In a small group of patients with mild COVID-19, nasopharyngeal/oropharyngeal swabs collected during the first week of illness showed infectious virus but not after this period despite high detected rates of SARS-CoV-2 RNA from these sites.
The duration of viral shedding varies significantly and may depend on severity. Among 137 survivors of COVID-19, viral shedding based on testing of oropharyngeal samples ranged from 8-37 days.A different study found that repeated viral RNA tests using nasopharyngeal swabs were negative in 90% of cases among 21 patients with mild illness, whereas results were positive for longer durations in patients with severe COVID-19. These studies have all used PCR detection as a proxy for viral shedding.Investigating a cohort of patients who had prolonged PCR positivity, determined that infectious virus was not present.
Viral Shading of Covid attack -https://www.medscape.com/viewarticle/931898
DR JOSEPH--Please take a look at the link below:
https://www.medscape.com/answers/2500114-197467/what-is-the-duration-of-viral-shedding-in-persons-with-coronavirus-disease-2019-covid-19
Regards-
Viral Shading of Covid attack -https://www.medscape.com/viewarticle/931898
It is a very important question as it determines the duration of isolation for preventing spread
As correctly said, it varies with severity (defined by WHO) .
We have patients with prologed PCR positivity beyond ever 3 to 4 weeks, but no viral load, RNA or culture done to determine infectivity
There are factors related to the duration of the viral shedding and can be observed in the following research, which is entitled:
Factors associated with the duration of viral shedding in adults with COVID-19 outside of Wuhan, China: a retrospective cohort study
https://www.ijidonline.com/article/S1201-9712(20)30352-0/fulltext
Duration of viral shedding vary from person to person. Every person has different immunity power. It's the immunity of the body that's determine the viral shedding. Old age person are are at very high risk and symptoms appear very fast then the young aged people.
The duration of viral shedding varies significantly and may depend on severity. Among 137 survivors of COVID-19, viral shedding based on testing of oropharyngeal samples ranged from 8-37 days, with a median of 20 days. [40] A different study found that repeated viral RNA tests using nasopharyngeal swabs were negative in 90% of cases among 21 patients with mild illness, whereas results were positive for longer durations in patients with severe COVID-19. [41] In an evaluation of patients recovering from severe COVID-19, Zhou et al found a median shedding duration of 31 days (range, 18-48 days). [42] These studies have all used PCR detection as a proxy for viral shedding. The Korean CDC, investigating a cohort of patients who had prolonged PCR positivity, determined that infectious virus was not present.
Reji Joseph You also need to take into consideration fecal shedding.
That continues much longer even when nasopharyngeal swab has been negative.
However virus particles shed through GI tract may not be infectious
The validation tests carried out in Colombia found that from day 10 of symptoms, the probability of positive PCR results began to decrease.
https://www.revistainfectio.org/index.php/infectio/issue/view/103/showToc
The duration of viral shedding varies significantly and may depend on severity. Viral shedding based on testing of oropharyngeal samples ranged from 8-37 days, with a median of 20 days .
rt-pcr antigen testing. Can use CT (cycle threshold) value to assess the infectivity.
Value more than 35-safe, patient is no more infective to others... Less than 35 always carries risk of infection spread.
Dear Dr Joseph: The duration of viral shedding varies significantly and may depend on severity. Among 137 survivors of COVID-19, viral shedding based on testing of oropharyngeal samples ranged from 8-37 days, with a median of 20 days : https://www.medscape.com/answers/2500114-197467/what-is-the-duration-of-viral-shedding-in-persons-with-coronavirus-disease-2019-covid-19
Regards--
The duration of SARS-CoV-2 viral shedding also depends on age, and the viral shedding is reduced by antiviral treatment.
Article Factors associated with prolonged viral shedding and impact ...
At this time, we do not know if someone can be re-infected with COVID-19. Data to date show that a person who has had and recovered from COVID-19 may have low levels of virus in their bodies for up to 3 months after diagnosis. This means that if the person who has recovered from COVID-19 is retested within 3 months of initial infection, they may continue to have a positive test result, even though they are not spreading COVID-19.
https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html
Article Duration of viral shedding in asymptomatic or mild cases of ...
It depends entirely on the immune system status of that particular individual. Personally it is a case by case basis.
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