When was the toxicity and infectivity of the COVID-19 virus strongest and when will it decrease? This is one of the most interesting core issues of COVID-19. Now, more and more research and clinical observations have answered this question.
The Hong Kong University research team analyzed 23 patients and found that the viral load in the patient’s saliva reached its peak during the first week of COVID-19 symptoms such as fever and cough, and then gradually decreased, but the tracheal attraction of the critically ill patient Objects, such as throat swabs, have no such tendency. The results were published in the latest issue of The Lancet Infectious Diseases. This shows that patients with COVID-19 are highly contagious when their symptoms are mild in the early stages of the disease. Therefore, patients should be quarantined immediately after detection of viral nucleic acid positive and symptoms, and need to be treated carefully, otherwise people who may be infected will be more many.
At the same time, COVID-19 virus RNA was detected in the saliva of about one-third of the 23 patients participating in the study for more than 20 days, and it could be detected even after clinical recovery, but their condition was not It must be more serious. This result also coincides with the fact that some patients in the Mainland were “rejuvenated” (a positive COVID-19 virus was detected after the cure) after being discharged from the hospital with a negative viral nucleic acid test. Based on this result, the researchers believe that the method of extracting saliva to detect viruses is more reliable than detecting nasal swabs and throat swabs to detect viral nucleic acids, and it can also reduce the discomfort when extracting nasal swabs and throat swabs.
This study also tells us that the viral load of COVID-19 virus during the first week of symptoms in patients is the largest and the most infectious. It is similar to the previous severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS). ) It is completely different. The infectivity of the latter two reaches its peak after 7 or even 10 days of the onset of the patient. Therefore, COVID-19 is obviously different from SARS and MERS in clinical and prevention.
数量 The number of patients participating in this study by the University of Hong Kong is not large and may not be statistically significant, but it reveals some signs of the development of COVID-19 after all. Combined with other clinical treatment experience and observations, it can be known that COVID-19 virus may exist in patients for a long time, but its load and toxicity have decreased over time.
Another study confirms this. The research team of Shenzhen Third People’s Hospital, National Infectious Diseases Clinical Medicine Research Center and other units conducted a follow-up of 262 patients with COVID-19 for at least 14 days, and found that there were 38 “Fuyang” patients, accounting for 14.5%. Patients with COFID-19 in “Fuyang” are relatively younger than patients with COVID-19 in “Fuyang”, and their condition was usually milder and improved faster. What’s more interesting is that although “Fuyang” patients may carry the COVID-19 virus, in this study, none of the close contacts with “Fuyang” patients were infected. This shows that over time, even if a patient has “Fuyang” and the virus is still in the body, the viral load, toxicity and infectivity have decreased.
这种 There are many reasons for this, both because of symptomatic treatment and because the body’s immune function is gradually strengthening. The enhancement of human resistance is also reflected in two aspects: First, about 10% of people are always asymptomatic, and some of them may never get sick, indicating that these people have a strong immune system. The second is that even if the virus is infected and symptoms occur, only about 10% of the patients are critically ill, and the dead are mainly elderly people with weak resistance, and these people have some basic diseases such as hypertension and cardiovascular Disease, cancer and diabetes.
Overall, in the first week after the symptoms of COVID-19, the virus load was the highest, the most toxic, and the most infectious, but over time, whether with or without treatment, the virus load would decrease and the toxicity And contagion will also decline. The reason is not only a medical effect, but also the role of the body’s immune awakening and resistance enhancement. This also shows that COVID-19 is a self-limiting disease. As long as symptomatic treatment is given, most patients can be cured.