Saliva tests for Covid-19 will be faster, more effective: Dr Opas

[webfact]

Saliva tests for Covid-19 will be faster, more effective: Dr Opas

By The Nation

 

 

Testing saliva samples will not only cut down costs, but will also make efforts to curb the virus more effective, said Dr Opas Karnkawinpong, director-general of the Disease Control Department.

 

Dr Opas, who is also secretary of the National Communicable Diseases Committee, said saliva tests will be easier, faster and more economical, especially in places like factories. Also, he said, such proactive steps will help boost confidence in the business industry.

 

Though Covid-19 screening by testing oral and nasal swabs through the RT-PCR method is still being widely used, saliva tests are also 90 per cent effective. If the virus is detected in the saliva sample, then the patient can undergo an RT-PCR test, he said.

 

“Provinces, especially those where many migrant workers are employed, may consider conducting saliva tests,” Dr Opas said.

 

Source: https://www.nationthailand.com/news/30401053

 

 

-- © Copyright The Nation Thailand 2021-01-12

 

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[ThailandRyan]

That is very good information.  If they can reduce the cost of testing and roll it out Nationwide then Thailand may finally get an accurate picture of the virus infections in the country.  This is what many of us have been asking for with more testing in-line with the world.   Once they have an Idea then they can direct great responses to ridding the country of the Virus.

[Oxx]

By the sound of this, this is an antibody test, so does not (despite what the article says) detect the virus.  It's not going to be particularly accurate, and will give false positives for people who've previously been infected and recovered.  It will also only register a positive once an infected person has started making antibodies against the virus.  Not sure how helpful this really is going to be.

[ThailandRyan]

6 minutes ago, Oxx said:

By the sound of this, this is an antibody test, so does not (despite what the article says) detect the virus.  It's not going to be particularly accurate, and will give false positives for people who've previously been infected and recovered.  It will also only register a positive once an infected person has started making antibodies against the virus.  Not sure how helpful this really is going to be.

I believe it is the rapid test to determine if positive or not, and not an antibody test.  Possibly the same one they are using in Japan., and elsewhere.

Japan allows saliva-based tests to boost COVID-19 detection - CNA (channelnewsasia.com)

Edited January 11, 2021 by ThailandRyan

[Oxx]

33 minutes ago, ThailandRyan said:

I believe it is the rapid test to determine if positive or not, and not an antibody test

 

You may be right, but if that were the case, why would the article say

 

1 hour ago, webfact said:

Though Covid-19 screening by testing oral and nasal swabs through the RT-PCR method is still being widely used, saliva tests are also 90 per cent effective.

 

which suggests that the saliva test is not using a reverse transcription polymerase chain reaction.

 

And if the test were directly detecting the virus, why

 

1 hour ago, webfact said:

If the virus is detected in the saliva sample, then the patient can undergo an RT-PCR test

 

A further test would be unnecessary.

 

Anyway, shoddily written article.

[richard_smith237]

50 minutes ago, Oxx said:

By the sound of this, this is an antibody test, so does not (despite what the article says) detect the virus.  It's not going to be particularly accurate, and will give false positives for people who've previously been infected and recovered.  It will also only register a positive once an infected person has started making antibodies against the virus.  Not sure how helpful this really is going to be.

 

I too was a little confused about this test and am of the understanding that its an ‘antigen test’ rather than an ‘antibody’ test thus identifies the presence of Covid-19, albeit not with the same degree of accuracy of the a Covid-19 RT PCR test. 

 

Thus: The risk of false positives could see a nation ‘test itself into a panic’

 

An article in the Lancet (from September) suggest the percentage of false positive results in the UK could be high as 4% - thus 16,000 people out of 400,000 tested daily could false positives.

Of course, double checking and re-testing those who test positive will significantly reduces this number. 

 

Thus: testing and evaluating positive test numbers alone can easily be misleading - testing of those with symptoms, monitoring hospital admissions and serious cases as well as those who have died because of (not with) Covid-19 are far more accurate metrics by which to evaluate the true impact and spread of this disease. 

 

 

 

 

 

 

[RickBradford]

59 minutes ago, richard_smith237 said:

An article in the Lancet (from September) suggest the percentage of false positive results in the UK could be high as 4% - thus 16,000 people out of 400,000 tested daily could false positives.

Right. And if the true Covid infection rate were 1%, then 4000 of that sample would have the disease.

 

But with the false positive, they would be reporting 16,000 + 4000 = 20,000 positives in a single day, 5 times the actual figure. Cue immediate panic.

 

Even the CDC has warned about the problem of PCR tests and false positives. 

 

"Before testing a large proportion of asymptomatic workers without known or suspected exposure, employers are encouraged to have a plan in place for how they will modify operations based on test results and manage a higher risk of false positive results in a low prevalence population."

 

https://www.cdc.gov/coronavirus/2019-ncov/community/organizations/testing-non-healthcare-workplaces.html

[Sheryl]

I am not aware of any hospital or clinic offering saliva based antigen test in Thailand. Is anyone else?

[Moonlover]

5 hours ago, Oxx said:

By the sound of this, this is an antibody test, so does not (despite what the article says) detect the virus.  It's not going to be particularly accurate, and will give false positives for people who've previously been infected and recovered.  It will also only register a positive once an infected person has started making antibodies against the virus.  Not sure how helpful this really is going to be.

Antibodies are found in the blood and the lymph system. I think it unlikely that it would appear in the saliva.

[Natai Beach]

6 hours ago, ThailandRyan said:

This is what many of us have been asking for with more testing in-line with the world

who have you been asking? Did you get a response?

 So you now want to compare Thailand with the rest of the world.

 

Ok, Thailand were the very first country to test and find cases outside of China.
Back in January Covid is now known to have been in the USA and Europe by then but no testing was being done, with western leaders even advising citizens NOT to wear a mask and running around hospitals shaking everyone’s hand.
Because NOT wearing a mask was going to help how? It was just going to magically disappear, but bleach was also good. 
 

Currently in the USA deaths are running up to 4,000 per day and new daily infections 300,000+. 
About one in 15 people there have had or do have covid. 
The death rate per capital is even higher in the UK,  a full year after China notified the world of a new highly contagious virus.
 

Death rate in Thailand is just under one in a million. In the UK and USA it is more than 1,000 times that. 
More than 1000 times worse. 
 

Testing being done in Thailand from June to November showed zero positives. If they had of had positives, more testing would have been done under the test and trace system. 
The USA hasn’t gone a single day in that time without 50,000 plus positives. Even with it that testing it apparently isn’t helping much as last week had the highest positives ever and the highest deaths.

 

 

 

[TigerandDog]

9 hours ago, Oxx said:

By the sound of this, this is an antibody test, so does not (despite what the article says) detect the virus.  It's not going to be particularly accurate, and will give false positives for people who've previously been infected and recovered.  It will also only register a positive once an infected person has started making antibodies against the virus.  Not sure how helpful this really is going to be.

disagree with you saying it won't be particularly accurate. More and more countries are now using this testing method and they ALL say it is more accurate than the nasal and oral swabs.

[starky]

13 hours ago, ThailandRyan said:

That is very good information.  If they can reduce the cost of testing and roll it out Nationwide then Thailand may finally get an accurate picture of the virus infections in the country.  This is what many of us have been asking for with more testing in-line with the world.   Once they have an Idea then they can direct great responses to ridding the country of the Virus.

Here we go with the great Thailand covid conspiracy again. Show me one shred of any proof or evidence that you can provide that would show there are thousands (or whatever number you seem to think) of unidentified cases of covid in Thailand. And why these cases don't seem to end up in hospitals effect the healthcare system or transmit the virus further through the community.  And then give me a comparison of the USA and how many unidentified cases they have walking the streets in comparison to their testing regime.

 And if there was some great cover up why all of sudden would they admit to the recent outbreak? In line with your thinking surely they would just bury it with all the other cases they are apparently not telling us about.

Edited January 12, 2021 by starky

[KannikaP]

2 hours ago, TigerandDog said:

disagree with you saying it won't be particularly accurate. More and more countries are now using this testing method and they ALL say it is more accurate than the nasal and oral swabs.

Would an 'oral' test not pick up some saliva anyway?

[Oxx]

6 hours ago, Moonlover said:

Antibodies are found in the blood and the lymph system. I think it unlikely that it would appear in the saliva.

 

You are wrong.  See, for example "Persistence of serum and saliva antibody responses to SARS-CoV-2 spike antigens in COVID-19 patients".

https://immunology.sciencemag.org/content/5/52/eabe5511/tab-article-info

[Moonlover]

57 minutes ago, Oxx said:

 

You are wrong.  See, for example "Persistence of serum and saliva antibody responses to SARS-CoV-2 spike antigens in COVID-19 patients".

https://immunology.sciencemag.org/content/5/52/eabe5511/tab-article-info

Thanks. We live and learn.

[Rimmer]

A troll/indirect flame removed

[RickBradford]

1 hour ago, starky said:

Show me one shred of any proof or evidence that you can provide that would show there are thousands (or whatever number you seem to think) of unidentified cases of covid in Thailand. And why these cases don't seem to end up in hospitals effect the healthcare system or transmit the virus further through the community.

The reason that unidentified cases don't end up in hospitals or affect the healthcare system is that they don't get sick - they are asymptomatic. If they were getting sick, they would be going to clinics and hospitals, and getting tested.

 

As for transmission by asymptomatic individuals, the British Medical Journal wrote:

 

"The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms. A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission."

 

https://www.bmj.com/content/371/bmj.m4851

 

It would be a monumental waste of time trawling through the wider community trying to find people who had Covid at some time and didn't know it, having never got sick or been tested.

 

 

 

 

[Robin]

He is forgetting that the last thing that the Gov. wants is widespread Covid testing, as that might show here are more cases than thy want to know about.  Maybe more difficult to justify restrictions if it has not kept down Covid infections.

The easiest way to reduce the numbers of Covid patients is not to go looking for them, except among migrants.

[RickBradford]

27 minutes ago, Robin said:

The easiest way to reduce the numbers of Covid patients is not to go looking for them, except among migrants.

That's one way to reduce the number of Covid cases (rather than "patients").

 

You could combine that with not talking about "Covid deaths", since the definition of a "Covid death" varies so much from country to country, and is generally so vague as to be useless.

 

For example, the UK records a Covid death as a "death in a person with a laboratory-confirmed positive COVID-19 test and died within (equal to or less than) 28 days of the first positive specimen date."

 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/916035/RA_Technical_Summary_-_PHE_Data_Series_COVID_19_Deaths_20200812.pdf

 

With that rule, you could have a heart attack, be flattened by a bus, or knifed to death up to 4 weeks after a positive test, and still go down as a "Covid death".

 

The key metric is going to be the number of excess deaths in 2020 from all causes - known as "all-cause mortality". That will show clearly how much of an extra impact the arrival of Covid has had.

 

In some countries, such as Australia, this will be the safest year in overall mortality in a decade, the light death toll from Covid counterbalanced by lowered mortality from other causes - perhaps people are staying at home more, and engaging less in risky behaviour.

 

Countries such as Spain and the UK will show excess mortality near to 10% over the year (i.e. total number of deaths this year 10% above the average).

 

(Detailed data at https://www.mortality.org.)

 

In Thailand, Covid-badged deaths over the last year now stand at 67; I would be interested to see the lowered death total for the year on Thailand's roads caused by lockdowns and other restrictions.

 

 

Edited January 12, 2021 by RickBradford
Clarify

[cyril sneer]

2 hours ago, Robin said:

He is forgetting that the last thing that the Gov. wants is widespread Covid testing, as that might show here are more cases than thy want to know about.  Maybe more difficult to justify restrictions if it has not kept down Covid infections.

The easiest way to reduce the numbers of Covid patients is not to go looking for them, except among migrants.

Yes exactly

 

This is actually bad news for Thailand 

[Virt]

I really hope the develop a fast saliva test for both anti bodies and to test if positive or not, because that means two things. 

 

It's then suddenly very easy to convert those into cheaper home tests so people can periodically test themselves at home. 

 

People don't have to endure those nasty nose or throat swaps that is being done today. 

 

I also hope they develop cheap sticker urine tests for home testing if possible to test urine, so we just can take a

"pee and see"

[rabas]

4 hours ago, RickBradford said:

The reason that unidentified cases don't end up in hospitals or affect the healthcare system is that they don't get sick - they are asymptomatic. If they were getting sick, they would be going to clinics and hospitals, and getting tested.

 

As for transmission by asymptomatic individuals, the British Medical Journal wrote:

 

"The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms. A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission."

 

https://www.bmj.com/content/371/bmj.m4851

 

It would be a monumental waste of time trawling through the wider community trying to find people who had Covid at some time and didn't know it, having never got sick or been tested.

The great undetectable  sea of asymptomatic  covid-19 cases argument, again.

 

Asymptomatic when tested, does not mean an asymptomatic case. True asymptomatic cases average  17%-20% globally. That means 4 in 5 cases develop symptoms. The facts from the highest authorities.

 

NCBI: Diamond Princess as a controlled environment to measure true asymptomatic cases  March

"The estimated asymptomatic proportion was 17.9% (95% credible interval (CrI): 15.5–20.2%)."

 

Nature Journal:  What the data say about asymptomatic COVID infections Nov

"Now, evidence suggests that about one in five infected people will experience no symptoms, and they will transmit the virus to significantly fewer people .... But researchers are divided about whether asymptomatic infections are acting as a ‘silent driver’ of the pandemic."

 

They further explain.  "Research early in the pandemic suggested that the rate of asymptomatic infections could be as high as 81%. But a meta-analysis published last month, which included 13 studies involving 21,708 people, calculated the rate of asymptomatic presentation to be 17%."

Edited January 12, 2021 by rabas

[Scott]

Inflammatory post reported and removed.

 

[Sheryl]

12 hours ago, Virt said:

I really hope the develop a fast saliva test for both anti bodies and to test if positive or not, because that means two things. 

 

It's then suddenly very easy to convert those into cheaper home tests so people can periodically test themselves at home. 

 

People don't have to endure those nasty nose or throat swaps that is being done today. 

 

I also hope they develop cheap sticker urine tests for home testing if possible to test urine, so we just can take a

"pee and see"

The virus is seldom present in urine even in people with massive infection. There will never be a urien test.

 

Saliva is possible