result is invalid and please re-operate the procedure.
For FLUA/B
- If only the C line appears, it indicates your result is negative.
- If the C and the A lines appear, it means your result is positive for FLU A.
- If the C and the B lines appear, it means your result is positive for FLU B.
- If the C, the A, and the B lines appear, it means your result is positive for FLU A and B.
- In any scenario that the C line does not appear, your result is invalid and please re-operate the procedure.
Negative results should be treated as presumptive and evaluated within the context of an individual’s medical history, exposures, symptoms, and vaccination status. Thus, especially for COVID-19, confirmatory testing with additional antigen or molecular tests may be requested by your healthcare providers.
References
- Piroth, L., Cottenet, J., Mariet, A. S., Bonniaud, P., Blot, M., Tubert-Bitter, P., & Quantin, C. (2020). Comparison of the characteristics, morbidity, and mortality of COVID-19 and seasonal influenza: A nationwide, population-based retrospective cohort study. The Lancet Respiratory Medicine, 9(3), 251–259. https://doi.org/10.1016/s2213-2600(20)30527-0