What You Should Do Before and After a PCR Test


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As you may have read in our previous articles, there are strict protocols to abide if we want to travel by air; one of which is to provide a PCR (widely known as rapid) test result stating that you are non-reactive to the mischievous C-19.

Failing to provide this single document will deny you access to your flight, even if you have paid for it. In this article, we are going to give you some information on what you have to do before and after taking a PCR test.

When a communicable disease outbreak begins, the ideal response from public health is to begin early and rapid testing. This leads to quick identification/tracing of cases, quick treatment and immediate isolation to avoid the spread of this disease. Early testing also helps to identify high risk contacts; anyone who came into contact with infected people. So, they too can be quickly treated to reduce the intensity of the spread.

Early testing is crucial to treat, isolate or hospitalize people who are infected; depending upon severity of infection. Testing is an important stage in the bigger public health picture for alleviating efforts, helping investigators, spread and contagiousness of the disease and characterize the prevalence.

The long-term testing strategy for COVID-19 must be based on the network of public and accredited private labs sourcing testing consumables from suppliers, whose quality has been vetted by central government agencies.

The main type of tests being used to detect the COVID19 are RT PCR, Antibody Testing and Antigen Testing. Some are more reliable than others; no single test is 100 per cent accurate. There are significant differences between them; in the way they work, but also their advantages and limitations, which are unique to each.

Currently, diagnosis of active infection is done with Reverse transcriptase polymerase Chain Reaction; RT-PCR test, the gold standard.  The virus is made up of a genetic material called RNA. When the virus enters host cells it uses RNA to replicate itself. So, it’s a direct test for detecting COVID -19 viral particles from nasopharyngeal and oropharyngeal swabs collected and transported via Viral Transport medium (VTM).

The RT-PCR test can only tell whether the person has live or very recently dead virus in their body at the time of sample collection. The likelihood of detecting the virus depends on collection methods, severity of infection and how much time has passed since infection. RT PCR tests are accurate but with high TAT and cost, it requires sophisticated equipment and unidirectional settings, trained personnel to run the tests.

Besides this, Serology tests play an important role for patient care and are crucial for the management and surveillance of the disease. These tests offer insight into the virus’s incidence within populations, including symptomatic or asymptomatic infections. They are important in determining the full scope of the disease, engaging the pandemic, surveillance and rebuilding mutual confidence.

Potentially detect immunity in COVID-19 recovered individuals. These tests identify patients with solving/resolved infections. Potentially detect immunity in individuals allowing them to continue their routines and possibly avoid unnecessary quarantine.

PCR testing needs extracted RNA (genetic material) from swabs. RNA extraction is process which comprises of lysis, binding and washing steps; with incorporation of Internal control(IC). This IC is guaranty of proper RNA extraction and should be read at the time of result interpretation along with other Quality control (QC). Extraction can be done manually, by semi-automated/fully automated instruments.

After extraction; addition of enzymes and primers and probes specific for covid-19 (designed in such a way that it will bind and amplify only & only Covid-19 specific genes) mixed with RNA in particular combination. This procedure also can be performed manually or automated with the help of liquid handler robotic arm systems. PCR uses this RNA for amplification.

The first step in the testing process is to convert the viral RNA into DNA using the enzyme reverse transcriptase so name RT PCR. Once this is done chemicals are used to amplify Covid-19 specific sequence so it can be read by the PCR instrument; Thermal Cycler and with precise software. PCR consists of three steps denaturation, annealing and elongation with exact number of cycles along with specific temperature.

By setting up the threshold results can be analyzed and reported as RNA Detected or Not Detected. This overall series of procedure takes 4-5 hrs.

Follow these instructions before taking a PCR Test:

  1. Do not eat, drink or brush your teeth 30 minutes before you take the test.
  2. Wear a cloth mask, keep your windows up and stay in your vehicle.
  3. Try to do a self quarantine of at least 14 days to minimiza the chance of getting or spreading the virus.

Then, afterwards,  these are the things that you should do:

  1. Since this test takes relatively shorter time to reach a result, there will be some waiting to do. While you wait, don’t take off your mask and maintain a distance of minimum 6 feet from other people.
  2. When the result comes and it’s non-reactive, then congratulations, you can go back to your day doing whatever you need to do that day. Still, the use of a mask is really effectibe to ward off viruses if you need to be around strangers. Keep them on whenever you find yourself in a crowd.
  3. When the result comes back.and it’s reactive, usually you will need a proper swab test. So use your mask and find out how you can get one, and then go home and lock yourself in for at least 14 days. Keep a log of your health progress, and take another PCR test after 14 days.

There you are, some info on what you should do before and after  PCR Test. Good luck and stay healthy!