Issue 103

Immunology in your mucosal membranes, falling life expectancy, and a glob of amino acids.

Hello friend! Welcome to Scrap Facts.

I'm a reporter covering health and science with insatiable curiosity. I love everything I learn, not all of which gets its own story. Each issue, I'll bring you some of my favorite facts that I picked up on the job or while out living life.

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Mucosal immunology is “ridiculously complicated.”

Found while reporting: Can you spread Covid-19 if you get the vaccine?

Our protective immune system is not universal across our bodies. The immune cells that patrol our innards—places like our blood vessels, muscle tissue, and organs, which have no contact with the outside world—are aggressive: They see an intruder and hit hard and fast by producing antibodies called immunoglobulin G (IgG). And for good reason! Infections in those areas are brutally hard to treat and especially dangerous.

IgG antibodies are the kind we happen to make when getting vaccines that are jabs in our upper arms…like, say Covid-19 vaccines. Our arm muscles end up doing the majority of the legwork (heh) of making an immune response against Covid-19. And they work well at preventing Covid-19 cases, based on the data vaccine manufacturers have presented to regulatory authorities across the globe.

Interestingly, though, IgG antibodies aren’t the ones that would necessarily stop Covid-19 transmission. SARS-CoV-2, the virus that causes Covid-19, spreads through the parts of our bodies that interact with the outside world: our respiratory pathways, which include our noses and mouths. These areas are called mucosal surfaces, and they basically line everywhere on our bodies that aren’t covered with skin. (Skin, by the way, is first and foremost a part of our immune systems we don’t consider—it’s an ideal physical barrier to the outside world! And the biggest organ you’ve got. In addition to being the most aesthetically pleasing.)

The immune cells that patrol these pathways are a lot chiller than than the immune cells in our blood streams. They produce immunoglobulin A (IgA) antibodies, and they only attack things they know for sure can hurt us. And again, for good reason: If they set off an immune response every time a foreign object entered our systems, we’d be sick all the time. We’re never not exposed to foreign entities. How these immune cells make their selection is a field called mucosal immunology, and it has entire journals dedicated to it because it’s so complex and opaque (for now).

So IgA antibodies are the ones that can stop SARS-CoV-2 on our mucosal surfaces—and vaccines don’t necessarily generate those kinds of antibodies. Which sounds bad! But, we know that vaccines still prevent a lot of Covid-19 cases, which means at the very least that the virus isn’t getting a chance to replicate a lot. Less replication means less of a chance to spread it to others. How much so? Unclear—but promising! We’ll know more the more people get vaccinated by looking at how case counts decrease.

If you’ve been lucky enough to get vaccinated, congrats!! You’re at a much lower risk of getting sick with Covid-19, and spreading it to others. But just in case, you should still be wearing a mask. It won’t be forever.

US life expectancy is about to take its biggest downturn in years—particularly among marginalized groups.

Found while reporting: What Covid-19 is doing to life expectancies for Black and Latino Americans.

This chart should speak for itself.

Black and Latino populations have been hit exceptionally hard by the Covid-19 pandemic—and it’ll likely have a long-term effect on their life expectancies from birth.

There is still time to reverse, or even flatline these trends—but it’ll take continued protective measures and an effective vaccine distributions among these populations. This is going to be made even harder by the distrust many people in these groups feel after the present and historical neglected or abused by the US medical system. Effectively reaching these groups will require a lot work, which at the moment seems to be shouldered by unpaid or underpaid community leaders and physicians of color.

PS. The US hasn’t been great at collecting its non-White populations, which is why the Hispanic life expectancies on the chart above don’t start until 2006. Hispanic here also means “Hispanic or Latino”—there’s a slight difference in the two words, which you can read about here.

The Covid-19 spike protein isn’t a “spike” so much as its a massive amino acid glob.

Found while reporting: Will the Covid-19 vaccine work on the new variants?

I’ve written in the past about how the SARS-CoV-2 spike protein works like a key to the ACE2 receptor in our cells. It’s a good analogy! But perhaps misleading in the kind of shape we’re working with.

The spike proteins on the SARS-CoV-2 virus actually line the sphere. They’re a mix of some ~1,300 amino acids (think LEGO bricks for proteins), with some sugar molecules on there. They’re also not stagnant, and can shape-shift to be either stickier on the surface of our cells, or sneakier getting into our cells into our cells. Because the spike protein has such an integral role in infection, all the vaccines available so far target it.

A lot of the mutations you’ve probably heard about with SARS-CoV-2 represent slight changes to the spike protein. Variant B.1.1.7, for example, has swapped out a dozen or so amino acids on the protein for another on spike proteins, which happen to provide an extra opportunity for the virus to infect our own cells. This makes it about 50% more infectious.

While scientists are studying whether these mutations can help the virus evade antibodies from a vaccine (an idea which sounds terrifying) it’s important to remember just how big spike proteins are: The fact that they’re made up of over 1,000 amino acids means that swapping a few out here and there won’t matter too much in the long run.

Even some of the vaccine trails that have shown less efficacy against some mutations, some priming to our immune system by a vaccine is better than none. Our immune system learns over time, and adapts to new circumstances (much like we do, dear reader). If the immune response a vaccine generates aren’t a perfect defense to a new spike protein, it’ll change.

That change in response may take some time—which is why it’s still as important as ever to try not to get sick, as much as possible. But all hope is not yet lost.

Other work you may have missed:

Why has vaccine rollout has taken so long? For Aspen Ideas, I spoke with virologist and vaccinologist Florian Krammer from the Icahn School of Medicine to answer some of these questions.

Pet food suffers the same marketing gimmicks as people food. Without the invention of pet food, we’d never have pets! But we now also have a highly competitive market, desperate to pull in health-conscious pet owners.

PCR testing won’t help reopen your workplace. Look to antigen testing instead—it’s cheaper and produces faster results, even if it’s not your lab gold-standard.

Some workplaces are paying employees to get vaccinated. Dollar General was one of the first to announce such an incentive.

Biden’s pick to head Operation Warp Speed is an anomaly among FDA commissioners. David Kessler one of the few to have minimal ties to Big Pharma. This pick goes in line with Biden’s generally scientific approach to stopping the pandemic.

Don’t stress if you get your second Covid-19 shot later than you meant to. More time for your immune system to learn is generally a good thing.

Drug companies are teaming up with competitors to mass-manufacture vaccines. It’s a first in Big Pharma’s history.

And finally, everything we know about the only one-jab vaccine in late-stage clinical trials.

That’s all for now—stay curious, friend ❤️

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Top image by Rachel Couch; headshot by Matt Anzur.