Currently, the nucleic acid test (RT-PCR) in patients is the “gold standard” for the diagnosis of new coronary pneumonia. However, the viral dynamics in patients with new coronary pneumonia are still not fully determined. On February 24th, local time, a team of researchers from the Beijing CENTER for Disease Control and Prevention and the University of Hong Kong published a newsletter in the top medical journal, The Lancet Infectious Disease. Different types of clinical samples collected from 82 patients diagnosed at different stages of infection were reported to try to answer this question.
(Original title: Hong Kong University Pan Liwen Willow Knife Published: New Crown Patients Died With High Sputum Virus Load)
Journalist He Liping
The study showed that the viral load of patients with neo-coronary pneumonia peaked at an early stage (5-6 days after symptoms), which was different from the peak time of SARS (on the 10th day of symptoms). The sputum virus load in patients with new crowns is higher than that of a pharynx swab. At the same time, the patient may already be contagious before symptoms appear. The study also found that a new corona patient died with a high sputum virus load.
The study was led by Leo L M Poon, a professor at the School of Public Health at the University of Hong Kong, and Quanyi Wang, director of the Beijing Center for Disease Control and Prevention. Pan Liwen is an expert in the field of emerging viruses, he has been involved in the biology of RNA virus, the molecular diagnosis of infectious diseases, etc. , the main scope of research for influenza viruses and coronaviruses. In 2003, sars outbreak, Pan Liwen was one of the first scholars to discover that atypical pneumonia was caused by a new type of coronavirus and first cracked the first sequence of atypical pneumonia coronavirus.
Two patients in Beijing were admitted to hospital and collected samples, including pharynx, sputum, urine and feces, on a daily basis. Patient sittivation of patients No. 1 was collected on the 3-12 days after the onset of the disease, and the collection time for patients no. 2 was 4-15 days after the onset of the disease. These samples were confirmed by N gene-specific quantitative RT-PCR testing.
The viral load in the pharynx and sputum samples peaked around 5-6 days after the onset of the disease, ranging from 10 to 4-10 to 7 copies/ml (Figure A, B). The change of this virus load pattern is obviously different from that of SARS patients, SARS patients generally reach a peak of viral load about 10 days after onset. The viral load of sputum samples was generally higher than that of pharynx swab swabs.
Neither patient’s urine or feces samples were detected in the new coronavirus RNA.
Dynamic changes in viral load in patients with new coronavirus infection. The average viral load (A) of continuous virus in patient swabs and sputum samples in patient no. 1, the average viral load (B) of continuous virus in patients with pharynx swabs and sputum samples in patients No. 2, pharynx swabs and sputum samples (B), pharynx samples with different stages of infection, sputum samples virus load (C), and studies on the correlation between viral load and sputum sample viral load (D) in patients with different stages of infection
The team also studied respiratory samples from 80 other patients at different stages of infection, including nasal swabs (1), pharynx swabs (67) and sputum samples (42). The range of viral load is 641-1.34 x 10 x 11 copies/ml, the average viral load of the swallow swab is 7.99 x 10 x 4 copies/ml, the average viral load of sputum is 7.52 x 10 x 5 copies/ml (Figure C), and the only nasal swab (3rd day after onset) shows that the viral load is 1.69 x 10 x 5 /ml.
Overall, the authors say, the viral load was higher in the early stages of the disease.
The researchers found that samples taken in a patient who died on the eighth day of the onset of the disease showed a very high viral load of the sputum sample (1.34 x 10 x 11 copies/ml).
It is worth noting that two people who were closely monitored as a result of contact with new coronal patients tested positive for RT-PCR the day before the onset of the disease, indicating that the infected person was contagious before the symptoms developed.
In addition, in 17 of the 17 new cases of coronavirus infection (0-13 days of onset), stool samples from 9 patients showed RT-PCR positive. The authors caution that although the fecal virus load is lower than that of respiratory samples, 550-1.21 x 10 x 5 copies/ml, precautions should still be taken when processing faeces samples.