Chinanews client, Beijing, September 13 (Peng Ningling) On the 12th, 22 new local confirmed cases were confirmed in Fujian. This wave of epidemics that began in Putian has now spread to Xiamen and Quanzhou.
According to previous Putian reports, Lin Moumou, who was suspected of being the source of the epidemic, had been in the country for 38 days when he was diagnosed, and the results of 9 nucleic acid tests were negative, and 1 serum test was also negative.
This information brought the topic of the virus' "ultra-long incubation period" back into focus.
So, how to calculate the "ultra-long incubation period"?
Do you need to adjust prevention and control measures?
On September 12, medical staff sampled nucleic acid for students of Fuzhou University.
Photo by Fan Xinchen
The diagnosis was only 38 days after entering the country
. What's new in Delta?
In the official notification on September 10, Lin Moumou (38 years old, Singaporean immigrants, parents of students) who was suspected of the source of the epidemic was introduced.
The investigation found that Lin Moumou was a returnee from overseas. He entered Xiamen Airport from Singapore on Xiamen Airlines flight MF852 on August 4, and was quarantined at a designated hotel in Xiamen for 14 days, and then transferred to Xianyou County on August 19 point-to-point. The centralized isolation point continues to be centralized isolation.
According to Fujian Province’s epidemic prevention and control measures, Lin started a 7-day home health surveillance on August 26 after completing a “14+7” day of centralized isolation.
According to Ling Longmei, director of the Putian Center for Disease Control and Prevention, imported cases from outside Singapore were quarantined for 21 days. During this period, 9 nucleic acid tests were negative and 1 serum test was negative. On September 10, the nucleic acid test results were positive, and the virus incubation period Longer.
In addition, Putian also introduced that the specimens of the epidemic-related cases have been sent to the Provincial Center for Disease Control and Prevention for genetic sequencing, and the results were preliminarily determined to be the Delta strain.
Nucleic acid has not been detected positive for 38 days and 9 times after entering China. Is this inconsistent with the characteristics of the Delta strain that the Delta strain has a short incubation period and rapid onset?
Does it mean new changes in the virus?
Recently, a public health expert stated in an interview with the media that this situation cannot be completely ruled out, but it is necessary to first rule out other possibilities such as false negatives caused by testing reagents, testing operations, and sampling.
Peng Zhiyong, director of the Department of Critical Care Medicine, Zhongnan Hospital of Wuhan University, told the Global Times that according to previous observations, about 95% to 99% of infected persons can be detected during the set centralized quarantine observation period, but they cannot be avoided. A few extreme cases appeared.
"The general characteristics of the Delta strain currently exhibited are that one is strong infectivity, and the other is high viral load and high viral load. In fact, it also means that it is easy to be screened out. At present, it seems that Delta The Ta virus strain is actually easier to find than the previous strains.” Peng Zhiyong said.
Medical staff sampled nucleic acid for students of Fuzhou University.
Photo by Fan Xinchen
Is the virus too cunning, or is there loopholes in prevention and control?
Regarding the "extra-long incubation period", Lin Moumou of Putian City is indeed not the first case.
As early as the beginning of this year, there were also multiple rounds of nucleic acid tests that turned from negative to positive in multiple COVID-19 cases in multiple places: a case in Dalian showed positive results in 11 nucleic acid tests, and a few close contacts in Shunyi, Beijing were isolated after 14 days All positive tests have caused concern.
In recent times, in addition to Putian, Fujian, there has also been a case of a nucleic acid test in Guangzhou, Guangdong.
According to the news on the official website of the Guangzhou Municipal Health Commission on September 10, Guangzhou has added a new positive case of new coronavirus nucleic acid from a close contact.
The case began to undergo centralized isolation medical observation on September 4. During the isolation period, the nucleic acid test results of the new coronavirus were all negative, and the nucleic acid test was positive on September 10.
According to a report from China Broadcasting Corporation on January 17 this year, Feng Zijian, deputy director of the China Centers for Disease Control and Prevention, analyzed that “(nucleic acid testing changes from negative to positive). Diversity. There may be rare cases of long incubation period, there may be problems with the sensitivity of nucleic acid detection reagents when close contacts are released from isolation, and there may be close contacts infected during isolation. Various situations May exist."
How to calculate the incubation period of the new coronavirus?
In February last year, Cai Weiping, an expert in the treatment team of the Guangdong New Coronary Pneumonia Prevention and Control Headquarters and director of the Infectious Diseases Center of the Eighth People's Hospital of Guangzhou City, once introduced that the "incubation period" refers to the time from a patient's infection with the virus to the appearance of the first symptoms, rather than a nucleic acid test. The result is calculated as positive; only those with symptoms can define the "incubation period".
In answering whether there is an "extra-long incubation period", Cai Weiping said that it was because some patients had milder symptoms and were ignored.
He believes that it is difficult to say whether there is an "extra-long incubation period".
It is worth mentioning that in February last year, the team of Academician Zhong Nanshan published a paper in the top international medical journal "New England Journal of Medicine". The study found that among 1,099 patients with new coronavirus infections, severe and non-severe patients with new coronary pneumonia Each patient has an incubation period of up to 24 days.
In this regard, Academician Zhong Nanshan said that the 24-day incubation period is only an exception, and it is not surprising that there are always exceptions.
Guangzhou Baiyun Airport.
All inbound flights from Fujian to Guangzhou are included in key control. Photo by Lin Yican
Should the prevention and control strategy be adjusted?
Regarding the "extra-long incubation period" cases that appeared in the Putian epidemic, how to protect them is still the most concerned issue.
Relevant experts said that the "extra-long incubation period" is not common and cannot be regarded as a common situation. Strengthening vaccination and personal daily protection are still the top priorities.
For example, regarding the prevention and control of Delta, at present, prevention and control experts generally believe that the existing vaccines still have a good preventive and protective effect on the Delta strain, which can reduce the risk of virus transmission in the population and reduce the spread of infected persons. , Effectively reduce the incidence of severe illness and mortality after infection.
In response to the hidden danger of "ultra-long incubation period," some regions are also exploring and upgrading prevention and control measures.
In January of this year, in order to effectively deal with the risk of transmission of infected persons with a long incubation period and the risk of imported epidemics at home and abroad, Beijing adjusted and strengthened the prevention and control measures for people entering Beijing from home and abroad, and implemented classifications for people entering Beijing from abroad and all close contacts in Beijing. "14+7+7" management measures.
So, how long is the quarantine period for insurance?
Many experts have analyzed that extending the time of centralized isolation can reduce the risk of virus transmission to a certain extent, but as the virus continues to mutate, it is still impossible to rule out the extreme situation of long-term virus carriers.
Some experts also believe that the next step should be to optimize the development of better antibody detection reagents. In addition, it is not enough for the prevention and control of the new crown epidemic to only highlight "isolated persons". International cargo transportation also exposes great risks. At the same time, it is necessary to strengthen Entry testing and restriction of animals from epidemic areas carrying the new coronavirus.
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