Thread by @katherineefoley

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
qz.com/1954762/can-yo…

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. qz.com/1082724/the-hu…)

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. stm.sciencemag.org/content/early/…

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! qz.com/1954762/can-yo…