Researchers have found in a new study of patients in China that covid-19 virus persists longer and peaks later in the respiratory tissue of patients with severe disease compared with patients with mild disease.The study has been published in The BMJ.

They further found that duration of SARS-CoV-2 is significantly longer in stool samples than in respiratory and serum samples, highlighting the need to strengthen the management of stool samples in the prevention and control of the epidemic.Therefore it is advisable that in order to prevent transmission of SARS-CoV-2 it is necessary to carry out strict management during each stage of severe disease

Researchers estimated viral loads in more than 3,000 samples collected from 96 patients with covid-19 infection admitted to a hospital in Zhejiang province, China between 19 January and 20 March 2020.

The viral load is the number of viral particles present in an infected patient. In general, the higher the viral load the more virus particles a patient can release ("shed") into their environment when they exhale or cough.

The researchers found that the median duration of virus in stool (22 days) was significantly longer than in respiratory (18 days) and blood samples (16 days). They also found that the median duration of virus in the respiratory samples of patients with severe disease (21 days) was significantly longer than in patients with mild disease (14 days).

In the mild group, the viral loads peaked in respiratory samples in the second week from disease onset, whereas viral load continued to be high during the third week in the severe group.

Virus duration was longer in patients older than 60 years and in men.

They point to some study limitations, such as the relatively small number of participants, that may have affected the accuracy of their results. However, they say their findings show that the virus persists longer with higher load and peaks later in the respiratory tissue of patients with severe disease.

The findings also highlight the importance of carrying out strict management during each stage of severe disease to help prevent and control the epidemic, they conclude.

Journal: The BMJ

For further reference log on to:

:https://www.bmj.com/content/369/bmj.m1443