The viral load of the SARS-CoV-2 coronavirus appears to peak in the upper respiratory tract early in the course of the disease, from the onset of symptoms to day five, while SARS-CoV and MERS reach a later load ; this could also be the reason why the kovida 19 pandemic is spreading faster.
To date, evidence of the SARS-CoV-2 virus shows a pattern of a nine-day infectious period. Because the study only examines confirmed cases, not those that may have been exposed, it cannot provide insight into the recommended duration of quarantine.
Although viral loads appear to be similar between people infected with SARS-CoV-2 coronavirus who develop symptoms and those who do not, most studies suggest that asymptomatic individuals may expel the virus more quickly and become infectious for less time.
Although the genetic material of the SARS-CoV-2 virus can still be detected in respiratory or stool samples even after a few weeks, live virus that can cause infection was not detected in samples collected nine days after the onset of symptoms. after a systematic review and meta-analysis of three. human coronavirus, published in The Lancet Microbe.
“The findings are consistent with contact finding studies that suggest that most viral transmission events occur very early, especially during the first five days of symptoms, indicating the importance of self-isolation in immediately after the onset of symptoms, “says lead author Dr. Muv Cevik. University of St. Andrews in the UK.
“We also need to raise public awareness of the range of symptoms associated with the disease, including mild symptoms that may occur earlier in the infection than those that are more pronounced, such as cough or fever. “
The researchers included 98 studies with five or more participants, cohort studies, and retrospective randomized trials; 79 focused on SARS-CoV-2, eight on SARS-CoV and 11 on MERS-CoV infection.
With the help of respiratory samples, the viable virus multiplied in the first week of the disease. On the other hand, no study included in this systematic review successfully isolated a live virus after the ninth day of symptoms in any type of sample.
Several studies have successfully isolated live virus from stool samples, and the role of oral-fecal transmission for SARS-CoV-2 remains unclear.
“These findings suggest that PCR testing may not need to be repeated in clinical practice to determine that the patient is no longer infectious,” said Dr. Cevik.
The highest viral load of SARS-CoV-2 RNA coronavirus was detected early in the course of the disease, when symptoms appear or before the fifth day of symptoms. In contrast, viral loads in SARS and MERS reached a maximum of ten to 14 days, respectively, seven to ten days after symptom onset.
Only twelve studies report asymptomatic individuals infected with the SARS-CoV-2 virus, and six also investigated how quickly people expelled viral material from their bodies.
“Although viral RNA loads appear to be generally similar in people with and without symptoms, several studies suggest that asymptomatic individuals may expel viral material from the body more quickly,” said Dr. Cevik.
Several studies have found that people with asymptomatic infection can get rid of the virus more quickly, suggesting that those without symptoms may be just as infectious as those with symptoms at the start of the infection, but can be infectious for a shorter time.
The study was conducted by researchers from the Universities of St Andrews, Edinburgh and Glasgow, as well as hospitals in Edinburgh, Vishawa and Naples.
Source: B92.net, Tportal.hr