The novel coronavirus continues to spread around the world, with confirmed cases on six continents except for Antarctica. According to the latest data released by WHO, new cases of COVID 19 have been reported in more than 170 countries and regions in the world, more than 380,000 people have been infected by novel coronavirus, and the number is still growing.[8-9]Due to the outbreak has developed rapidly, there should be a rapid and effective method for timely diagnosis among patients with different degrees of clinical symptoms and suspected patients. The novel coronavirus RNA detection can provide direct evidence for diagnosis. according to “Guidelines for Diagnosis and Treatment of COVID-19(Version 7)” of the National Health Commission, suspected cases should be confirmed for either etiology or serology.1. Real-time fluorescent RT-PCR was used for cases with positive results of novel coronavirus nucleic acid detection. 2. Virus gene sequencing is highly homologous with known novel coronavirus.3. If the serum novel coronavirus-specific IgM antibody and IgG antibody were positive, the serum novel coronavirus-specific IgG antibody was 4 times or more higher in the recovery period than in the acute phase.[10] Serological test was added to the new version of guidelines for diagnosis and treatment. IgM antibodies produced by the infected people were mostly positive in 3-5 days after the infection, and IgG antibodies were generally acquired by the body immunity after recovery. In the laboratory, IgM and IgG antibody colloidal gold strip was used to detect the serum of a positive patient after recovery and discharge from the hospital. IgM and IgG antibody were still detected after the serum sample was diluted by 16 times, indicating that the patient was likely to infect others and still need to be isolated and observed for 14 days without interruption of detection. Real-time quantitative PCR is the best choice for detecting viral nucleic acid in the early stage of novel coronavirus infection (asymptomatic stage). Real-time fluorescent RT-PCR is for synchronous detection of novel coronavirus and influenza virus. The detection method has high sensitivity and specificity [11-12], and it can detect the same sample quickly and accurately at the same time, which may provide an important support for early clinical differentiation, early diagnosis and early treatment.
The laboratory tested more than 3000 samples for both novel coronavirus and Flu A/B virus, and it was found that no Flu A/B virus was detected in patients who were positive for the novel coronavirus, and no novel coronavirus was detected in patients who were positive for Flu A/B virus. This is not just a coincidence, but a reflection of clinical data. Based on current clinical data, there is no cross-infection between the novel coronavirus and Flue A/B. It has been verified in the laboratory that the novel coronavirus can be inactivated at 56℃ for 30 min. In this laboratory, all samples to be tested were inactivated at 60℃ for 40 min, so as to further protect the personnel for detection and avoid destructive effect on nucleic acid virus RNA. After the comparison on test results of nasopharyngeal swabs, sputum and anal swabs of positive patients, it was found that, for the same patient, the Ct value of the nucleic acid amplification curve of the anal swab was greater than the Ct value of the sputum, and the Ct value of the sputum was greater than the Ct value of the nasopharyngeal swab. It can be inferred that for an individual with samples of nasopharyngeal swab, sputum, and anal swab collected at the same time, the detection effect of anal swab was the best, followed by sputum, and then nasal and pharyngeal swab. However, clinically, the collection of anal swab is mostly limited by place. Although sputum samples are collected conveniently, many patients and the close contacts do not have sputum when they need to be collected, and they are often replaced by saliva, which affects the detection effect. The nose and pharynx samples were collected at the same time. Although the sampling was convenient, the virus bearing capacity of the nasopharynx was limited, the Ct value of the amplification curve was low, and omission was easy to occur. Therefore, it was necessary to adopt the plan of sampling and repeated detection on alternate days for suspected patients. At the same time, in the case of "negative converted to positive" after the patient was cured and discharged from the hospital, sampling and re-examination should be carried out evert two days until the nasopharyngeal swab, sputum and anal swab were completely negative for nucleic acid detection, and then regular monitoring should be conducted for a period of time.
We certify that this manuscript is original and has not been published and will not be submitted elsewhere for publication while being considered by Antonie van Leeuwenhoek. And the study is not split up into several parts to increase the quantity of submissions and submitted to various journals or to one journal over time. No data have been fabricated or manipulated (including images) to support my conclusions.
The submission has been received explicitly from all co-authors. And authors whose names appear on the submission have contributed sufficiently to the scientific work and therefore share collective responsibility and accountability for the results.
Conflict of Interest: The authors declare that they have no conflict of interest.
The manuscript does not contain experiments using animals and human performed by any of the authors.
Informed consent was obtained from all individual participants included in the study.