Questions tagged [test]

This tag should be used for questions about Biomedical tests used in diagnosis of health conditions.

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14 views

How are the FPR and FNR estimated for a new diagnostic test?

Let's consider a case of a test for presence/absence of a viral infection. When we have certainty as to whether a specific individual is carrying the virus, it is easy to estimate the False Positive ...
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1answer
22 views

How often is SARS-CoV-2 RNA detected in plasma, for patients otherwise diagnosed?

I'm curious how sensitive the earliest retrospective diagnoses for SARS-CoV-2 (in China) might be. According to the paper which put the earliest case to December 1, 2019 that retrospective diagnosis ...
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Can hospitals test a sting to see if it was caused by a wasp or a bee?

I would like to know if a typical urban hospital is able to test if a sting was by a bee or a wasp. If so, is that something that is routinely done for people who are allergic to one or the other ...
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142 views

For how long does one test positive for COVID-19 after being infected with COVID-19?

I read on https://www.thehealthy.com/infectious-disease/how-long-can-you-test-positive-for-covid/ (mirror): According to the CDC, you can test positive up to three months after exposure even though ...
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Are false negative/positive results of COVID tests independent probabilistic events?

The gist of it Though there are many types of Covid tests, I think none have 100% sensitivity or specificity. What I would like to know is if the event of getting, e.g., a false negative on two tests ...
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11 views

What is the recommended diet before a parasite stool test?

They usually need 3 stool samples within a period of 10 days. It's usually done for 3 consecutive days. The recommendation I find online about the recommended diet before parasite stool test ...
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13 views

How does the Control Zone on Rapid Covid Tests work?

How does the Control Zone on Rapid Covid Tests work? The Test Zone reacts to covid cells, from what I understand. But to what reacts to Control Zone?
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45 views

Which is the best test to confirm a Lidocaine allergy?

As per my study, there are two tests which are performed to confirm/dispute a Lidocaine allergy. Patch test Intradermal Test Which is the most conclusive of the above? Are there any other tests?
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Covid-19: what's (usually) the probability of getting a negative PCR result conditioned on getting a positive antigen test result first?

It's been pointed out to me that most studies comparing antigen with PCR tests either consider these as independent tests carried out over the whole sample (and report concordance/discordance that way,...
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109 views

Antigen vs PCR test

In the Czech Republic there is now mandatory testing for factory employees. Anecdotally I am now being told by people I am acquainted with, who run medium sized firms here, that their employees are ...
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What's the difference between rt-PCR COVID-19 test using different lengths of nose swab?

I read: Our nose swabs only enter the nose ½ inch, not all the way up the nostril, ensuring no pain or damage. A few months ago, I had a COVID-19 test with a nose swabs that looked like ~5cm. What's ...
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50 views

Covid19 Rapid serological tests and Vaccine

Let's say that once I'm vaccinated I try the rapid serological test and the result is negative. My question is: let's admit that the reliability of the test is 100%; does it mean that the vaccine didn'...
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Is there a simple way to quantify viral content beeing exhaled by a person potentially independent of the specific virus type?

As far as I have understood it, persons who have contacted virusses (that are to a substantial part transmitted through the air, such as covid-19) tend to be only or most strong infectuous during a ...
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Can an individual who has had a covid-19 vaccination test positive and is that a problem?

Can an individual who has had a covid-19 vaccination test positive and is that a problem? Up to now and for some time to come, testing has been important to help control the spread of this disease. ...
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82 views

Do having multiple COVID tests decrease the chance of a false negative? [closed]

With my work we're required to get frequent COVID tests. Sometimes it happens we get COVID tested twice before the first day of work. So for example if I'm working Saturday I may get tested the ...
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31 views

why isn't this finger stick antibody test (for covid) in more common use?

I had some concerns about going to the dentist, because dental treatment involves a lot of aerosolized droplets and seems like a good way to get a high dose of covid. My dentist's office (in Manhattan)...
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53 views

Are COVID-19 patients infectious even if test results are negative?

With Covid-19, are people infectious in the first days after infection before they test positive on a Covid test? I have learned that Covid-19 tests are ineffective in the first few days after being ...
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47 views

Does the stool test for Helicobacter pylori show only acute infections?

There are four options when being tested for Helicobacter pylori - blood test, stool test, breath test and scope test. (Helicobacter pylori (H. pylori) infection) Scope test is definitely the most ...
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Who's RNA does the rRT-PCR test for SARS-CoV-2 target?

The official guide for laboratory testing for coronavirus disease in suspected human cases by the WHO explains the procedure for testing a sample. On page two it states that the test is based on ...
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3answers
433 views

What is the principal goal in pooled COVID-19 testing?

Pooled testing for COVID-19 is being considered as a method to ramp up testing Stat News. Apparently this is being considered by the White House coronavirus team. It's not clear to me what the goal of ...
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119 views

Has China announced any results from their massive (new) COVID-19 testing program in Wuhan?

About 10 days ago China announced a plan to test the entire population (~11 million) of Wuhan. And more recently they've announced testing over 1 million per day in the city. But have any results been ...
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67 views

Why does CDC's RT-PCR protocol for Covid-19 use the N gene, but the Charite one the E gene and RdRp?

The Charite protocol mentioned among other things that Of note, the N gene assay also performed well but was not subjected to intensive further validation because it was slightly less sensitive. ...
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What's the margin of error for the estimate on the percentage of people infected with latent tuberculosis?

According to a 2011 (news) article in Science More than a third of the world's population is estimated to be infected with Mycobacterium tuberculosis. Most people's immune system can keep the ...
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62 views

Is there a possibility of transmission of COVID-19 during sample collection process?

Is there a possibility of transmission of COVID-19 during sample collection process from safety kits worn by sample collecting person to the suspected infected person whose sample is being collected? ...
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82 views

Can the specificity of a COVID-19 antibody test be improved by testing twice?

My question is fairly simple: There is a COVID-19 antibody test with a worst-case specificity of 98%, meaning that it yields potentially up to 2% false positives. While that number is not bad it is ...
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1answer
42 views

How often is a Ct of 30 (or more) using the Charité protocol a false positive for Covid-19?

A French case report that has received widespread media attention suggests (actually stated in pretty strong terms in the paper) that Covid-19 was already spreading in France in December 2019. (In ...
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1answer
66 views

Is there a graph over time of Covid-19 test positivity rate in the US?

Back in mid-April some commentary/news was that the US was not doing enough testing as evidenced by the test positivity rate: America’s 20 percent positivity rate is disquieting. The U.S. did almost ...
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32 views

COVID-19: Is it possible to use the specimen collected through swabs for multiple tests

I am an engineer and currently doing some modeling of COVID-19 testing from a math perspective. I was reading through COVID-19 articles related to testing and I had the following doubt: If a ...
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1answer
128 views

Are there methods available to determine ongoing cell damage in Covid-19 survivors?

It took years for many of those first infected with Hepatitis-C, to learn that it was destroying their livers. It took years for those with HIV to learn their immune systems were being destroyed. Is ...
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53 views

Is there a colorblindness test for non-verbal children?

The colorblindness tests that I have seen have all relied on getting a verbal answer from the test subject. Examples are "What number do you see in this picture?". Most people can follow a test ...
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50 views

Can having other coronaviruses like HCoV-OC43 give positive results when testing for SARS-CoV-2? [closed]

Is it possible that a person having coronaviruses other than SARS-CoV-2 test positive for SARS-CoV-2 in rapid (antibody testing kits) as well as RT PCR tests? Searching around the internet didn't ...
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1answer
132 views

Why isn't saliva sampling used when sampling for the presence of respiratory diseases?

Previously I've asked a question focused on COVID-19: Why did countries initially presume that detecting COVID-19 requires a deep nasal swab? @Fizz provided the following response: So clearly it was ...
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47 views

Ratio of PCR to antibodies positive Covid-19 tests in studies outside USA?

CNN reported: Two studies involving antibody blood tests in California -- one in Los Angeles County and the other in Santa Clara County -- so far have suggested that the number of people already ...
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Have cases of Covid-19 virus "reactivation" been noticed in countries besides China and South Korea?

April 10 news: South Korean officials on Friday reported 91 patients thought cleared of the new coronavirus had tested positive again. [...] Jeong Eun-kyeong, director of the Korea Centers for ...
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238 views

Why were so many Covid-19 negative tests among close contacts of the early Chinese cases?

In an ECDC report from Jan 17, it is said that In China, 763 close contacts have been identified and monitored. Of these, 644 have completed the observation period, while 119 remain under medical ...
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198 views

Are false positives from Cellex’s Coronavirus antibody test systemic?

The FDA just approved the first antibody test for the Coronavirus, made by Cellex. The test has a significant false positive rate though (see here). Now for a lot of tests, false positives can be ...
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2answers
378 views

Is South Korea doing "random" testing to combat covid-19 epidemic?

It is well-known that South-Korea has developed a powerful system of drive-through testing allowing them to test hundreds of thousands of person in the past two months. I was wondering whether the ...
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53 views

Why is the US not implementing large scale random Covid-19 testing to isolate asymptomatic people? [closed]

For this question, we will define surveillance as large scale random Covid-19 testing. It is my understanding that: surveillance enables the sorting of asymptomatic patients to be immediately ...
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894 views

Is it possible that COVID-19 virus exist in a human body, but be absent from samples taken from nose and back of throat?

As specified in this link, COVID-19 tests start with taking samples from the nose or back or throat of people. Based on growth rate of this disease, I thought what if those samples are not positive (...
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1answer
35 views

What is the best protocol and criteria or policy for COVID-19 novel coronavirus testing?

What is the best protocol and criteria or policy for COVID-19 novel coronavirus testing? During early U.S. infections, the criteria have been stringent due to limited test availability. As tests ...
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158 views

Can the capacity for COVID-19 tests be amplified by testing multiple samples mixed together and testing each only if positive?

If I understand it right, the following steps are to be taken into account: Taking the sample: for the proposed method more samples would have to be taken. Transporting the sample: more samples ...
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1answer
258 views

Is there a way to test for covid 19 after recovery?

I had symptoms that could have been corona symptoms last week. Unfortunately the testing capacity in my country (Germany) is not sufficient to test every person with symptoms at the moment, so only ...
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1answer
62 views

Which tests for Coronavirus/COVID19 are available and why seem they be so different?

Lately I'm reading about the good Coronavirus-Tests in South Korea, the faulty tests in the USA and the tests in Indonesia which are according to some Singapore newspapers not even working. I wonder ...
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310 views

Why are people with COVID-19 symptoms being denied tests in the US?

I have heard several times now, from both people I personally know and from others who have posted their stories online that they do not qualify for COVID-19 testing. From the stories I have heard, ...
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29 views

Pandemic: what is the term for the phenomenon of diffusion of tests and the spreading of the virus itself?

Context: from the "discovery" of the virus to its spreading Before the discovery of sars-2 people died from sars-1, flu or pneumonia. On the one hand, we have a new, previously unknown virus that is ...
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87 views

Having tested positive for COVID-19, will future tests be positive?

The World Health Organization indicates the COVID-19 genome is detected in assays. Once a patient tests positive, is there any reason not to expect that future instances of the same assay will result ...
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45 views

Tilt table test and beta blockers

Is tilt table test indicative with beta blockers for dysautonomia diagnosis? Or is it require drug withdrawal?
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170 views

Is there any figure about the accuracy of COVID-19 tests? [duplicate]

Recently I saw the local media (Romania) presenting a case that was initially considered COVID-19 positive and two subsequent tests led to negative results. As far as I know no official bothered to ...
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115 views

How do they test COVID-19 in drive-thru labs?

I've read that SARS-CoV-2 virus which causes COVID-19 disease can be tested with RT-qPCR.[1] It seems a somewhat lengthy procedure. Then it's unclear to me: how do they test the virus in drive-...
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Technology prospects for genome sequencing at home and data protection

Ever since the end of the Human Genome project we have been witnessing the steady advance of genome sequencing technology and the decline of the price required to perform it. This lead to the advent ...