Why are antibody tests important?
Not everyone who has been infected with coronavirus experiences symptoms and goes to the doctor’s. And not everyone has been tested. So, it is difficult for researchers to estimate how many people have actually been ill and how many have been infected. An antibody test allows for a rough estimate of unknown cases and thus a better monitoring of the spread of the virus. This is an important factor when it comes to deciding whether contact limitations and other measures can be relaxed.
How do antibody tests help? If you have been infected with coronavirus SARS-CoV-2, you probably carry the antibodies. These antibodies can be detected in your blood by laboratories. This will indicate if you have already been infected with Covid-19 and are therefore likely immune to further infection.
Who should take the test?
The antibody test is helpful for people who want to check if they have already been infected with Covid-19. In some cases, the novel coronavirus causes mild flu-like symptoms or even no symptoms whatsoever. This is why many people are unsure whether they may have already had the virus.
The antibodies can be detected one to two weeks after the beginning of infection. A good rule of thumb is that the test is useful starting at around 14 days after you experienced flu-like symptoms.
If you currently have symptoms of the flu or cold, then a test is probably not useful – antibodies cannot always be detected in the earlier stages. If you want to test for a current infection, you need a PCR test, like the cerascreen® Coronavirus Test to detect the presence of the genetic material of the virus (currently only available in Germany).
How does the test work?
The cerascreen® Antibody Test is a sample-taking and send-in kit for home use. It involves taking a small blood sample from a fingertip – you can take it where and when is convenient for you. After taking a blood sample, simply send the dried blood spot card to our diagnostic laboratory.
The laboratory uses the established ELISA analysis method to test your blood for IgG coronavirus antibodies. When the analysis is complete, you will receive a notification by email or the My cerascreen® app. You can then download your personal results report with your test result.
How conclusive is the test?
The cerascreen® Antibody Test uses scientifically established measurement techniques for detecting Covid-19 antibodies. It is a diagnostically conclusive method for determining if a coronavirus infection has occurred.
Just as with all medical tests, it is not 100% accurate. In rare cases, it can lead to a false positive (you tested positive, but have not yet had the virus) or a false negative (you tested negative, but have already had the virus).
The accuracy of laboratory tests like the cerascreen® Antibody Test is, however, considerably higher than quick tests that give a result without having been analysed in a lab.
What do the results tell me?
The results report will tell you if your result was positive or negative. Positive means that antibodies to SARS-CoV-2 were detected in your blood. ‘Negative’ means they were not detected.
A positive result can be an indication that you have already been infected with coronavirus.
How long does immunity last?
Studies from Canada and the United States, for example, have been able to detect neutralising antibodies for up to eight months after a Covid-19 infection. But it is not yet clear how long the antibodies usually remain in the body after vaccination or illness. Researchers are investigating this further – along with the question of how long people are immune to SARS-CoV-2 after vaccination or illness.
People in Ireland are now being asked to have their booster dose, which is normally with the Pfizer/BioNTech vaccine or Moderna vaccine. Research needs to be carried out regarding the effectiveness of a booster jab, as this is still considered a recent development.
Scientists also suspect that even after immunity has expired, there is still a certain degree of protection – what we call basic immunisation. In such instances, the coronavirus would presumably only trigger mild symptoms, such as a cough, cold and sore throat after a certain time.
Other studies from China and South Korea have suggested that people there have been infected with the virus multiple times or that the virus was reactivated. According to some virologists, this could be due to the measurement method, which can result at certain times in a negative result even though the virus is still present in the body.
Do I need to report my result?
No. In contrast with results from a PCR test, you are not required to report your antibody test results. Neither you nor the lab is required to report the result to the public health office.
There are still no special regulations currently for people with a positive antibody test result. Even if one is possibly immune, the contact restrictions still apply.
What does immunisation mean?
When pathogens like a virus enter the body, the immune system is on full alert to fight them. In this process, antibodies are created.
Antibodies are designed for certain pathogens. The specified antibodies recognise the virus or bacteria and bind to it, which allows the defence cells to attack it. If, together with other components of the immune system, they ensure that the pathogens cannot trigger the disease again, this is called immunity.
If your body has produced these antibodies at any time, they remain in the body. How long they remain there for depends on the class of antibody. IgG antibodies for instance can remain active to fight viruses for years in some cases.
Does a positive result mean I am immune?
It is currently not yet scientifically confirmed if one becomes immune after a coronavirus infection. However, researchers are optimistic after early studies with humans and monkeys have revealed that most people develop immunity after recovering from a Covid-19 infection.
Other studies from China and South Korea have suggested that people there have been infected with the virus multiple times. According to some virologists, this could be due to the method of testing, which can result at certain times in a negative result, even though the virus is still present in the body.
Is there a coronavirus hotline?
For urgent questions about coronavirus, phone your GP and they will assess you over the phone or contact HSELive on 1850 241 850
In case of an emergency, such as difficulty breathing, dial the emergency number 112 or 999.
What do SARS-CoV-2 and Covid-19 mean?
SARS-CoV-2 is the scientific denomination for the novel coronavirus. The abbreviation stands for Severe Acute Respiratory Syndrome Coronavirus 2.
Covid-19, on the other hand, stands for the illness that the virus causes. It is the shorthand designation for Coronavirus-Disease-2019. The year represents the first outbreak of the disease in China in December 2019.
People of all ages are susceptible to Covid-19. Children under 15 years of age are less often affected, but some infants have already been infected.
Difficult and potentially dangerous infections happen primarily among older people and people with pre-existing health conditions (for example, cancer, heart disease, diabetes, respiratory conditions, asthma), as well as smokers, in some cases.
What are the symptoms?
Data from China where the first virus outbreak was recorded show for around 80 per cent of cases, people experienced mild or moderate symptoms. For these cases, symptoms included a (typically dry) cough, fever and sometimes a head cold, or even mild pneumonia.
Some patients experience absolutely no symptoms, but are still contagious; they are so-called carriers.
In the meantime, studies suggest that the loss of smell and taste can be a symptom of the coronavirus.
Severe cases range from acute pneumonia with difficulties breathing and respiratory issues to life-threatening lung and organ failure.
According to the HSE, further symptoms that are less common but have been reported include: - Fever or chills
- Loss of appetite and weight loss
- Aches and pains
Who is the test not intended for?
The Coronavirus Antibody Test is not intended for the following groups of people:
- People with infectious diseases, like hepatitis and HIV, may not use the Coronavirus Antibody Test.
- People with haemophilia should not take the test.
- Pregnant and breastfeeding women should only take the Coronavirus Antibody Test under medical supervision. The given reference ranges and recommendations do not apply for people in this group; consult your medical professional for advice concerning your test results.
- The Coronavirus Antibody Test is not intended for children under 18 years of age.
- The test is not meant to diagnose an acute infection of the coronavirus. If you have flu symptoms, contact your doctor or the local health office. Current symptoms can be followed up with a PCR test, such as the cerascreen® Coronavirus Test (currently only available in Germany).