Global Statistics

All countries
554,058,479
Confirmed
Updated on July 3, 2022 4:21 am
All countries
526,121,184
Recovered
Updated on July 3, 2022 4:21 am
All countries
6,360,834
Deaths
Updated on July 3, 2022 4:21 am

Global Statistics

All countries
554,058,479
Confirmed
Updated on July 3, 2022 4:21 am
All countries
526,121,184
Recovered
Updated on July 3, 2022 4:21 am
All countries
6,360,834
Deaths
Updated on July 3, 2022 4:21 am
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How Accurate Is The Saliva Covid Test

New 97% Accurate Covid Saliva Test Could Make Regular Testing Part Of Normal Life Researchers Say

New Saliva-Based COVID Antibody Test Is Highly Accurate, Johns Hopkins Study Says

Philippe LOPEZ / AFPTom BatemanReuters

An experimental saliva test that can diagnose a COVID-19 infection in minutes is nearly as accurate as gold-standard PCR tests, researchers believe.

The Parallel Amplified Saliva Rapid Point-of-care Test, known as PASPORT, identified the virus with 97 per cent accuracy during trials at a Singapore hospital earlier this year.

Unlike a PCR test, PASPORT does not require laboratory equipment or specialist technicians to produce a result. It also does away with invasive throat and nasal swabs, as it works by applying saliva directly to a testing kit.

“A reliable and painless saliva antigen test that is affordable and convenient to perform would encourage more to be tested, and more frequent testing,” said lead inventor Dr Danny Jian Hang Tng, medical officer at Singapore General Hospital’s department of infectious diseases.

“This may enable us to manage COVID-19 more effectively not only at the point of care, but also in settings such as airports, conventions and even at home,” Tng added.

The True Accuracy Of Tests For Covid

Unfortunately, its not clear exactly how accurate any of these tests are. There are several reasons for this:

  • We dont have precise measures of accuracy for these tests just some commonly quoted figures for false negatives or false positives, such as those reported above. False negative tests provide false reassurance, and could lead to delayed treatment and relaxed restrictions despite being contagious. False positives, which are much less likely, can cause unwarranted anxiety and require people to quarantine unnecessarily.
  • How carefully a specimen is collected and stored may affect accuracy.
  • Because these tests are available by EUA, the usual rigorous testing and vetting has not yet happened, and accuracy results have not been widely published.
  • A large and growing number of laboratories and companies offer these tests, so accuracy may vary.
  • All of these tests are new because the virus is new. Without a long track record, assessments of accuracy can only be approximate.
  • We dont have a definitive “gold standard” test with which to compare them.

Saliva On College Campuses

Used in the proper context, saliva may still be useful in tracking down even asymptomatic infections. College campuses across the US, for example, are using saliva-based tests to screen students and staff.

Campus is a high-risk environment for transmission of the virus, so even if you dont have the traditional symptoms, youre still considered at risk, Banister says. Because of that . . . we wanted to make sure that college students who may not suffer any ill effects are also not contributing to our city-wide number of cases by spreading it.

The University of South Carolina, located in Columbia, recently began testing as many as 1,200 student volunteers a day using Banisters saliva test, hoping to catch invisible infections in its students. Rather than testing each person once, the university has opened the testing up to students on a repeat basis, with results arriving within 24 hours. Through this mass testing, the university has identified clusters in campus fraternities and sororities, and as of today has 33 active cases among students.

At the end of two weeks, the two samples diverged, with swabs continuing to detect virus for several more days. Banister attributes this finding not to a higher sensitivity of the swab test, but to the mechanics of the human body: saliva turns over much more quickly in the mouth, while the lungs and nasal cavity can hold the virus for longer, leading to positive results even when a person may no longer be infectious.

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Key Findings Of The Study

In the first phase, 28.3 per cent of NPS, saliva, or both samples were positive for SARS-CoV-2. When compared to NPS, the detection rate in saliva was lower . In Phase II, 50.2 per cent of saliva, NPS, or both samples were positive for SARS-CoV-2. When compared to NPS samples, the detection rate in saliva was greater . The detection rate for the 85 saliva samples tested with both procedures was 100% for samples tested with SalivaAll and 36.7 per cent for those tested with procedure U.

Should People Change Their Behavior

How to conduct an at

Even without a clear explanation for whats going on with Omicron testing, some countries have responded to recent studies by recommending changes in the way people use rapid antigen tests.

Israels health ministry, for example, has advised people to swab both the nose and throat, Reuters reports this week. Several researchers in the US have discussed the same as a way to potentially boost a tests chance of picking up enough virus to detect.

Researchers who spoke to The Scientist say that theres a lack of evidence that this practice is beneficial. I think the headlines have already outpaced what we know, as far as the throat goes, Gronvall says, adding that using this approach on tests that are designed to work only with nasal swabs is clearly not an FDA-approved way to go. While it would be surprising if didnt work with a combined throat-and-nasal swab, she says, more studies will be needed to show if it makes a difference to test performance.

Some countries have responded to recent studies by recommending changes in the way people use rapid antigen tests.

The FDA itself has advised against the practice, stating in a last week: The home antigen tests available today are only authorized using nasal swabs. We dont have any data yet suggesting throat swabs are an accurate or appropriate method for at-home tests.

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Experts Question Claimed Accuracy Of Covid

Two members of the Royal Statistical Society say UK governments figures rely on spiked lab tests and not real world tests

Saliva tests for Covid-19, which are being introduced for NHS workers as part of the governments mass testing programme, pick up only 13% of people with low levels of the virus and not 91%, as the official assessment has claimed, according to experts.

Two members of the Royal Statistical Societys working group looking at the accuracy of Covid tests have questioned the results and the way they have been evaluated.

Prof Jon Deeks from Birmingham University and Prof Sheila Bird, formerly of the MRC Biostatistics Unit at Cambridge University, say the tests perform poorly where people have low levels of the virus, which is often the case in people without symptoms.

They say the discrepancy in the figures is because the evaluation used spiked samples saliva to which the virus has been added in the lab. Those manufactured samples were picked up efficiently by the test, but real world samples from people with asymptomatic Covid were not.

The OptiGene RT-Lamp test, which can be used with saliva samples or nose swabs, was intended to be part of the Liverpool mass testing programme, routinely offered to asymptomatic NHS workers. People in the community have been given lateral flow tests, which involve nose and throat swabs. Both tests have the advantage of speed, with results within half an hour.

How does the Pfizer/BioNTech Covid-19 vaccine work?

South African Study Suggests Nasal Swabs Aren’t The Best Way

byJohn Gever, Contributing Writer, MedPage Today December 27, 2021

If confirmed in follow-up research and if the diagnostics industry can pivot quickly enough, findings from a South African study could make COVID-19 testing a lot easier for patients and healthcare workers, as the SARS-CoV-2 Omicron variant becomes the dominant source of infection.

In a manuscript posted to the medRxiv preprint server on Friday, researchers from the University of Cape Town reported that saliva samples yielded more accurate results in PCR analyses when Omicron was involved compared with those collected via nasal swabs.

When patients carried the Delta variant, on the other hand, nasal swabs were more accurate, according to the group, led by Diana Hardie, MBChB, MMedPath, who also heads the diagnostic virology laboratory at Groote Schuur Hospital.

The findings came from an analysis of 382 patients tested at Groote Schuur from August through this month, with viral whole-genome sequencing performed on isolates from those with positive results. Just over 300 were tested prior to Omicron’s emergence, with 31 testing positive for the Delta variant. Another 74 arrived at the hospital after Omicron became common, of whom 36 were positive for that variant.

All patients had both saliva and mid-turbinate nasal samples taken for RT-PCR analysis. The “gold standard” for positivity in the study was detection of SARS-CoV-2 RNA with either swab.

Disclosures

Primary Source

medRxiv

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Molecular Scissors And Heated Chambers

To identify targets for their test, the researchers performed a bioinformatic analysis of a specific region of the SARS-CoV-2 genome responsible for the viruss replication.

They found a region of a gene known as the nucleoprotein was common to different virus variants and did not share features with other coronaviruses.

They then used CRISPR-based molecular scissors, an enzyme known as Cas12a, to bind to and cut this area of the nucleoprotein gene to produce a fluorescent signal that can serve as a test result. They also created additional assays to test for Alpha, Beta, and Gamma variants of SARS-CoV-2.

While clinical samples rarely use saliva, easier to collect without clinical expertise, minimizing the risks of improper sample collection in at-home tests.

One of the reasons why saliva is used less often is because it needs processing before analysis to avoid false-positive signals. To circumvent this issue, the researchers added chemicals called DTT and EFTA to saliva samples and then heated them to 203°F for 3 minutes. This destroyed the enzymes in saliva that are responsible for creating false-positive signals.

They then poured the resulting nucleic acids onto an absorbent cellulose membrane and placed it in a low-heat 98.6°F reaction area. Within 55 minutes, they could observe a visual fluorescent readout indicating whether SARS-CoV-2 was present in the sample.

Testing Recommendations For Fully Vaccinated Individuals

New Saliva-Based COVID Antibody Test Is Highly Accurate, Johns Hopkins Study Says
  • Fully vaccinated is defined as 14 days after your final dose.
  • If you are identified as a close contact of someone who tests positive for COVID-19 and you are fully vaccinated, you should test 3-5 days after exposure if you do not experience symptoms.
  • If you do experience symptoms, you should quarantine and test immediately. Recent data shows the Delta variant viral load may continue to be high for several days after onset of symptoms. By quarantining and testing immediately, you help protect those around you and prevent many more potential infections from occurring.
  • You should also take an on-campus COVID-19 test if you:
  • Experience COVID-19-like symptoms such as: fever, chills, cough, shortness of breath, fatigue, nausea or vomiting, headache, new loss of taste or smell, sore throat, congestion or runny nose, muscle or body aches or diarrhea
  • Return from travel
  • If you are contacted by the university because you are in an area with significant increases in positive cases , everyone in that location will be required to test every other day for a period of time until cases improve.
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    The University Of Illinois Saliva Test

    Our on-campus testing sites administer a saliva-based test, a process developed by the COVID-19 SHIELD: Target, Test, Tell team. Unlike conventional nasal testing, saliva samples are collected non-invasively, without healthcare workers and with minimal use of PPE.

    The University of Illinois System received emergency use authorization from the U.S. Food and Drug Administration for the innovative saliva-based COVID-19 test.

    The lab processing the samples is certified under the federal Clinical Laboratory Improvement Amendments of 1988 to perform high complexity testing.

    Collecting Samples Of Saliva Or Swabbing The Inside Of The Mouth Could Help Identify People Who Are Infected With The Virus Days Earlier Than Nasal Swabs Do Some Research Suggests

    Over the past two years, diagnosing a coronavirus infection has often required probing the nose. Health care workers have inserted slender swabs deep into the recesses of Americans nasal passages, while at-home test kits have asked us to master the shallow double-nostril twirl.

    The traditional approach to diagnosing respiratory infections has been to go after the nose, said Dr Donald Milton, an expert on respiratory viruses at the University of Maryland.

    The virus shows up first in your mouth and throat, Milton said. That means that the approach were taking to testing has problems.

    Collecting samples of saliva, or swabbing the inside of the mouth, could help identify people who are infected with the virus days earlier than nasal swabs do, some research suggests.

    The science is still evolving, and the data paint a complex picture, suggesting that saliva-based tests have limitations of their own. Many labs are not currently set up to process saliva, nor are the at-home antigen tests available in the United States authorised for it.

    But even saliva sceptics acknowledge that oral specimens have some unique advantages. And with omicron on the march, some experts say that testing companies, labs and federal officials should be working more urgently to determine the best sample sites and types for the virus.

    The case for saliva

    Some laboratory professionals were sceptical that saliva testing would be a reliable way to detect infection.

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    Saliva Covid Tests: What Educators Need To Know

    ByErik Ofgangpublished 27 September 21

    Saliva COVID tests are inexpensive, fast, and less cumbersome than nasal swabs, say spit test enthusiasts.

    At the start of the pandemic, University of Illinois researchers developed a saliva-based COVID test.

    They realized early on that if we were going to reopen the university, we would need a test that could be done quickly, cheaply, and that people wouldn’t mind repeating over and over and over again, says Rebecca Lee Smith, an epidemiologist at the University of Illinois, who designed the studies that earned the Illinois test its emergency use authorization. It’s easier if you’re going to do it frequently, to do drooling rather than having something stuck up your nose.

    Saliva COVID tests, aka spit tests, are ideal tests for schools looking to conduct regular monitoring of students or other populations and launch Test to Stay policies, say public health experts who have studied the tests. Saliva tests can also serve as a complement to other tests such as rapid antigen ones.

    The top saliva COVID tests are relatively inexpensive, highly accurate, and can be fast as results are generally available within a matter of hours. These tests are also easy to administer, especially for kids, and are already in use at many schools and universities across the country.

    For Coronavirus Testing The Nose May Not Always Be Best

    How to conduct an at

    As Omicron spreads, some experts are calling for a switch to saliva-based tests, which may detect infections days earlier than nasal swabs do.

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    By Emily Anthes

    Over the past two years, diagnosing a coronavirus infection has often required probing the nose. Health care workers have inserted slender swabs deep into the recesses of Americans nasal passages, while at-home test kits have asked us to master the shallow double-nostril twirl.

    The traditional approach to diagnosing respiratory infections has been to go after the nose, said Dr. Donald Milton, an expert on respiratory viruses at the University of Maryland.

    But the rapid spread of the Omicron variant, and questions about the sensitivity of at-home tests, have rekindled a debate over whether the best way to detect the virus is to sample a different site: the mouth.

    The virus shows up first in your mouth and throat, Dr. Milton said. That means that the approach were taking to testing has problems.

    Collecting samples of saliva, or swabbing the inside of the mouth, could help identify people who are infected with the virus days earlier than nasal swabs do, some research suggests.

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    Findings Build On Collaborative Effort To Design 3d

    BOSTONAs the highly transmissible Delta variant of the virus that causes COVID-19 surges in the United States and around the world, rapid and accessible COVID-19 testing and increased vaccination are key to managing the virus spread. Nasopharyngeal swabs long, medical-grade probes used to collect samples from deep in patients noses and throats are the gold standard for COVID-19 diagnostic testing. However, memory of shortages of both the specialized NP swabs during the early days of the pandemic as well as pressure on the trained medical personnel needed to perform the tests point to the need for simpler COVID-19 testing.

    In a real-world trial, a team of clinician-researchers at Beth Israel Deaconess Medical Center have demonstrated that tests of self-collected saliva provided comparable results to tests performed by trained healthcare professionals using NP swabs. The researchers concluded that saliva tests detect 93 percent of COVID-19 infections in an outpatient setting. The findings, which are published in the journal Microbiology Spectrum, could help alleviate the testing bottlenecks that have constrained COVID-19 testing since early in the pandemic.

    We have demonstrated that for practical purposes, saliva is comparable to NP swabs for COVID-19 testing in outpatient settings, said Arnaout, who is also associate professor of pathology at Harvard Medical School.

    Collection Kits Vs Self

    Self-collection at-home kits are usually molecular PCR tests that are more accurate than rapid antigen at-home tests.

    Generally, molecular PCR COVID-19 tests are more accurate than rapid antigen tests, whether performed in a hospital or at home.

    One of the most important factors in getting an accurate result from at-home COVID-19 tests is the amount of virus in your body. If a lot of virus has built up in your body, you are more likely to accurately test positive.

    The amount of virus in the body is determined by how long its been since you contracted the virus and whether you have COVID-19 symptoms. If you contracted the virus within one day, you will not have as much virus in your body compared to if you contracted the virus several days ago. Additionally, if a lot of virus has built up in your body, you are more likely to have symptoms.

    If you test when you don’t have symptoms, there’s a greater chance of a false-negative result. A false negative is when the test indicates you do not have the disease, but you actually do. In general, when a person is infected with COVID-19, molecular PCR tests can accurately detect the virus 99% of the time. This is called the sensitivity of the test. The sensitivity of rapid antigen tests is lower, at 90%.

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