January 20, 2021

Dr. Stuart Weiss: COVID-19 Update Tuesday 24-November-2020

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By Dr. Stuart Weiss, Intelligent Crowd Solutions

Rapid Test Center of New York
Dr. Stuart Weiss, FACEP, FAAP, CBCP

Nov 24, 2020

CoViD-19 News and Information you can trust.Welcome new readers from the Rapid Test Center.

Topics: Testing

Testing, testing, one, two three…

Recently, I’ve gotten many questions about testing so let’s talk about CoViD testing again since it’s been a little while.

First let’s remember basic terms. CoViD-19 stands for Corona Virus Disease. If you put the letters together it forms the word “CoViD” and it started in 2019 so its CoViD-19. CoViD-19 is caused by the SARS-CoV-2 virus (this stands for Severe Acute Respiratory Syndrome – Corona Virus – 2). This family of viruses are called corona viruses because they have spike proteins that stick out and form a covering that looks like a crown and the latin word for crown is corona. So now you can look smart at Thanksgiving dinner when CoVid comes up in conversation.

There are two types of tests out there. One type looks for antibodies and one looks for actual virus. As you may recall, when we have an infection, our body creates antibodies that stick to invading viruses or bacteria and help other cells in our immune system attack the disease invaders. So measuring antibodies will tell us if you HAD an infection but it doesn’t really help tell us if you have an infection right now. This is because it takes a week or so for our body to create specific antibodies in response to an infection. So you can have SARS-CoV-2 virus growing in your body and be antibody negative. We also don’t know how much antibody you need to have in your body to be protected so antibodies are not so helpful.

What we can do is look for actual virus. The SARS-CoV-2 virus is a respiratory virus mostly and likes to grow in the lungs and respiratory tract. As you may recall, it gets into our cells using a common receptor in our lungs and respiratory tract called the ACE-2 receptor. The virus binds to that receptor and fools our cells into allowing the virus inside. Its like a criminal ringing your doorbell and telling you they are the UPS driver and you open the door and let them in. Once inside, they take over and create havoc. Once the virus is inside your cells, it takes over and forces your cells to make millions of copies of itself. Viruses are very good at doing this and that is how they survive. Tricky little devils.

So back to testing. When we test for virus, there are essentially 5 levels of tests. All of these tests are approved by the Food and Drug Agency (FDA) under an Emergency Use Authorization or EUA. This fast approval process allows tests to come to market quickly by skipping most of the rigorous testing that usually goes into medical devices and tests. So, there is little actual data to look at when evaluating tests.
The gold standard which all other tests are measured against is the real time reverse transcriptase Polymerase Chain Reaction test or rrt-PCR test. These are the lab based tests that take 24 to 36 to longer hours to get the results. They are super sensitive and pick up even tiny bits of virus.
The test can not differentiate between living virus or dead virus which is a problem because some people can shed small amounts of dead virus for up to 90 days after recovering from CoViD. Some people think it may even be overly sensitive but that is another column. During the height of the early days of the pandemic, these rrt-PCR tests took up to 8 or 9 days to come back and that made them useless.

So, we needed faster tests. You sacrifice some accuracy for speed so these other tests are less accurate. The next level down are the rapid rt-PCR tests. These are the tests that we run at our testing center because I think they are a good balance between speed and accuracy. At the level of virus in our bodies where we are contagious, these tests correlate exactly to the rrt-PCR tests. They become less accurate at the very very low levels of virus which I’m not sure we care that much about. But they are a bit less accurate at these low levels. The tests we use are the Mesa Biotech Accula platform tests. These tests take 30 minutes per test.

The next level down are the rapid isothermal Nucleic Acid Amplification Tests (isothermic NAAT) like the Abbott ID NOW test. These are faster, only take 15 minutes per test, and are less accurate than the rt-PCR but only by a little bit. They have been studied in symptomatic patients but little data is available on asymptomatic patients. We used to run these in our center prior to the rapid rt-PCR tests and I thought they were acceptable. In our work with TV and Movie productions, they accept the Abbott ID Now tests.

The next level down are the rapid antigen tests. There are two currently approved in the US. They also take about 15 minutes and can achieve very high throughput. Their accuracy is lower than the Isothermic NAAT test, around 90% accurate. I am not a big fan of antigen tests because of their accuracy issues but many people find the data acceptable. There are some new antigen tests on the horizon that have great accuracy numbers and when they come out I’ll be excited. The great thing about antigen tests is that they require very little machinery to run.

The fifth level are called Lateral Flow Assays and are similar to home pregnancy tests. These tests are cheaper and designed for mass population screening. In these situations, since we are testing people a couple of times per week, having a really low sensitivity is okay because if we miss you on one day, we will pick you up on the next day. These do not work for single test scenarios like entrance into a stadium or back to work since the sensitivity is too low.

This past week, a really interesting test was approved by the FDA. Its a home test similar to rrt-PCR (actually rt-LAMP for you purests out there) and the accuracy is great. It will cost around $50 but won’t be out for months. Also, as I said above, some good advances in antigen technology are coming as well.

So that’s testing in a nutshell. People also ask me about false positive tests and false negative tests. Every medical test you have ever had has false positive results and false negative results. A false positive test is where you do not have CoViD but the test comes back positive. False negative, which is more common, is where you actually do have CoVid but the test is negative. This is where your physician can help you figure out if your results do not make sense. For the most part, if you have a positive test, you are most likely infected. There are some cases where people have a series of negative tests (like on movie sets where the actors are tested 3x per week) and then have one positive and have no symptoms at all. In that case, I sometimes will do 2 additional tests, one on each of the following two days and then determine that the one positive was a false positive. That only works for people in a regular testing regimen. This does not apply to people who test intermittently. On the other side, if you have symptoms and test negative, I might conclude that you had a false negative, which is much more common with rapid tests.

Finally, there is no protocol for testing out of isolation in most cases. If you have a positive test, you need to self isolate for ten days. If you have close contact with someone who tests positive, you need to quarantine for 14 days.

I hope that clears up some of the confusion about testing. I am happy to take questions on this and answer them in future columns.

Stay safe while you enjoy the Thanksgiving holiday.

Be well,

Dr. Stu Weiss
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Coronavirus update for November 24, 2020

World Wide Updates

UK will loosen Covid-19 restrictions for Christmas
Hong Kong tightens social distancing rules after infections spike from dance club cluster
Germany’s state leaders agree on a plan to limit Christmas and New Year’s celebrations
Pope Francis criticizes people who refuse to wear masks
Japan’s Covid-19 death toll surpasses 2,000
Christmas on Europe’s ski slopes looks unlikely
Sputnik V vaccine is 91.4% effective according to interim data, says Russia
Frenchman fined for breaking lockdown to “smash a guy’s face in”
China says it “took the lead” in inviting WHO experts to trace the virus
Malaysia’s biggest glove maker temporarily shuts more than dozen factories after Covid-19 outbreak
WHO scientists continue investigation into coronavirus origins and plan trip to China
Virus rates are still falling in Belgium, though more slowly than at the start of November
Italy to start distributing Covid-19 vaccine at the end of January, says PM
Spain’s King Felipe enters 10-day quarantine after contact tests Covid-19 positive
France expected to ease lockdown in three stages
Japan and China will restart business travel by end of November
Study finds a very small link between blood type O and lower risk for severe Covid-19 illness
Gulf countries surpass 1 million Covid-19 cases
South Korea reports nearly 350 new Covid-19 cases 
ICU admissions in Germany reach highest level during the pandemic
Qantas boss says passengers will need to be vaccinated for international flights
US reports more than 169,000 new Covid-19 cases
Belize prime minister tests positive for Covid-19
England cuts traveler quarantine period to five days
AstraZeneca’s Oxford coronavirus vaccine is 70% effective on average, data shows, with no safety concerns
Spain’s King Felipe VI under quarantine after coming into close contact with COVID case
Macron expected to set out plans to ease coronavirus restrictions
Italy reports highest daily death toll since March 28
French president says worst of virus second wave is over and lockdown to ease
Total Cases Worldwide: 60,016,000
Total Deaths Worldwide: 1,412,604
Total Recovered: 41,446,344

US Updates

FDA commissioner weighs in on whether employers and schools will require Covid-19 vaccinations
The Trump administration is considering shortening the recommended quarantine time for Covid-19
NFL players now must wear face coverings on the sideline during games
CDC director relying on Covid School Dashboard for advice on closing schools
Florida reports more than 8,000 new Covid-19 cases
YouTube penalizes One America News Network for spreading Covid-19 misinformation
Wisconsin reports more than 100 new Covid-19 deaths
New York governor reverses course on family Thanksgiving plans after backlash
Pennsylvania adds more than 6,000 Covid-19 cases
White House coronavirus task force calls for “significant behavior change of all Americans”
South Dakota tops 70,000 Covid-19 cases
Majority of Covid-19 spread being driven by asymptomatic people in household gatherings, CDC director says
Oklahoma surpasses 180,000 total Covid-19 cases
US could distribute Covid-19 vaccine “soon after” Dec. 10, HHS secretary says
Kentucky is “being overwhelmed” by Covid-19, governor says
Wyoming governor’s office closed due to Covid-19 case
The pandemic could be stopped if at least 70% of people wore face masks in public, new analysis finds
61% of Americans changed their Thanksgiving plans due to Covid-19 spikes, new poll finds
Arizona reports more than 4,500 new Covid-19 cases
51% of Americans say they are likely to take a first-generation Covid-19 vaccine, new poll finds
A Minnesota doctor cries as she describes “heartbreaking” experience of patients dying from Covid-19
Covid-19 vaccines will soon be tested in pregnant women and children, CDC director says
NYC’s health commissioner: “It is not too late to cancel your travel plans”
A negative Covid-19 test yesterday doesn’t mean you’re safe tomorrow, US surgeon general says
4 Vegas Golden Knights players test positive for Covid-19
California church hosts conservative activist in packed services defying public health orders
The US could have 20 million coronavirus cases by Inauguration Day, new model predicts
FDA asks committee critical to vaccine authorization to meet twice in December 
The US set another record for new Covid cases in children last week, AAP says
CDC may recommend shortening COVID quarantine to 7-10 days, report says
Lyft driver contracts COVID after racist incident with maskless passenger
Publix accused of failing to protect 70-year-old deli worker from COVID in new lawsuit
COVID-19 rules appear ignored at birthday party featuring Brooklyn political players
Los Angeles on brink of stay-at-home order as county sees ‘most dangerous moments’ since pandemic began
People are freaking out about the toilet paper shortage as COVID cases surge
CDC officials warn COVID vaccine aftereffects may be uncomfortable: ‘no walk in the park’
Total US cases: 12,916,159
Total US deaths: 265,573
Total Recovered: 7,605,049
Total Tested in US: 181,142,529
Total cases in TX: 1,202,395
Total deaths in TX: 21,365
Total cases in CA: 1,141,710
Total deaths in CA: 18,788
Total cases in FL: 953,300
Total deaths in FL: 18,164
Total cases in IL: 674,089
Total deaths in IL: 12,262
Total cases in NY: 644,335
Total deaths in NY: 34,297
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