The coronavirus cases and death toll in Austria have stabilized even during the first steps of reopening the country. However, it’s not over yet. Without a cure, vaccine, or widespread SARS-CoV-2 immunity, we haven’t reached the end of the pandemic. There is still a threat of new outbreaks.
Now, the key is testing for COVID-19 – to end the crisis, and allow the economy to recover fully. We know this works: The success with the coronavirus pandemic in countries like Iceland and South Korea is evidence that mass testing is essential. Testing will help us determine whether we are vulnerable to a new outbreak.
The benefits of widespread testing
The rational is simple: Comprehensive testing for COVID-19 allows us to understand and follow the progression of the pandemic. It is especially important for identifying people who have active infection and who have recovered from it. Only then is it possible to stop the virus from spreading and to determine who is immune and protected from reinfection.
Testing helps especially by identifying people who are asymptomatic, but still contagious. COVID-19 spreads easily between people in close contact, so anyone who is infected even without symptoms could reduce spread by self-isolation and social distancing. Early testing can control viral spread and prevent outbreaks that overload hospitals with high numbers of severely ill people.
Testing is also key to figuring out who has had a COVID-19 infection, because developing immunity most probably protects them from reinfection and would allow them to resume their social and professional lives. Protection against SARS-CoV-2 would especially be necessary for healthcare workers to be able work without fear of becoming infected or of infecting their patients, friends, and families.
Most of all, testing will give us a new measure of control: Once we isolate infected people, we can trace and quarantine their contacts, to further understand how COVID-19 spreads, and guide treatment. The testing data will also help us allocate medical resources and evaluate whether the measures like social distancing and lockdown are useful and necessary.
Who should get tested
Testing matters most, of course, for acute infection. People who are asymptomatic or have a mild case – which is most of those infected – have so far been advised to recover at home and as far as possible, stay away from others. On this reasoning, testing priority has been given to people in contact with confirmed COVID-19 patients or to those in a high-risk area or job. Additional priority groups have been the elderly in long-term care facilities, the immunosuppressed, those hospitalized with severe illness and people with underlying medical conditions who are at high risk of becoming severely ill.
However some experts argue that far-broader, random testing across the population is needed to help determine the overall infection rate, and allow us to gauge our response to new infections and the potential for a massive second wave. Granted, this would be expensive. But it could make possible a far faster return to normal economic and social life.
What the tests tell us
COVID-19 Testing can reveal both the active presence of the virus or a person’s response to the virus – in other words, if someone is actively infected and contagious, or previously infected and probably not able to spread the virus anymore.
Testing negative is also informative, but not conclusive as the result could be a false negative, i.e. a failure to detect someone in fact has the disease. A false negative is dangerous as it leads to a false sense of security and the unwitting spread of the virus to others.
What kinds of tests are available?
Most available tests measure one of two things: either the virus’ specific genes or its proteins. The most common is the reverse transcription polymerase chain reaction (RT-PCR or PCR) test, which detects the coronavirus genetic sequences. An alternative method is to identify viral proteins rather than genetic material from the SARS-CoV-2 virus. However, it may not be as sensitive as the PCR method.
The PCR test analyzes cells collected from the nose or back of the throat, and if the sequences are present, the sample contains the virus. This is the most reliable for confirming infection. The standard PCR test takes several hours and requires laboratory equipment and skilled technicians. However, there are new fast PCR tests using handheld devices capable of isothermal nucleic acid amplification, which takes minutes instead of hours. These units are portable for quick testing in the workplace, schools, airports, and even at home. An advantage is that using this technology makes it easy to test the same person repeatedly.
Although PCR is the most sensitive test for COVID-19 infection, there can be problems if the sample isn’t good enough, in other words, if it wasn’t taken, transported, or stored correctly, or was collected too soon after infection. If you were given the fast genetic test, you might be one of the 15% of people with a false negative. In such cases, it is often necessary to repeat the test.
It is also possible to measure immune response with an antibody test. The SARS-CoV-2 infection induces
antibodies whether or not a person had any symptoms or even knew that they were infected. Currently, there are antibody tests available, but as this virus is new, scientists are continually improving and optimizing them.
The current test measures coronavirus antibodies in a blood sample and is positive only after being infected with the SARS-CoV-2 virus. When a person has an COVID-19 antibody response, it usually means – as with viral infection or vaccination for measles or influenza – that a person cannot become infected a second time.
The antibody response against SARS-CoV-2 takes up to 3 weeks to develop and does not tell us whether the person was acutely infected. However, antibody tests detect two types of antibodies, IgM and IgG, the first of which rises during an active infection and the second when the person is recovering or recovered.
So testing for antibodies is useful for identifying who has been infected and allows us to trace the spread of the virus. Unfortunately, we still do not know for sure whether the COVID-19 antibodies are protective and how long the protection lasts. Long-lasting protective antibodies would ensure that previously infected people can’t spread the virus, and could guide vaccine development.
Also, if these antibodies were found in a high enough percentage of the population, they could protect ‘never infected’ people through herd immunity. When we confirm that the COVID-19 antibodies are protective, we could consider passive immunization, which means that immune people could donate their blood, which contains the antibodies, to help treat other people.
How are test samples collected?
Collecting test samples for SARS-CoV-2 – a respiratory virus found in the nose and throat – usually requires a trained person who inserts a long swab way back into each nostril for about 15 seconds. It can also be done with a sputum sample and possibly saliva. Testing saliva, if it is as sensitive as a swab test, is of course less invasive and less expensive, as it requires fewer experienced people and no swabs, and easier to repeat.
Testing antibodies requires a blood sample.
Do we really need mass COVID-19 testing now?
Austria has successfully limited the spread of disease. But we aren’t safe, and no, the pandemic isn’t over.
We need to do widespread COVID-19 testing to help prevent a second wave of outbreaks. We need a plan including COVID-19 surveillance, contact tracing, quarantine, and immediate social distancing to stop transmission of the virus. We need to continue vigilantly counting active and past cases of COVID-19 to move eventually toward herd immunity and end the pandemic with the lowest possible loss of life.