Apparently nasal swabs are accurate certainly with a runny nose and they are easy to do with less risk to the provider . With instructions even from a government site a person can swab themselves and have the specimen collected for testing . There is research into having self testing home kits which would be great for workers in the aged care sector in particular . Good to know about testing and PPE on Futher updates . For Emergeny care with more ill patients in particular .
We are currently doing nasal swabs PCR to screen for Covid-19 but we are in the dark as to the sensitivity and specificity of such test. Does anyone have that information?
From Mel: It is almost impossible to find this information - best guess data is 75% sensitive - probably pretty specific as PCR virus studies usually are. There is no current gold standard that is the problem...in China some people clearly with the disease (clinical and radiological) tested negative initially - then later positive. one study (only available as abstract) said up to 50% false positive in low risk patients - but this is hard to believe.
Thanks for the info! A false-positive rate of 50% would not be hard to believe if we test a low-risk population (such as patients that have simple URIs and no risk factors for exposure) Let's say the test has a 99% specificity and you test a population where only 1 in a 1000 have the disease. That means if you test a 1000 people there would be only true positive and 10 false positive.
If a patient has a runny nose and the pcr kit is good hard to believe false positive is high and it is the false negative rate that would be really important also . A protocol is to get a respiratory viral panel and if the is say influenza or rhino virus turns up Covid 19 unlikely . -Read an article by an American geriatric fellow on the AGS discussion site who attended the infectious disease association of California winter symposium on the 3rd March 2020 -co-infection with other viruses is less than or equal to 2 % . -Dr Pyria Mendiratta in this article in AGS Forum also noted a dual phase clinical picture in the virus in serious cases a catarrhal phase of eight days then shortness of breath and pneumonitis so unlike the "sudden" influenza . -Trials with the anti retrovirals might then start in the catarrhal phase . -With respect to testing at the Alfred Hospital Melbourne Australia patients are doing their own swabs nasal and throat if they are mild cases of runny nose scratchy throat . -Self test nasal swabs under instruction will save a lot of time for health care workers and there seems a catarrhal phase of days . -With respect to intubation it will have to be the more skilled intubators in the full PPE with helmet shield if vision good which you could clean with diluted bleach or with the PAPR respirator . -
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Ian L. - March 6, 2020 7:39 PM
Apparently nasal swabs are accurate certainly with a runny nose and they are easy to do with less risk to the provider .
With instructions even from a government site a person can swab themselves and have the specimen collected for testing .
There is research into having self testing home kits which would be great for workers in the aged care sector in particular .
Good to know about testing and PPE on Futher updates .
For Emergeny care with more ill patients in particular .
Steve U., M.D. - March 10, 2020 2:01 PM
We are currently doing nasal swabs PCR to screen for Covid-19 but we are in the dark as to the sensitivity and specificity of such test. Does anyone have that information?
Anand S. - March 10, 2020 2:30 PM
From Mel: It is almost impossible to find this information - best guess data is 75% sensitive - probably pretty specific as PCR virus studies usually are. There is no current gold standard that is the problem...in China some people clearly with the disease (clinical and radiological) tested negative initially - then later positive. one study (only available as abstract) said up to 50% false positive in low risk patients - but this is hard to believe.
Anand S. - March 10, 2020 2:31 PM
https://pubs.rsna.org/doi/pdf/10.1148/radiol.2020200642
Mel H. - March 10, 2020 2:32 PM
Some References on this Steve:
https://pubs.rsna.org/doi/pdf/10.1148/radiol.2020200642
https://genome.cshlp.org/content/3/3/S18
Steve U., M.D. - March 11, 2020 11:16 AM
Thanks for the info! A false-positive rate of 50% would not be hard to believe if we test a low-risk population (such as patients that have simple URIs and no risk factors for exposure)
Let's say the test has a 99% specificity and you test a population where only 1 in a 1000 have the disease. That means if you test a 1000 people there would be only true positive and 10 false positive.
Ian L. - March 11, 2020 6:31 PM
If a patient has a runny nose and the pcr kit is good hard to believe false positive is high and it is the false negative rate that would be really important also . A protocol is to get a respiratory viral panel and if the is say influenza or rhino virus turns up Covid 19 unlikely . -Read an article by an American geriatric fellow on the AGS discussion site who attended the infectious disease association of California winter symposium on the 3rd March 2020 -co-infection with other viruses is less than or equal to 2 % . -Dr Pyria Mendiratta in this article in AGS Forum also noted a dual phase clinical picture in the virus in serious cases a catarrhal phase of eight days then shortness of breath and pneumonitis so unlike the "sudden" influenza . -Trials with the anti retrovirals might then start in the catarrhal phase . -With respect to testing at the Alfred Hospital Melbourne Australia patients are doing their own swabs nasal and throat if they are mild cases of runny nose scratchy throat . -Self test nasal swabs under instruction will save a lot of time for health care workers and there seems a catarrhal phase of days . -With respect to intubation it will have to be the more skilled intubators in the full PPE with helmet shield if vision good which you could clean with diluted bleach or with the PAPR respirator . -