COVID-19 testing: Which is more accurate?
Amidst the numerous medical tests available to track down infectious viruses, the globe
still struggles to combat the pandemic as cases are immensely increasing due to the prevalence of
low cost tests with inefficient accuracy.
According to the US Food and Drug Administration (FDA), there are 2 categories in
COVID-19 testing; Diagnostic test and Antibody test. Diagnostic test includes RT PCR test and
rapid test. In a report from the Centers for Disease Control and Prevention (CDC), rapid tests had
an 80% accuracy rate for those who showed COVID-19 symptoms but are more prone to falsenegative and false-positive results. While RT PCR tests are nearly 100% accurate but take a lot
of time. Antibody test however, only tracks for antibodies and not active viral infection.
“Testing makes the enemy visible,” said Dr. Emily Volk, president-elect of the College of
American Pathologists (CAP). Eversince the strict community quarantine ceased, people are
getting the hang of enjoying their life through the new normal. People travel more, enjoy clear
and pristine water from vacations, and celebrate occasions with their loved ones. However, the
virus doesn’t take a break and could always infect anyone. That's why medical protocols such as
testing are needed to eradicate the pervasive invisible killer.
In certain countries, like Germany, testing is mandatory and free of charge, in the
Philippines however, people have to pay for their own expenses at various prices. Prices depend
on the accuracy rate of the test and the testing center or laboratory. People settle more on pocket
friendly and inaccurate tests, sometimes forged documents just to comply with the protocol’s
need. Added to that problem is the inadequacy of information and lack of awareness that the
society faces. Thus, extensive information is needed to fuel the urgency of this battle.
Molecular test ( aka RT PCR Test or swab test)
This type of diagnostic test looks for signs if you currently have active infection.
According to the US FDA, it detects the virus’s genetic material using lab techniques and
is considered the “gold standard” of tests due to its near perfect accuracy. It is highly
recommended by experts for its 97% to 100% ability to accurately track down the Sars-Cov-2
virus that causes the disease.
Moreover, it is commonly known as the swab test for a 3 inches specialized swab is
inserted from the back of someone's nose for about 10 to 15 seconds to scrape for mucus as a
sample. The mucus then undergoes RT PCR test, short for Reverse Transcription Polymerase
Chain Reaction. From the swab, the sample is analyzed in a laboratory called amplification, the
action of making multiple copies of a gene or DNA sequence. The sample contains an RNA, a
single strand genetic material, covered with fatty membrane and spike proteins in which are the
key factor to the process. To detect the virus, since a single material couldn’t effectively detect it,
RNA is extracted and is duplicated to create DNA through a process called Reverse
Transcription, then undergoes Polymerase Chain Reaction, to rapidly make millions and billions
of copies of the DNA sample enough to accurately identify the virus.
This test is highly recommended by experts for its sensitivity and accurateness. It would
take about 48 to 72 hours for the result to come out depending on the capacity of the laboratory
and the amount of people tested.
Antigen Test (aka rapid test)
Antigen test is another molecular test that uses genetic material to detect the virus. It's
pretty much the same with the swab test, however, it's easy and quicker (that's why it's called
rapid) and thus, not quite accurate. Journal Nature points out in a recent article that it is
commonly used for large numbers of people, like airports on local transportation that requires
bare minimum time of usage. Usually the results come out more or less an hour.
A sample is taken from the person’s nose using a swab, compared to the RT PCR test that
uses RNA, an antigen test uses the spike proteins as a tool for detection. Antigens are foreign
substances that evokes the immune response of the body. As the virus secretes antigens, the virus
can also be distinguished. If you test positive, it’s probably correct. However, it only offers 80%
accuracy rate and is more prone to false negative for it is more likely to miss out active infections
but still, a crucial tool for tracking down viruses. False positive cases will only waste human and
available resources, adding a lot of unnecessary loads and hassle.
The price usually ranges from 2,000php to 4,000php which is a negotiable price for its
accuracy rate.
Antibody Test ( aka Serology Test)
This is a diagnostic test of the blood serum. It is important to remember that this test does
not detect active virus infection, it just looks for antibodies that the body produces once it
encounters the coronavirus. Antibodies are proteins your immune system produces to fight off a
foreign invader. This just tells if you’ve been infected at some point in the past even if that
occurred months ago. However, the results are a critical help in the continuous development of
treatments and solutions in the current setting.
The test works as a medical expert takes a blood sample via a finger prick or a blood
draw from a vein in a person’s arm. The results would only take seconds to hours. To determine,
there are two antibodies produced by the body after an infection: IgM (Immunoglobulin M) and
IgG (Immunoglobulin G). In 3 to 10 days, IgM level will increase and then tapers off while IgG
shows in about two weeks and sticks around for much longer, in normal circumstances could be
years. That's why antibody testing isn’t recommended until at least 14 days after the start of
symptoms, says the Mayo Clinic. This adds to the difficulty in making a consistently accurate
antibody test. You can be early in the infection for IgM or between IgM or IgG being detected or
you can't be detected at all.
Antibody testing has a role to play in the current pandemic because it can provide
information on the prevalence of the infection in the population and the frequency of
asymptomatic infection, per the FDA. It usually ranges from 500php to 1,500php. This test is
highly not recommended for detecting active viruses.
Testing is a crucial step to track the amount of people exposed to the virus and to control
it. If symptoms persist, seek help and get tested for you are not only putting your life’s stake but
others as well. In this time of the pandemic, remember that honesty and discipline is the best low
cost medicine you can offer to prevent further spreading. #