Understanding why PCR tests & rapid antigen tests yield different results for COVID
The world is on the verge to settle for an ‘endemic’ as after two years of battling with the virus, the end doesn’t seem to be any near. Endemic precisely means that the pandemic will not end, the virus will keep circulating, but almost all humanity will develop enough antibodies that there will be no criticality. It may sound better than a pandemic. and it will be the efforts of millions working day and night for two long years to study, understand, and build tools to detect and mitigate the virus.
One of the major tools that helped the world control these lethal coronaviruses was testing equipment. Without these, there can be no fight. Two of the major tests that are widely used to detect SARS-CoV-2 are the PCR test and Rapid Antigen Test in Delhi, Mumbai, and almost all India. While PCR is a molecular-based test, the other is a very effective Antigen test that provides rapid results.
However, the global reports are emerging that both tests yield different results on many occasions, the question remains, why is it so? And which test to be taken up for better accuracy? This article aims to answer these questions, but first, let’s understand each of these two tests.
PCR Tests
It is an extremely accurate test. It requires a fully functional lab and a few special types of equipment like a PCR heating machine. The test may take 6-12 hours to provide the results.
The first step is to get the Nasal or throat swab of the patient. The next step is to amplify the genetic material to even conquer a small number of coronavirus genes in the patient’s sample. It is done through a technique called Polymerase Chain Reaction (PCR). When the target sample is mixed with the enzyme solution, it converts the RNA present into DNA. Then again, the DNA is mixed with another solution called polymerase and heated, resulting in the DNA breaking into two single-strand DNAs. Now, when the temperature is kept down, additional complementing DNA called primer is added that stuck to single-strand DNA and makes many copies of it. The main work of this primer is to copy the coronavirus DNA.
Subsequently, with the help of laboratory machines, this process is repeated at least 30 to 40 times, and billions of such DNA copies are amplified. These amplified pieces contain fluorescent dye that can only be read and captured by a special machine. It helps indicate the presence of SARS-CoV-2 clearly.
With such a sophisticated process, PCR tests are proved to be highly sensitive and accurate to detect coronaviruses. These tests received the gold standard and continue to be used by laboratories and hospitals worldwide today. Taking more time to give results and requiring a trained lab technician are the only two factors of PCR tests that pose a challenge.
Rapid Antigen Test
A Rapid Antigen test in Delhi and other cities of India is a much easier test and faster in nature and can be even be conducted by the common man, but it is less sensitive than PCR tests. However, the USP of the Rapid Antigen test remains in its ability to provide rapid results, sometimes within 15 minutes. The need for quick testing at the onset of a new variant has increased the demand for antigen tests.
Antigens are substances that make the body produce an immune response and trigger the developing antibodies. The antigen test equipment contains lab-developed antibodies that search for antigens from the target coronavirus in the sample.
The first step is to administer the sample to a solution of salt and soap. It will help break the cells and other particles. Following this, the solution is applied to a test strip (containing antibodies) that is provided with the kit. A colored line will appear on the test strip if the sample contains SARS-CoV-2 strains as the antibodies will bind to the antigens.
Major Difference Between The Two That Lead to Varied Results
Rapid Antigen tests in Delhi and worldwide are easy to conduct. Even a non-trained person can use the kit. These are economically priced, can be bought easily through pharmacy, and provides results in no time. However, the major issue with the Antigen test, which makes them less accurate than the PCR test is that these tests only provide the best results when the viral load in the sample is heavy. As antigen test methodology doesn’t amplify the targeted viral DNA, it will produce results when there will be enough viral antigen is present in the sample for antibodies to indicate the presence of the virus.
Thus, antigen tests can miss the early stage infection when the patient may be asymptomatic or has a less viral load in the nose, mouth, throat, etc. Get yourself tested – https://spicehealth.com/book-rapid-antigen-test-in-delhi/
Today, renowned diagnostic labs are conducting the covid test on a daily basis, giving both options to choose from. SpiceHealth, for instance, a leading diagnostic lab provides quality and affordable healthcare in the country. It offers RT-PCR and Rapid Antigen Test in Delhi, Gurgaon, Jaipur, and many other cities in India at the lowest prices.
