(Fighting New Coronary Pneumonia) Urumqi Center for Disease Control Analysis "Two cases of nucleic acid tests were negative and the third time was positive"
China News Service, Urumqi, August 14 (Reporter Sun Tingwen and Zhao Yamin) In response to "the first two nucleic acid test results were negative for a case, the third time it was positive and was diagnosed as a confirmed case", deputy of Urumqi CDC Director Wen Guoxin analyzed the above situation from two aspects at the 28th press conference on epidemic prevention and control held in Xinjiang on the 14th.
Wen Guoxin said that, on the one hand, this situation illustrates the complexity of the Urumqi epidemic. The epidemic spread quickly. Within the first 14 days, the number of confirmed cases and asymptomatic infections increased rapidly; There are many patients with symptomatic and asymptomatic infections, and some patients’ detoxification is relatively late, which makes prevention and control work more difficult. The incubation period of the new coronavirus is usually 3 to 7 days, which means that most people will get sick within 3 to 7 days after being infected with the virus, some people are less than 3 days, and some people are more than 7 days, but they are basically 14 days. During the incubation period of days, it needs to be detected repeatedly.
Wen Guoxin, deputy director of the Urumqi Center for Disease Control and Prevention, answered questions from reporters at the 28th press conference on epidemic prevention and control held in Xinjiang on the 14th. Photo by Zhao Yamin
On the other hand, Wen Guoxin analyzed that nucleic acid test results are affected by many factors. A positive nucleic acid test indicates that there is a virus at the sampling site, reflecting the state of infection. Two consecutive nucleic acid tests were negative, mainly due to two reasons: First, after the new coronavirus infection, the virus is mainly in the lungs, and the inflammation produced blocks the lung airways, the virus cannot be discharged temporarily, and the nasopharyngeal virus is rare. , It is difficult to collect the virus. The second is the change of the condition and the timing of sampling. The progress of the patient's condition is different, and the timing and time interval of sampling will also affect the test results and cause false negatives. Of course, it is also related to sampling operation level and specimen reagents.
Wen Guoxin stated that according to the "New Coronavirus Pneumonia Diagnosis and Treatment Plan (Trial Seventh Edition)", the interpretation of nucleic acid test results cannot rely solely on laboratory results, but must be combined with epidemiological history and clinical manifestations to make comprehensive judgments. If there is a clear epidemiological exposure history and clinical symptoms, one or two nucleic acid tests are negative, it cannot be simply determined as non-infected, it may be false negative, and repeated sampling and testing are required. If you have not been to a high-risk area where the new coronary pneumonia is prevalent, and if you have a history of contact with an infected person, and have no clinical symptoms such as fever or sore throat, the nucleic acid test result is negative, there is no need to worry about false negatives. (Finish)