Coronavirus Testing 101: A Complete Beginner’s Guide
Fever, runny nose, and sore throat – are these symptoms for a common cold or COVID-19? Without a lab test, we have no way to tell.
In March, the World Health Organization sent a simple message to policy makers around the world: “Test, test, test.”
Without mass testing, countries are fighting the war blindfolded. How can you win when you don’t even know where the invisible enemy is?
In this article, we are going to look at the why, the how, and the what’s coming next for coronavirus testing.
Why is Coronavirus Testing Important?
Countries around the globe have approached coronavirus testing in dramatically different ways.
For example, many people in the United States could not qualify for COVID-19 testing during the early days, and this slow response cost the country big time.
In contrast, countries like South Korea and Iceland tested a large proportion of its citizens, including those that showed no symptoms of COVID-19.
Therefore, how the pandemic pan out very much depends on how available testing is. The more cases identified and isolated, the slower the spread.
Current Lab Tests for Coronavirus
The current diagnostic tests for coronavirus are molecular tests that rely on a technology called the polymerase chain reaction (PCR). Thanks to rapid sequencing of the SARS-CoV-2 genome in early January, molecular tests based on genetic information were made quickly available. Now, they are being used worldwide to diagnose COVID-19 patients.
The test involves first taking a sample from the back of the throat using a cotton swab. The sample will then be sent to the lab for PCR, the method that will amplify a few copies of genetic material to millions or billions. This way, scientists can quickly tell if the sample contained known genes from the virus responsible for COVID-19.
The PCR reaction itself only takes several hours, but it could take a few days for labs to run the tests due to a demand that exceeds capacity.
The most concerning limitation of PCR-based tests is that performing the PCR reaction requires complex laboratory equipment and highly trained technicians. The tests are usually only conducted within medium to large hospital facilities.
Because of a lack of resources and technicians, many countries had to set strict testing criteria so that only people who are most likely to have the virus are tested. Sadly, this delay or lack of testing have proven disastrous.
In addition, for those that do get a test, there is also the problem of false negative results. This is when the test fails to detect the presence of viral genes and the patients walk away believing they don’t have the virus. Obviously, this can have dire consequences if these people go about their normal life in the community and spread the disease.
There are many reasons that can lead to a false negative result:
It depends on how much virus the person is shedding (through sneezing, coughing and other bodily functions), how the test was collected and whether it was done appropriately by someone used to collecting these swabs, and then how long it sat in transport.Priya Sampathkumar, Infectious Diseases Specialist, Mayo Clinic
Antibody Test vs Antigen Test
Apart from molecular tests, there are also immunoassays that detect specific immune proteins: the antigen and antibody tests.
Instead of taking swab samples, these tests require blood samples as immune molecules are more readily available in blood.
Compared to PCR-based tests, antigens and antibodies are more stable, making them less susceptible to damage during transport. As a result, these tests could help with the false negative problem with molecular tests.
However, a major difference is that immunoassays can detect both ongoing and past infections. They cannot tell if someone is currently infected or has recovered. Therefore, they are not suitable for early diagnosis of COVID-19 alone.
The antibody test is already in use to detect past infections and immunity levels in countries like the United States.
Since higher levels of antibodies in the blood usually means a higher immunity, the U.S. is using antibody tests to identify recovered patients who have high antibodies in their blood. A research study has shown that these survivors’ blood can effectively help other COVID-19 patients fight the infection.
The United Kingdom has also spent 3.5 million on developing antibody tests that can be used at home for many good reasons:
- Antibody tests should be cheaper to mass produce and use at home, thereby alleviating the burden on our healthcare system.
- They can identify people who need or do not need social distancing.
- They can form the basis of “immunity passport” and allow some people to return work.
- They can provide researchers with data regarding how the disease is spreading and how human immunity is evolving.
- They can identify doctors or nurses who are safe to work with COVID-19 patients.
For healthcare providers and policy makers, large-scale antibody test data can help in making public health decisions. For example, which geographical areas have low proportions of susceptible individuals and it’s safer to lift lockdown restrictions?
Antigen tests are not yet used for COVID-19, but they may also come in handy soon.
Unlike antibodies that only peak at least 9 days after the initial infection, antigens are likely detectable in patients’ sputum much earlier. Therefore, combining an antigen test with another molecular test may more accurately identify a positive COVID-19 case.
However, the major caveat of antigen tests is also a requirement of trained scientists and laboratory settings. The challenge remains to develop a simple but reliable test that can be done in clinics or homes.
Currently, over 50 such tests are in development and we will likely see them once the transmission of COVID-19 declines.
Home Coronavirus Test Kits
Developing home test kits are invaluable in rapid diagnosis without overwhelming the healthcare system. They could be the game changer in turning the tide around.
According to Public Health England, quick home test kits are set to be available very soon. These referred to the 3.5 million spending on antibody tests, however, the outcome is less promising than the policy makers had hoped.
Developing an antibody test good enough for home use is fraught with challenges. Prof Marion Koopmans, head of virology at the Erasmus University Medical Centre says: “Based on what I’ve seen so far I’d be hesitant to give you an immunity passport based on a rapid test result.” Her lab is currently evaluating more than 100 home antibody tests in the Netherlands.
Frequently Asked Questions Related to COVID-19 Testing
- What is the test for COVID-19? To determine if you are currently infected with COVID-19, a molecular test is completed in laboratories. This test is also more commonly known as the “swab test” as the test involves collecting a sample from the back of your throat via cotton swabs. Alternatively, antibody tests exist to test if you have had COVID-19 in the past.
- What happens when you get the coronavirus disease? A number of scenarios may happen. The vast majority of people have mild symptoms that look like a common cold. Some people don’t even know they’ve got the virus. Less than 3% of the people die from the disease, mostly those that are at a high risk to begin with. Here is a comprehensive and visually appealing science poster that explains it in more detail.
- Can antibiotics treat the coronavirus disease? No. As the name suggests, antibiotics are anti-bacteria. They do not work against viruses such as the coronavirus. In fact, taking antibiotics when there is no bacterial infection is not a good idea and it can kill your healthy gut bacteria. These bacteria are important for barrier functions, digestion, metabolism and immune system!
Bottom Line on Coronavirus Testing
It seems that with all doors shut, immunity testing may be a helpful way for us to ease our way out of the strict lockdown.
Researchers from around the globe are working around the clock to develop inexpensive diagnostic kits for home use. It is likely that we will see molecular, antigen and antibody test kits widely available eventually.
Currently, too many uncertainties remain:
- Are recovered patients immune to COVID-19? If so, for how long?
- What level of antibodies in the blood means that the person has developed immunity?
- Can people immune to reinfection themselves still spread the virus to others?
- How accurate and reliable are antibody test results?
- If the antibody test is done at how, what reliable authority can issue the passport? Will there be fraudulence?
What are your thoughts on coronavirus testing? Let us know in the comments.