Why is qPCR used for COVID-19 testing worldwide?

What are its technical advantages?

With the routinization of COVID-19 testing, qPCR, a cutting-edge technology in molecular diagnostics, has been gradually universal. This technology has many technical advantages over the traditional PCR, making it the gold standard for COVID-19 testing worldwide. What are the advantages of qPCR that make it universally available and maintain its excellent reliability?

Advantages of qPCR

1. Low risk: the lid is only open twice in the whole process so the risk of laboratory contamination is small;

2. Simple operation: the operation is simpler compared to the tedious operation steps of mNGS, which makes it easier to promote;

3. Fast: amplified DNA is detected while the qPCR reaction is in progress, so it does not need to be detected separately (e.g. on sepharose) as in traditional PCR;

4. High efficiency: qPCR is considered to be a highly efficient method, and in conjunction with automated liquid handler workstations, it can process a large number of samples in a short time;

5. High sensitivity: qPCR is able to discriminate a 2-fold difference in the number of target DNA, and it can detect as low as only a few of initial DNA molecules. QPCR just needs as little as 1/1000th of the amount compared to PCR;

6. Wide range of quantification: it can quantify a wide range on several orders of magnitude;

7. Reproducibility: it is usually considered to be highly reproducible.

Applications of qPCR

Many people may have a basic understanding of qPCR only through COVID-19 testing, but its application can actually not be limited to COVID-19 testing. Due to the obvious technical advantages, qPCR has a wide range of applications. Since qPCR has a long enough history, various studies have proven its reliability and stability. Similarly, manufacturers of qPCR cyclers have developed supporting platforms, and suppliers of automated liquid handling equipment have developed automated solutions compatible with qPCR.

Most commonly, qPCR is used in molecular diagnostics, where it is slowly replacing traditional methods (microscopic images). It is used to detect, identify and quantify the microorganisms (bacteria, viruses and fungi) that cause diseases. With qPCR, manual labor is reduced. It allows the processing of a large number of samples in a short time (up to 384 or even 1536 reactions per run) and is an irreplaceable method in diagnostic laboratories. It must be noted, however, that the method only detects the presence of DNA or RNA of microorganisms, not their viability. Therefore, traditional microbiological techniques are still sometimes needed in conjunction with PCR. In addition, another very important application area of qPCR is gene expression studies, which can help us to understand various fields of biology, microbiology, medicine and other life sciences.