Bart writes:

Hi Twiv: 

I listen to TWIV every week. I thought I perfectly understood issues related to sensitivity/specificity of the PCR tests for detecting infection. However, until we had to get tested ourselves, I realized I am terribly confused after all. …and the more I read the more confused I am.

I’m reading various articles suggesting that even 4-5 days after infection (note not symptom onset – but INFECTION), PCR tests still have notoriously poor sensitivity (67% false negative 4 days after infection in one study). 

I’m terribly confused. I understood that the onset of symptoms, on average, occurred for the bulk of patients around that time, and that the viral load was at its peak just before and just after infection. 

PCR is incredibly sensitive if virus is present. So 4 or 5 days after infections, most patients should have enough detectable virus in the body – I thought  a PCR test should be able to pick this up and result in a +ve test. 

So why are PCR tests reported to have such high false negative rates?


Please help! or reference a TWIV episode if I missed this.

Thanks alot!

Loyal listener, 


Carolyn writes:

Dr. Griffin-

It would be great if you could comment on very promising results with the SSRI fluvoxamine- it seems to act through the sigma-1 receptor in the endoplasmic reticulum (unrelated to serotonin reuptake inhibition). It may impact cytokine secretion and/or impact virus replication directly.

A small outpatient placebo-controlled clinical trial was published in JAMA, and there are more data accumulating. See the links for more information. Steve Kirsch, who started the COVID early treatment fund (CETF), has funded some of the work.  

thank you!


(Johns Hopkins University)

Char writes:

Dear Dr. Griffin, 

If you keep missing your vitamin D doses, it is okay to take it weekly.  If you choose to use 4000 per day, then you could take 28,000 units just on Sunday.  Because it is an oil-soluble vitamin, If you take it with food that contains some oil or fat, it should all get absorbed. 

Yes, an RCT of vitamin D in covid would be great.  

But the paper you shared is compelling. (And Dr. Seheult shared a reference list on MedCram 12/10 too.)

Also, Vitamin D itself is very inexpensive. .  

So the high cost you are talking about must be the tests and the prescription vitamin D. 

I’m always looking forward to your weekly updates so that I can share the information.

I want YOU to stay healthy and continue full-steam ahead,

sending the very best wishes, 

Char Glenn, MD
Internist, mostly retired,  but still helping where I can. 

Portland,  Oregon

……………………Supplemental personal info………………………………

Experience from my primary care practice:

After watching a couple thousand people’s vitamin D levels  since 2000, with occasional tests til they were at the right level,  the only people who went too high on the vitamin D level were those who just put drops on their tongue (where one cannot feel all the drops) and one who took “10,000 units daily  for the past two years because my neighbor told me to use it.” Even though the blood levels were over 100, they did not have symptoms and their calcium was normal.  Thank goodness.

I did have about three people who needed to be followed by the endocrinologist for parathyroid conditions, not caused by taking vitamin D, but they needed to be more careful in following the dose.  Also of course people with granulomatous disease, sarcoid, kidney disease need to be careful about it. 

In a study at OHSU, the Oregon medical school, 40% of medical students were low on vitamin D.  A higher percentage of patients  in my practice were low if they were not taking vitamin D and were using sunscreen when outdoors (which prevents uv light from making the vitamin D in our skin).  In the Pacific Northwest, almost everyone is low in winter without the supplement.  Because deficiency was so universal here and the tests were expensive, the insurers got together and told the docs:  you don’t need to test the vitamin D level, just ask patients to take 2000 units.  The insurers stopped paying for the tests. 

Anecdotal, but consistent with the research I’ve, my patients generally needed 4000-5000 daily to get to a level of 35 to 50.  A very few do need 7000 or 10000 units daily.  Sometimes I do check the vitamin D1,25 to see if they are an excellent converter, which makes the D25 look low.   

Why do I care so much about this?   It has helped my patients with joint pain, low mood, reduction of frequent colds, and bone density especially if used with vitamin K to steer the calcium to the bones where it belongs.