Alright team, let's get to another pressing vaccine question a lot of you had asked recently: Can those who have gotten complete doses (2 shots) of #COVID19Vaccines transmit SARS-CoV-2 to others? Come with me on a lil mucosal immunology journey 1/x…
2/x The short answer is, we aren't sure. This is because the first thing clinical trials looked for is who was getting Covid-19—a symptomatic illness as a result of an infection with SARS-CoV-2. Which is good! That's the main job of a vaccine!
3/x To get Covid-19, your body has to be sufficiently overwhelmed with SARS-CoV-2. To get there, SARS-CoV-2 has to have copied itself a lot. We don't know if the vaccine prevents SARS-CoV-2 replication altogether, or just enough so the person doesn't get sick...
4/x ...If vaccines only prevent a person from getting sick, they could *maybe* still give the virus to others. Which is why it's important for folks who are vaccinated to wear masks + physically distance until we know more.
5/x PCR tests or antibody tests looking for SARS-CoV-2 antibodies other than the ones the vaccine prompts could answer these q. So could tracking community spread over time. If you want practicality, there's your answer! If you wanna get nerdy...come with me 😈
6/x #COVID19Vaccines are jabbed into our upper-arm muscle. Muscle cells are therefore leading the antibody production charge. They produce a type of antibodies called Immunoglobulin G (IgG) which make up the majority of your immune cells.
7/x IgG antibodies are EFFICIENT. They see a threat (like the spike protein of the SARS-CoV-2 virus) and they CRUSH IT like a pro-wrestling POWERSLAM. Which seems to work pretty well, based on clinical trial data. eg: Moderna + Pfizer-BioNTech vaccines stop ~9/10 Covid-19 cases.
8/x But IgG antibodies aren't usually the ones on our mucosal surfaces. Mucosal surfaces = anywhere where your insides meet the outside world (or anywhere w/out skin/nails). They include your nose/mouth/respiratory system, digestive tract, eyes, etc.
9/x Mucosal immunology is ridiculously complicated, Matthew Woodruff, an immunologist at @EmoryUniversity told me. This is bc you can't have a body slam immune response here; if you did, you'd be super sick. All the healthy microbes that co-exist with us would be under attack.
(9.5/x a lil' refresher on microbiomes. Man I miss writing about things like microbiomes.…)
10/x So instead of IgG antibodies, your mucosal surfaces have more iImmunoglobulin A (IgA) antibodies, which act like bouncers. They're selective about what they let in and what they attack. Eg: IgA in noses are chill with Staph bacteria bc they're normal there, but bad elsewhere
11/x As you may recall, SARS-CoV-2 spreads primarily through large and small droplets from our noses and mouths...which are mucosal surfaces! So when we think about spread, we're really asking about IgA antibodies against SARS-CoV-2.
12/x We don't know if vaccines generate a ton of IgA antibodies; seems like they make IgG antibodies. But people who have gotten sick+recovered from #Covid19 make a TON of IgA antibodies.…
13/x This doesn't mean that those w vaccine will DEF still spread virus; there are a ton of unknowns; the amount of virus you're exposed to, preexisting health conditions, how long antibodies/immunity memory lasts; all of those could play a role in spreading/not.
14/14 W/ the protection we saw in clinical trials, #CovidVaccines likely do prevent some degree of transmission, even with IgG v IgA antibodies. How much? We don't know. So get your vaccines + continue to take precautions for others, too!…

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More from @katherineefoley

11 Jan
Last week, the US Capitol had a huge problem which has since been overshadowed: @US_FDA flagged that the @Curative #COVID19 PCR tests it had been to screen entrants had more false negatives than expected. Here's what offices can learn to reopen safely: 1/x…
2/x The backstory: @Curative's #COVID19 PCR tests work like many others; they detect SARS-CoV-2 genetic material in quick swab. It returns results in 12 hours—which is fast for PCR! @US_FDA granted Curative an EUA in April; it also provides tests for big cities across the US.
3/x @US_FDA's warning last Mon. says tests have higher rate of false negatives, meaning someone could be told they don't have #COVID19 but they actually do. The risks are 1) that person misses out on treatment and 2) that person spreads the virus to others…
Read 13 tweets
4 Dec 20
As you've probably heard, we're getting close to having #CovidVaccines authorized in western countries (and they have been in the UK). It's tantalizing to think that life will be "normal" again soon, but there's a lot of factors to consider—a thread 1/x…
2/x For simplicity's sake, let's assume "normal" means people have been vaccinated to the point of herd immunity, everything is open, travel is fine (but expensive, like the good ol' days).
3/x Okay: Herd immunity means that enough people are sufficiently immune to an infection that it can't be transmitted to others. How many vaccinated people will that take? Well, it depends on two factors:
Read 12 tweets
19 Nov 20
The race to be the first to get a a #COVID19vaccine available is getting spicy: @pfizer / @BioNTech_Group, @moderna_tx, and @AstraZeneca are all close to releasing partial/full phase 3 trial data. But being 1st isn't the only way to win: A thread: 1/x
One excited thing buried in @pfizer's announcement yesterday was that it seemed like their candidate had 94% efficacy in adults over 65. 41% - 45% of their trial participants were 56-85 yo 2/x…
3/x This is huge*: The changes in older adult immune systems mean that generally, vaccines don't work as well in these populations.…

*If true beyond the press release!! We want data!
Read 11 tweets
10 Nov 20
One thing I don't see anyone talking about in the @pfizer #CovidVaccine discussion is the difference between efficacy and effectiveness. It's a small nuance, but it matters when we're talking about how to end the pandemic. A short thread: 1/x
2/x We got the news* yesterday that Pfizer's vaccine candidate seemed "90% effective." If we're going by the @CDCgov's definition, the company really meant "efficacy."

*It's from a press release. We want independent, peer-reviewed, published data before we make any conclusions
3/x "Efficacy" means a vaccine seemed to work at preventing illness in a randomized controlled trial. These trials are the gold-standard of scientific data, but they're also not reflective of the real world.…
Read 8 tweets
8 Nov 20
Folks, a lot of you are hearing about Wilmington, Delaware. As someone who essentially grew up in the biggest city in Delaware (pop: 71k) here’s what you’ve been missing every time you merely drove by it going up and down the east coast instead:
1) The Wilmington Blue Rocks, our minor league baseball team. Our mascots are, I kid you not, a stalk of celery and a blue moose named Rocky Bullwinkle (to avoid copyright infringement with the show “Rocky & Bullwinkle”) Image
2) Bellevue, Brandywine, Rock Creek, and White Clay creek state parks, where I spent my Saturday mornings running cross country races. These courses featured some of Delaware’s only hills (the state is a pancake). We have only 1 national park in the whole state (thanks, obama!)
Read 10 tweets
29 Oct 20
💩 Back in May, I heard about scientists trying to use wastewater as an early #covid19 warning signal. As I dug into that idea, I learned about their much larger ambition: giving one of the oldest public health tools a major glow-up.
A ~crappy~ thread: 1/x…
2/x We've got a love/hate relationship with poop. On the one hand, VERY BAD bc it transmits a lot of diseases; hence why we built sewers to keep it out of our drinking water. But on the other, a complete record of everything we've eaten, drank, or otherwise been exposed to...
3/x In the past, wastewater #Epidemiology has shown where there were pockets of polio outbreak or opioid usage—even before cases or overdoses popped up. Turns out, it looks like we can do the same thing with #COVID—it's RNA shows up in poop days before cases do.
Read 14 tweets

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