Innovation in the detection technology of nasopharyngeal swab: clinical application and complete analysis of virus sampling

As a respiratory infectious disease with obvious seasonal characteristics, its accurate diagnosis directly affects clinical decision-making and infection control results. Based on the gold standard requirements of pathogenic testing, nasopharyngeal swab detection technology has become the first choice for influenza screening due to its unique advantages. This paper combines the perspective of clinical laboratory medicine and practical data of Grade A hospitals to systematically analyze the innovative value and operating specifications of swab detection technology.

1. Analysis of the clinical advantages of nasopharyngeal swab detection technology 1. A breakthrough in timeliness: The viral replication cycle and detection window phase match the active replication period of influenza virus in respiratory cilia epithelial cells (24–72 hours) is significantly earlier than the production of serum IGM antibodies. Swab nucleic acid testing can be performed through RT-PCR technology, and a positive result can be obtained within 18–24 hours after the onset of symptoms. According to the clinical research data of the Lancet in 2023, pharyngeal swab detection provides effective pathogenic evidence 2.8 days ahead of serological diagnosis, creating a therapeutic window for the early application of neuraminidase inhibitors.

2. The dual-optimal design of patient compliance and biosafety is compared with traditional nasal swab sampling (prone to sneezing reflex) and serum detection (requires venous puncture). Oropharyngeal swab sampling only requires three rotational wipes on the bilateral palatal arch and posterior pharyngeal wall. Data from our hospital in 2022-2023 showed that patients' acceptance of modified flocking swabs reached 94.3%, and the success rate of cooperation in the children group increased to 81.5%. The optimization of the sampling process reduces the aerosol production by 67%, significantly improving the occupational protection effect of medical staff.

3. Technical innovation of multi-pathogen synchronous detection The multi-PCR detection platform based on Tasman probe technology can perform synchronous screening of 16 respiratory pathogens on single swab samples. Taking the "Respiratory Infection Diagnostic Matrix" established by the Laboratory Department of our hospital as an example, this system integrates detection targets such as influenza A/B virus, respiratory syncytial virus and novel coronavirus, and compresses the 96-120-hour detection cycle required by the traditional culture method to complete within 4 hours.

4. Key points of quality control for accurate sampling 1. Time phase selection and dynamic monitoring of viral load The peak of virus shedding is concentrated 24–48 hours after the onset of symptoms. The sampling positive rate at this stage can reach 98.7% (CDC 2024 data). Special attention should be paid to the possibility of bimodal virus release curves in immunosuppressive patients, and it is recommended to perform secondary sampling verification within 72 hours. The sampling depth should ensure that the swab head contacts the pharyngeal crypt and the rotation force is controlled at 3–4 Newtons (equivalent to the touch feeling when pressing the tongue lightly).

5. The swabs collected after standardization of sample processing should be placed in the virus storage solution immediately, and the test must be completed within 2 hours when transported at 4℃. The laboratory should adopt internationally certified nucleic acid extraction kits to ensure that the minimum detection limit reaches 50 copies/mL. For special samples (such as blood secretions), a protease K pretreatment regimen is recommended to improve detection rate.

In the diagnosis and treatment standards of fever clinics, it is recommended that patients with fever symptoms complete nasopharyngeal swab sampling in the waiting area first.
Studies have shown that antipyretic and analgesic drugs may interfere with viral load testing. Data from a provincial hospital shows that early sampling can reduce the false negative rate by 18%. The detailed explanation of clinical operation specifications is as follows:

Standardized sampling operation procedures (including key quality control points): 1. Position preparation: Instruct the patient to maintain a 45° head-up position, fully expose the anatomy of the pharyngeal cavity by continuously making "ah" sounds 2. Accurate sampling: Use a flocked swab (recommended Mairekolin 93050D professional model) to cross the root of the tongue, apply appropriate pressure to rotate for 3 weeks at the bilateral tonsil crypt, and then wipe it longitudinally three times on the posterior pharyngeal wall 3. Sample treatment: Place the swab in the virus preservation solution within 15 seconds after sampling. When breaking the wipe rod, maintain a 30° inclination angle to prevent aerosol from spreading.

Common operating misunderstandings and solutions: - Consumables selection: Disable swabs containing calcium alginate (PCR verification will inhibit 40% amplification efficiency), and it is recommended to use polyester fiber flocking swabs - Transportation specifications: Laboratory data show that when the sample transportation temperature is > 8℃, the hourly degradation rate of viral RNA reaches 1.7%. The use of Mairecolin VTM storage solution can maintain normal temperature transportation stability for 21 days - Aging control: sampling and testing must be ensured to be completed within 4℃ environment within 2 hours, and freezing of -70℃ is recommended to not exceed 168 hours.

Key points of construction of the third-level quality control system: Pre-processing stage: Configure an intelligent temperature control sampling box (built-in temperature recording module). After implementation of a certain Grade A hospital, the sample pass rate increased to 98.6% detection stage: Introduce RNAS P as an internal reference gene (a study shows that the false negative rate can be reduced from 12.6% to 4.3%) Results interpretation: For patients with low immune function, it is recommended to use hypersensitivity detection technology (the lower limit of detection can reach 50 copies/mL)

Extended clinical value: Modern molecular diagnostic technology has elevated nasopharyngeal swab detection into a core means for the prevention and control of respiratory infectious diseases. The laboratory department needs to conduct regular sampling standardized training (it is recommended to simulate operational assessment every quarter), and a decision-making system that links symptoms-test-treatment should be established in clinical practice. The latest guidelines point out that antigen testing combined with nucleic acid testing can increase the accuracy of influenza diagnosis to 96.8%.

The latest data from the National Health Commission in 2023 shows that standardized nasopharyngeal swab sampling can increase the sensitivity of virus detection by 23%. Medical institutions at all levels should strictly follow the operating specifications of the "Expert Consensus on Respiratory Virus Detection (2023 Edition)" and focus on optimizing the swab insertion angle (45° to the hard palate) and retention time (at least 30 seconds). Clinical studies have shown that the detection rate of influenza A virus can be increased by 19.6 percentage points compared with traditional oropharyngeal sampling. Experts particularly emphasized that qualified virus testing requires the sample storage temperature (2-8℃) and the transportation time (within 4 hours). This move has been verified by the Grade A institutions such as Peking Union Medical College Hospital to reduce the false negative rate to below 5%.