What are IgG and IgM?
Immunoglobulins are antibodies themselves and are part of our immune system. When we get an infection, such as COVID-19, immunoglobulins are produced, which attach to the virus and activate the rest of the immune system to attack and clear the virus. IgM is the first immunoglobulin to be produced and is a general antibody that can bind to many different types of pathogen. The presence of IgM is an indicator of early infection. IgG is a more specialized antibody that specifically binds to the SARS-CoV-2 virus. The presence of IgG is an indicator of later stage infection (usually 7 days or longer after infection).
Is the test specific for COVID-19?
The IgG that the test detects is specific to COVID-19, so a positive result would indicate COVID-19 infection. Although the IgM is a more generalized antibody, its presence, combined with IgG and/or the common symptoms of COVID-19, would also indicate infection with the novel SARS-CoV-2 virus. The test can be used for primary and secondary diagnosis of COVID-19.
What samples can I use?
The test cassette will work with whole blood, plasma or serum. Capillary blood is the easiest to obtain via a finger pinprick, however, venous blood obtained via venipuncture is also suitable. The type of sample will not affect the sensitivity or accuracy of the test.
What is the buffer solution for, and can I use any buffer with the test?
The buffer solution has two functions. It acts as the carrier for the sample, allowing it to laterally flow along the test strip, and it maintains a constant sample pH as it flows, preventing degradation of the biomarkers and the antibodies. We recommend that you only use the buffer solution provided with the test kits, as other ones may affect the accuracy of the test.
What do the results mean?
The test strip has three different lines; one for IgG, one for IgM and one control line. There are four different valid results:
IgM + Control – The sample is positive for IgM. This means the patient is in the early stages of an infection and combined with the common symptoms, is positive for COVID-19
IgG + IgM + Control – The sample is positive for both IgG and IgM and therefore positive for COVID-19
Control only – The sample is negative
If the control line does not appear, the test is void and should be repeated, irrespective of how many test lines are visible.
I didn’t read the results after 10 minutes. What should I do?
For the result, the window of accuracy is 10-15 minutes after you add the sample and buffer solution. If you forget to read the results after this time, the test may not be accurate, and you should repeat it.
How should I store the tests?
The recommended storage temperature is 2 – 30°C, however, we do not recommend you store them in the fridge, unless there is a risk of them overheating. Do not freeze the test cassettes or buffer solution. Tests should be performed at room temperature (15 – 30°C), so if you have stored tests in the fridge, you should allow them to reach room temperature before performing a test.
How accurate is the test?
A clinical study was conducted in Wuhan, China, where the lab compared the test cassette to conventional laboratory tests for COVID-19 diagnosis, which also detected the presence of IgG/IgM in 902 blood samples. They obtained the following results:
Sensitivity > 91%
Specificity > 99%
Accuracy > 97%
This clinical study is evidence of the usability and effectiveness of the test.
Can babies and young children be tested?
Yes, there are no issues with testing babies and young children.
Is there anyone that shouldn’t be tested?
No, the more people that are tested, the better it will be to understand the spread of the virus, which will result in better measures being taken to prevent its spread
However, as the test requires a blood sample, anyone with a blood-related health condition (such as hemophilia) should discuss this with a healthcare professional before performing a test.
Is the product already on the market, e.g. in United States?
This is a relatively new test but is now being used successfully in many countries around the world.
What should I do if I test positive?
If you test positive, you should follow the FDA’s advice on COVID-19 infection. This usually means self-isolation for 7 days, avoiding contact with others and remaining hydrated. Most cases of COVID-19 are mild, and recovery only takes a few days, so there’s no need to panic. Speak to your healthcare practitioner for further advice.
What if I test negative?
A negative result means the biomarkers are not present in your blood, but you should still exercise caution, as you may still be in the early stages of infection (before IgM levels rise to a detectable level). If symptoms develop, follow the protocols as above and retest as necessary. If symptoms do not develop, it is unlikely you have COVID-19 but should still follow strict hygiene procedures. Ensure you wash your hands regularly, avoid social gatherings and work from home if possible. There’s no need to retest unless you suspect you have contracted the infection and are displaying symptoms.
What if I test positive but don’t display any symptoms?
In this case, there are two options. Either you are infected and may begin to display symptoms in the next few days, or you are infected but are asymptomatic (you won’t display symptoms). In both cases, you should treat it as though you are positive for the virus and should follow the appropriate healthcare guidelines. Speak to your healthcare practitioner for further advice.
So can the test detect asymptomatic patients?
Yes, the test will be able to detect IgM/IgG in asymptomatic people, as they will have an immune response even though they don’t display symptoms. The timeline of infection will be the same as someone displaying symptoms.
What if I test negative but display symptoms?>
If you have the common symptoms of COVID-19 (fever and cough), you likely have contracted the infection and should self-isolate. It is likely your IgG/IgM levels haven’t risen to a detectable level yet. You can be tested again 24 hours later for confirmation id required. Speak to your healthcare practitioner for further advice.
What is the shelf-life of the test cassette?
The shelf-life is 18 months from the date of manufacture. The product expiry is printed onto the packaging for reference. Do not use after the expiry date.
Do any medications, drugs or other proteins in the blood affect the test result?
To date we have tested numerous common pharmaceuticals, none of which have interfered with the test. Also, Rheumatoid Factor does not interfere with the test, hence we currently see no cross-reactivity issues. We are looking at more drugs and will update customers accordingly.
Will IgG and IgM remain in the blood after I’ve recovered from COVID-19?
There is some evidence that IgG/IgM remains in the blood after recovery to prevent reinfection. We have tested some patients and noticed that they still test positive for at least 33 days after first displaying symptoms. You won’t be infectious after you recover, even if you test positive, but you should still be cautious as long-term immunity has not yet been confirmed and reinfection may still occur.
Can pregnant or breast feeding women be tested?
Yes, there is no harm to the mother or baby when performing a test.
Is this test FDA approved?
Authorized to market and distribute SARS-CoV-2 IgM / IgG Rapid Test kits to any licensed healthcare practitioner in the United States for diagnostic use while it awaits a final decision on its FDA EUA application. While the policy does not apply to at-home testing, the policy does allow testing in laboratories or by healthcare workers at the point-of-care.