I just saw the statement from Kayleigh, the press secretary said about repeatedly testing negative and now testing positive and some folks seem confused. So I guess it’s time to explain (again) how testing works.

We do not yet know what the infectious dose (how many virus particles you need to become infected) is so I’m going to use hypothetical numbers for the sake of this explanation. Buckle up.

The most common test people are getting is a PCR test which essentially detects virus genetic materiel (RNA in this case) up to a certain threshold. The test the White House has been using is the rapid test which detects virus proteins. Both meant to be surrogate for infection

So if the infectious dose of SARS-CoV2 was say 10. That means you need 10 virus particles to become infected. Let’s say PCR requires a minimum of 1k particles to be detected and antigen test requires 1.5k (the numbers are arbitrary please don’t tweet me).

On day 0 when I contract SARS-CoV2 there are 10 particles so I would not test positive. Let’s say for every 1 particle it produce 5 more particles every 24 hours that means I wouldn’t be at detectable levels until day 3 for PCR and day 5 for antigen test

Let’s also say that I start shedding at 600 virus particles. That means at some point on day 2 I start shedding virus and being able to infect other people.

I’m asymptomatic until I have 4K particles (reminder, made up numbers). So I’m walking around asymptotic, shedding virus and not wearing a mask because I tested negative day 1 and day 2. This is why a negative test is only good for one day.

Why we need to be testing way more and why people should be wearing masks.

This scenario doesn’t even take into account that antigen test can be inaccurate and isn’t meant for use in asymptomatic people at this point in time.

In real life we know the incubation period can be 2-12 days. So until you get to the last day with a negative test you can still be infected. This quarantine and wear a mask if you have been exposed. K thanks bye

This is why Biden is not in the clear yet and no one from the Rose Garden shindig either.

Or or or or anyone in contact with Trump before he started to quarantine.

Or or or or or or or or anyone who has come in contact with the Rose Garden Shindig attendees and staff (has anyone checked on the staff ?!) we see how and why this can get so messy so quickly and why it’s just easier to wear a mask right? And like diligently test ppl?

Gonna take this opportunity to say: GET YOUR FLU SHOT! K thanks bye.