Spouse got his first dose of Moderna's vaccine today! His arm's sore and he's a bit tired and not feeling 100%, but that's not a worry at all — it's evidence that his immune system is already hard at work. 1/
Protection takes energy and effort and I'm proud to say his body is rising to the challenge.
He got the vaccine this morning, so right now we can expect that his cells are starting to churn out some spike protein. Spike is not infectious and it can't cause Covid. 2/
But those proteins will teach a cadre of immune cells to recognize one of the coronavirus's most salient features. That way, if the real virus comes around, his body will recognize it and marshal forces to keep him from getting sick.
It's pretty incredible stuff. 3/
Spouse is headed back for dose 2 in 4 weeks so he can get full protection. This vaccine will not be changing either of our practices around masking or distancing.
But because he's feeling a bit sluggish, we're administering cats and repeating as necessary. 4/4
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It's 2021! Time for a crash course in four terms that I often see mixed up when people talk about testing: sensitivity, specificity, positive predictive value, negative predictive value.
These terms help us talk about how accurate a test is, but from different viewpoints. 1/
Viewpoint 1 is about the status of the person taking the test. Are they infected, or not infected? How good is the test at identifying these people? That's sensitivity/specificity. 2/
A test that is very *sensitive* will be very good at accurately identifying people who are infected.
A test that is very *specific* will be very good at accurately ruling out infection in people who are not infected. 3/
Tests don't stop when you get your result. Think about the circumstances under which you took that test — they could really influence how you interpret what that test tells you. 1/
For starters: Positive and negative can be useful words, but we should be careful not to overinterpret them. Think instead about "detected" and "not detected." We're describing what a test has found — not a permanent identifier that says anything about who you are as a person. 2/
A "negative" result could be outdated within hours, either because the virus has built up to detectable levels, or because you were exposed anew.
"Positive" in the context of disease can also sound incriminating. 3/
The world has never asked this much of clin micro and public health lab workers.
Tests are not just pushed buttons and sloshing liquids. They make fingers ache. They make eyes water. They require sprinting back and forth, and perfect pipetting precision. 2/
We do not often look inside these labs. And for decades, that's been okay. “We’re accustomed to holding things up in the background," one scientist told me. "We enjoy doing it because we know we’re helping people.” 3/
In the leadup to the holidays, maybe we can start talking about our coronavirus tests in a slightly different way.
If you do not test positive for the coronavirus, consider that is more about the virus being "not detected," rather than you being "negative" for the virus. 1/
Because maybe the virus is there — but it's not yet present at high enough levels to be found on a test. You could still be infected. You could still be contagious. You could test again tomorrow and be positive; you could test again in five hours and be positive. 2/
Or perhaps you're not infected yet. A test is a snapshot in time; it says nothing about your status in the future. Every trip to the grocery store, even masked, could be an exposure. And a test today won't catch tomorrow's infection. Tests are also imperfect. 3/
Researchers working with harmless, noninfectious genetic material from the virus (in the form of DNA) were testing positive, over and over again.
They weren't shoving their science up their noses. They were being careful, and doing great work.
The DNA clung to them anyway. 2/
If that DNA happened to overlap with the target of a coronavirus test, that quickly spelled trouble for some. The test picked up that "contaminating" DNA, and thought hey, this is exactly what I was looking for. Positive. 3/
Rapid tests are already being used to screen people without symptoms for the coronavirus — even though they're not cleared for this purpose, and the data in asymptomatics is sparse.
Some of that data is emerging. It might not be what some hoped. 1/
Is there still a role for rapid tests? Absolutely. More data will be needed to figure out where they fit in best. But for now, it's crucial for people to understand that not all coronavirus test negatives are created equal. 2/
Testing negative on less sensitive tests, for example, might not mean you're virus-free.
Could it mean you're not infectious? Maybe. That's really, really hard to test.
It's very likely to be the case that people will less virus in their bodies are less infectious. 3/