“Sputum” results?Nucleic acid testing without “poke” line?
Repeated rounds of nucleic acid tests are being carried out in high-risk areas.Nucleic acid testing, the need to use swab in the pharynx repeatedly scraping, many people get “poke” many times.Some netizens have noticed that nucleic acid testing can be done through sputum testing in the COVID-19 Diagnosis and Treatment Protocol (Trial Ninth Edition).If “expectoration” also can give a result, can not get “poke”?So where is the test sample from more effective?Is it going to work?Science and Technology Daily reporter exclusively interviewed peng Niancai, an expert in the field of nucleic acid testing, professor of Xi ‘an Jiaotong University and founder of Tianlong Technology.”No matter what part of the sample is selected, as long as the nucleic acid can be obtained from it, the enrichment, purification and amplification of nucleic acid can detect whether there is a virus in it, and then reflect whether a person carries a virus, it is a qualified sample.For novel Coronavirus cases of respiratory transmission, throat, nose, anal, sputum and alveolar irrigation fluids can all be valid samples, Peng told Science and Technology Daily.In the case of pharyngeal swabs, in addition to obtaining pharyngeal secretions, enough virus-coated epithelial cells are removed.Sputum not only contains mucus secretions from bronchial mucosal epithelium, but also exfoliated mucosal epithelial cells and inflammatory cells, etc. These exfoliated cells of infected persons will carry viruses and can be detected positive after nucleic acid extraction.In addition, different sampling sites often have different representativeness.Some experts say that nasopharyngeal swabs represent upper respiratory tract infection, sputum represents lower respiratory tract infection, and anal swabs represent the body’s nucleic acid load.For example, it has been found clinically that some confirmed cases only have digestive tract symptoms, and respiratory tract tests may miss detection.Therefore, in some special cases, samples from different parts can complement and confirm each other.Sputum has a long history as a test specimen. “In the early stage of the epidemic two years ago, the Novel Coronavirus mainly caused lung inflammation, so nucleic acid tests were performed on alveolar lavage fluids.”As the scientific knowledge of novel coronavirus cases, such as the isolation of live virus in the stool of an infected person, suggests that the virus can also be detected in anal swabs, the number of test samples has gradually increased, peng said.Science and Technology Daily reporters found that the COVID-19 Diagnosis and Treatment Protocol (Trial Fifth Edition) generally classified samples into respiratory specimens and blood specimens.It was not until the sixth edition that respiratory specimens were divided into nasopharyngeal swabs, sputum and other lower respiratory secretions. Moreover, in order to improve the positive rate of nucleic acid test, it was suggested to collect sputum as much as possible, and collect lower respiratory secretions from patients with endotracheal intubation, and send the specimens for examination as soon as possible.It can be seen that for the novel Coronavirus test at the time, sputum test is superior to nasopharyngeal swab test, helping to reduce the false negative rate of nucleic acid test.Sputum test is not necessarily better “Nucleic acid test sampling is like ‘cutting bean sprouts’, with the course of infection and viral load are related to the timing and place of’ bean sprouts’, the ‘scissors’, can be detected positive or negative.”Therefore, the scissors should be cut in the right place in order to obtain effective samples, Peng said.”As people became more aware of the Omicron variant, they found that it infected the upper respiratory tract more.In theory, a sample of the upper respiratory tract selected for the detection of the Omicron variant would yield a positive rate for viral nucleic acid testing.”Therefore, whether sputum as a lower respiratory tract sample or nasopharyngeal swab has a higher detection rate and the highest detection rate in the days after infection is still needed to be further studied, Peng said.Specific guidelines are presented in the ninth edition of the Guidelines.In addition, for large-scale screening, the optimal sampling method should not only be noninvasive, convenient and have a high detection rate, but also be convenient for collection, avoid contact, and avoid cross-infection caused by aerosol formation.The data showed that the methods of collecting sputum samples included natural expectoration, trachea puncture and aspiration, and bronchoscopy extraction.Some methods are complicated and painful.Natural expectoration is also more complicated than swab collection. It is necessary to gargle with water several times to cough up sputum deep in the trachea, which is left in glass, plastic cups or wax coated paper boxes, so it is not convenient for further collection and detection.Therefore, nucleic acid detection through the collection of pharyngeal swabs is more conducive to standardized sampling of the whole process.In order to ensure the safety, effectiveness and standardization of nucleic acid testing, Wang Guiqiang, director of the Infectious diseases Department of Peking University First Hospital, advised the public not to eat within two hours before nucleic acid testing to avoid vomiting and nausea during the sampling process at the joint Prevention and control mechanism of The State Council on April 6.No water, no gum, and no alcohol for 30 minutes.Source: Science and Technology Daily