The COVID-19 virus is like a weird ghost. The fierceness in the early stage of the epidemic, the “resurrection” in the middle stage, and the “asymptomatic” in the later stage have always been elusive.
However, relevant experts told China Science News that behind these seemingly weird things, you can find evidence to explain the doubt.
After the recovery, the mystery of “Fuyang”
Why did some patients with COVID-19 experience “rejuvenation” after treatment?
In this regard, Wei Chunhua, the director of the Weifang Hospital in Shandong Weifang, who has just completed the task of supporting the Hanyang District Hospital in Wuhan, said in an interview with the China Science News that in fact, a considerable part of the patients are false “Fuyang” and “false yin”, and the patients are The “false negatives” caused by nucleic acid detection errors, the virus in the body has not been removed, but the nucleic acid detection was not detected before discharge.
Why was it not detected before the patient was discharged? Wei Chunhua explained that the first is the problem of the kit. Due to the violent outbreak of this epidemic, the demand for kits is large, and the relevant approvals are not strict.
According to national regulations, the COVID-19 virus kit, which is related to the detection of pathogenic pathogen antigens, antibodies and nucleic acids, belongs to the third category of in vitro diagnostic reagents, which is the highest review level in medical devices.
In view of the epidemic situation at that time, the drug regulatory department accelerated the approval process of the COVID-19 virus kit, which has been shortened to a few days from at least 2 to 3 years in the past. “In this case, the quality of the kit is definitely uneven.”
According to Chinese disease control experts, there are three main indicators for evaluating the quality of the kit: specificity, sensitivity and repeatability.
The most important of these three indicators is sensitivity, which is also the core of the quality difference of various kits.
Followed by sampling. Nucleic acid detection mainly collects pharyngeal swabs. The COVID-19 virus is mainly located in the lower respiratory tract such as the lungs, trachea, and bronchi, while the nasopharynx and oropharynx are in the upper respiratory tract.
There are some viruses in the upper respiratory tract in the early stage of the disease, and there are few in the late stage. There may be virus residues in the pharynx, but they may not be collected.
Finally, nucleic acid detection requires a basic amount of virus to be detected. Compared with the upper respiratory tract, the virus content in the lower respiratory tract is higher. Therefore, no matter how many times the test is performed, sampling from the upper respiratory tract may cause false negatives.
“‘Fuyang’ may also be a virus fragment or dead virus detected in the body, which does not mean that the patient has not been cured or the condition is repeated.”
Wei Chunhua said that “Fuyang” may also be intermittent detoxification. At the end of the disease period, the virus content is low, and the patient is likely not to have symptoms such as coughing or sneezing. At this time, whether it can cause infection is unknown. From the current observations, there have been no reports of cases of infection in Fuyang patients.
The confusion of “pneumonia” again
In the interview, Wei Yong, a doctor from Wuhan Hanyang Hospital and a doctor from Qingdao Sida Cardiology Hospital, provided the reporter with such a set of data. After reviewing 90 COVID-19 patients after 14 days, only one patient found fever, cough and pneumonia again symptom.
The patient was diagnosed with COVID-19 on January 26. After treatment, his clinical symptoms were relieved, and the nucleic acid test was twice negative. He was discharged on February 11 and reached the discharge standard. After discharge, he had no fever, cough and other discomforts.
On March 14, the patient developed fever, chest glass showed ground glass shadows, the total number of white blood cells was normal, the lymphocytes were at the lower limit of normal, and the nucleic acid test was negative, and the antibody test was IgM ±, IgG +.
Usually infected with virus, patients will produce IgM and IgG antibodies.
IgM antibodies are the earliest antibodies that appear after human infection with the virus. They are usually produced 3 to 5 days after infection, suggesting that a new infection has occurred and can be used for early diagnosis of infection; the disease disappears soon after recovery.
IgG antibodies are protective antibodies. They are produced two weeks after the infection of the virus and last a long time. They may be carried for life, indicating that the virus has been infected. The higher the IgG value, the more antibodies, and the stronger the resistance to viruses.
Both IgM and IgG antibodies are negative, indicating that there is no infection, or no antibody has been produced; both are positive, indicating that they have recently been infected and there are viruses in the body; IgM is negative and IgG is positive, indicating that the patient has produced antibodies during the rehabilitation period Is safe.
“From an immunological point of view, a decrease in IgM ± and an increase in IgG + indicate that the body’s protection against viral infection has occurred.”
Wei Yong said that after the COVID-19 patients are cured, the body’s immune function has not been fully restored, and it may be infected with other pathogens, such as other viral pneumonia. There is no evidence that this patient relapsed from COVID-19.
Fear of onset “asymptomatic”
For the asymptomatic infected person, Wu Zunyou, the chief expert in epidemiology of the Chinese Center for Disease Control and Prevention, provided a study conducted by the Ningbo Center for Disease Control and Prevention in the press conference of the Joint Prevention and Control Mechanism of the State Council.
The study shows that from the individual level, the transmission efficiency of asymptomatic infected persons is equivalent to 1/3 of the confirmed cases; from the group level, the cases transmitted by asymptomatic infected persons only account for 4.4% of the total number of cases.
“That is to say, the asymptomatic infected person has a relatively small contribution to the spread of the epidemic.”
Wu Zunyou said that the current measures can detect and control asymptomatic infected persons in a timely manner. It is very unlikely that the asymptomatic infected persons will cause epidemic epidemic and will not cause the spread of social level.
However, considering the current situation of asymptomatic infections in all parts of the country, consider the existence of such invisible infections in Hubei area. Support the medical staff of Wuhan and Qiu Bin, director of the Chinese medicine department of Weifang Hospital of Shandong Weifang, to support the 127 outbreaks of Hanyang Hospital. The results of the COVID-19 virus antibody test conducted by the frontline medical staff showed that there were 111 support members outside Wuhan and the nucleic acid test and antibody test were all negative; 16 local support members of a local medical institution in Wuhan had 3 COVID-19 virus antibody tests IgG was positive and nucleic acid was negative, and they were not diagnosed as COVID-19.
Qiu Bin said that according to this data, there are indeed asymptomatic infections in Hubei, and the local medical staff ratio of 3/16 cannot be underestimated. At present, the number of such personnel is worthy of attention.
In addition, whether COVID-19 patients are contagious after discharge is also of great concern to the community.
According to the research data of Professor Cao Bin of the Sino-Japanese Friendship Hospital, the average detoxification time of COVID-19 patients is 20 days, and the longest patient detoxification time is 37 days, while the average hospitalization time of this group of patients reaches 24 days.
At present, according to the discharge standards established by the state, patients need to continue to be isolated for 14 days after discharge.
Qiu Bin said that such a plan is relatively safe for patients returning home from hospital.
“We have reviewed the COVID-19 virus antibody test results of COVID-19 patients. Only 14 days after centralized isolation, only 5.62% of the patients showed positive IgM and IgG. Only one case of pneumonia occurred again 14 days after discharge. The possibility of later infection is very small. “Qiu Bin said.
Win the “prepared” battle
For the strange phenomenon of the COVID-19 virus, Wei Chunhua suggested that the epidemiological survey of serum antibodies should be started immediately in Wuhan and other severely affected areas in Hubei to screen out asymptomatic virus carriers and chronically infected persons, completely cut off the transmission route and eliminate hidden dangers.
For example, for people who are positive for COVID-19 virus IgM, check the nucleic acid and chest CT. If there are abnormalities, they must be admitted to the hospital. If there are no abnormalities, they must be concentrated and isolated to different sites. The nucleic acid test is negative for 3 times. isolation.
For the false negative phenomenon of nucleic acid detection, Wei Chunhua suggested that the discharge standard of COVID-19 patients should be strictly implemented. In addition to the complete absorption of acute inflammation and the negative of pharyngeal swabs for nucleic acid tests, anal swab tests can be added for 3 times. Only negative can be discharged.
In the interview, doctors Ping Maohua and Xie Xiangjiang of Wuhan Hanyang Hospital both stated that COVID-19 patients are unlikely to have COVID-19 re-occurrence after discharge, and the possibility of infection is not high. Do not discriminate against them.
And those medical staff who support Wuhan are less likely to be the source of infection. After 14 days of isolation, they can work and live normally.
In addition, the public should still pay attention to personal protection, not to be paralyzed, wear masks, wash hands frequently, do not party, and keep a distance.
“No matter how strange the COVID-19 virus is, I believe that with the joint efforts of the whole country, we will achieve the final victory!” Wei Chunhua said.