The discussion related to coronavirus has for long been focused on the number of Covid-19 cases and the capacity of testing in hospitals and laboratories. Over the past few weeks however, the focus has moved to the possibilities of antibody tests, and weather they could provide a way to reopen countries, while keeping the public safe. The key for this to happen would be mass testing, and finding those who have already faced the disease, possibly without any symptoms, and now have antibodies in their blood. These employees could safely return to their workplaces, where as those who have not developed immunity to Covid-19, should still stay home and avoid social interaction with other people.
In some countries there is already discussions about official certificates of immunity, kind of immunity passports. Such document would be given to people who have tested positive for Covid-19 antibodies, and they would be free to get back to normal life. In fact in Chile a version of such document has already been taken in use. New York state recently completed antibody tests determining that approximately 14% of people in New York state and 20% of people in NYC tested positive for antibodies, so this really could be a huge step for world to start opening up again.
Antibody testing shows promising signs, but there are still a lot of open questions regarding testing and immunity. Concerns have been raced related to the accuracy of many antibody tests, and the capacity of test manufacturers – the volume needed for mass screening is huge. Furthermore, even once there will be a sufficient number of reliable tests available, it’s still unsure how effective the immunity to Covid-19 actually is and how long it will last.
How antibody testing actually works?
Antibody tests can determine who has ever been infected, and who may be immune to re-infection. This can be very helpful for guiding strategies for non-pharmaceutical interventions such as social distancing measures. When someone gets infected with a virus, their immune system must work out how to fight it off and produce substances called antibodies. These are extremely specific and are usually only able to tackle one strain of one virus. For example, if someone has a Covid-19 infection, they will develop anti-Covid-19 antibodies. The body then stores versions of these antibodies in the immune system, so that if it comes into contact with that same virus again, it should be able to fight it off.
An antibody test looks for evidence of the body’s immune response to a virus, and thus points out persons that have had the disease. These tests are usually done from a small drop of blood. Depending on the timing and accuracy of the test, they can potentially also identify who is currently infected. Mass screening with antibody tests and data analysis can also help to build a more complete picture of epidemic course, attack rate, and fatality ratio. Furthermore, it is a tool for determining the full spectrum of the disease severity and the extent and permanency of immunity.
There are five kinds of antibodies, but two principal ones linked to immune response are of particular interest: Immunoglobulin M (IgM), which is the first antibody to appear and represents signs of recent infection, and Immunoglobulin G (IgG), which remains in the body after convalescence (recovery). The illustration below shows how this works – noting that the timings of antibody creation for Covid-19 are approximate and still subject to further research. In this discussion, it is important to note that a proportion of persons with Covid-19 infection clears the infection without showing any symptoms (asymptomatic) and some individuals take a few days before they show symptoms (pre-symptomatic).
To screen large populations for Covid-19 antibodies, cost-efficient rapid testing is the key. Results of these tests are available in minutes, where as laboratory results often require several days of waiting. An IgM-IgG Covid-19 test compared to other tests, is more convenient with low cost and can be performed in point of care, that could be in field, diagnostics kiosks, mobile diagnostics labs, bedside at hospitals or in clinics and laboratories. iSTOC Mobile Diagnostics Solutions improves the testing process and data collecting, and also ensures the quality of testing. It is a fully digitized and automated system that identifies the patient and the test environment, and all data points are digitally recorded. Delivery of the results is human-error free, the diagnosis is fast and accurate, and the result reports are available in real time.
Cover picture: by Gerd Altmann from Pixabay