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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 onset of symptoms to day five, while SARS-CoV and MERS subsequently reach load; this could also be the reason why the kovida 19 pandemic is spreading more rapidly.
To date, evidence of the SARS-CoV-2 virus points to a nine-day infectious period pattern. Since the study only looks at confirmed cases, not those that may have been exposed, it cannot provide information on the length of the recommended quarantine.
Although viral loads appear to be similar between people infected with the SARS-CoV-2 coronavirus who develop symptoms and those who don’t, most studies suggest that asymptomatic individuals can shed the virus more quickly and be contagious 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, no live viruses that can cause infections were found in the samples collected nine days after the onset of symptoms, according to a review. systematics and a meta-analysis of three human coronaviruses, published in The Lancet Microbe.
98 studies
“The findings are consistent with contact research studies which suggest that most viral transmission events occur very early, especially in the first five days after symptoms appear, indicating the importance of self-isolation immediately after onset of symptoms, “says lead author, Dr. Muge Cevik. University of St. Andrews in the UK.
“We also need to raise awareness of the range of symptoms associated with the disease, including mild symptoms that may occur earlier in the infection than more pronounced ones, such as cough or fever.”
The researchers included 98 studies with five or more participants, cohort studies, and randomized retrospective studies; 79 of them 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 studies included in this systematic review were able to successfully isolate live viruses after the ninth day of symptoms in any type of sample.
Several studies have successfully isolated live viruses from stool samples, and the role of fecal-oral transmission for SARS-CoV-2 remains unclear.
“These results suggest that in clinical practice, it may not be necessary to repeat PCR tests to determine that the patient is no longer contagious,” says Dr. Cevik.
The highest viral load of the 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 10-14 days, respectively, seven to ten days after the onset of symptoms.
Asymptomatic cases
Only twelve studies reported asymptomatic individuals infected with the SARS-CoV-2 virus, and six of them also studied how quickly people excreted 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 excrete the viral material from the body more quickly,” says Dr. Cevik.
Several studies have found that people with an asymptomatic infection can get rid of the virus faster, suggesting that those without symptoms may be as contagious as those with symptoms early in the infection, but may be contagious 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
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