Video and notes about testing, update on treatments and vaccines.
Here is a link to the video, which is on the Now Health YouTube channel.
During the video, I referenced the below information and references. You can follow along with the video, which is just under 40 minutes, or review the info and provided links, which will give you lots of great information.
Lab Testing- focus on testing for Coronavirus
PCR (polymerase chain reaction) testing
Nasopharyngeal swab – (swab way up your nose, like a flu test)
Goal is to get actual virus (viral RNA)
*In the lab, the sample is treated to preserve only RNA that is present. Enzymes are added to transcribe this RNA into DNA. This DNA then gets amplified in the PCR machine (makes a lot of copies).
*Each lab uses a set of coronavirus DNA fragments.
*If the sample has complementary viral fragments, they will bind together and “light up” with a fluorescent pattern. If a certain pattern lights up – the test is positive.
*Different companies use different regions of the coronavirus genome.
The CDC’s original test was a failure: it identified coronavirus correctly, but one of the chemicals was causing non-coronavirus particles to react as if positive – giving “false-positives”. This is when the FDA granted their Emergency Use Authorizations (test’s don’t have to go through a long proving process). As of March 30th, 20 of these EUA’s had been authorized.
The key to the PCR test is that you need an active virus to detect.
There are “point of care” pcr tests coming out now. These can give results in less than an hour. These are the tests they are talking about getting into villages right now and some of the local testing facilities will also get them. These will be helpful, but can only run one test at a time, whereas the more traditional PCR test equipment can run almost 100 samples at a time
Serology (Antibody) testing
These tests search the blood for antibodies to the virus. Which may be helpful in detecting who has already been exposed. It can take up to 8 days to develop antibodies, which is not really helpful, initially. Right now these are not widely available. I believe that there are some of these tests being used in Asia.
Common statistical terms discussed when talking about tests
Sensitivity: the ability of a test to correctly identify those with disease (true positive)
Specificity: the ability of a test to correctly identify those without the disease (true negative)
Estimates of current sensitivity for coronavirus testing: 70%
References:
Coronavirus testing is ramping up. Here are the new tests and how they work.
Sensitivity, specificity and understanding medical tests/understanding-medical-tests-sensitivity-specificity-and-positive-p
Every Vaccine and Treatment in Development for COVID-19, So Far
A Pediatrician’s Pandemic Immune Support Plan
I hope you find this information helpful. Please let us know of any questions.
Have a wonderful Easter weekend!
In health,
Dr Jill and staff
