Issue 98

The inefficient CO2 supply chain, scientists working from home, and Covid testing to see your friends

September 20, 2020

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 week, 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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The wonderfully weird supply chain of all the dry ice we’re going to need to ship Covid-19 vaccines.

Found while reporting: US carbon dioxide supply is a bottleneck for Covid-19 vaccine distribution.

The dry ice we have today depends in part on how much we were driving a few months ago.

Let me explain: You probably know carbon dioxide as the gas we breathe out, the gas plants breathe in, and one of the emissions from burning fossil fuels that has led to devastating wildfires across America’s west coast and hurricanes across the Southeast.

Carbon dioxide is also what we call dry ice—just in its solid form. Unlike actual ice, which melts into water, dry ice converts directly from its solid form to gas at ambient temperatures—a process called sublimation.

Dry ice is cold: on Earth’s surface, it’s about −78.5°C, or −109.3°F. Because it sublimates into CO2 gas—which is odorless, colorless, and for all intents and purposes here, inert—when it hits warmer temperatures, it’s a really nice tool to keep things like food and medicine frozen as they’re shipped across the country.

To get dry ice, you need pure forms of CO2—much purer than what’s in the air around us. Luckily, CO2 is a byproduct of making certain industrial chemicals. It’s also a byproduct of making biofuels, which are required by law to be a small component of the gas that fuels cars in the US (for now). Manufacturing plants can capture the CO2 they generate and sell it off to interested parties.

Unlike industrial chemicals, though, how much ethanol plants make largely depends on the demand for gas. When people stopped driving in March when the pandemic hit, demand for gas plummeted. Ethanol plants closed down, or decreased their production dramatically. As a result CO2 gas supplies went way down, leaving less and less available for the food and beverage industry, and less for dry ice for shipping medicines.

Fortunately, it seems like the shortage of CO2 is over—for now. But as we need to ship more vaccines across the country, availability of CO2 could become more of an issue.

Working from home isn’t working out well for top female scientists in the medical field.

Found while reporting: Covid-19 widened the gender gap among the world’s top scientists.

For a lot of scientists, working from home has meant pivoting from lab work or field work to writing up papers from data you collected ages ago. The good news: You can still work by publishing papers! Hooray! The bad news: Writing requires time, peace, and quiet—which may be harder to come by if you suddenly have to manage new caregiving needs for your family.

Unfortunately, publishing patterns indicate that the pandemic-induced caregiving burdens has fallen largely on women. Analyses of first names on academic papers has shown that female scientists have been publishing proportionately fewer papers than their male counterparts since January. Sadly, that trend even reaches some of the most senior scientists in the world: clinician scientists, who have a medical degree on top of another advanced degree in science.

The above chart shows that, according to medRxiv, a site that posts pre-prints of medical research papers, in January 2020, male authors published 23% more than female authors. By April, that figure was 55%. On bioRxiv, a site that posts pre-prints of biology papers, the gap was 46% more male authors than female authors, and 47% by April.

Of course, it’s impossible to know which researchers publishing medical papers are also parents. Conceivably, there could be another reason for this publishing gap.

Will this productivity slow down hurt women’s careers? It’s hard to say. But we do know publishing papers increases a person’s notoriety—a critical factor as they may be up for promotions.

At their best, the false negative rate for Covid-19 tests is around 20%.

Found while reporting: I took an at-home Covid-19 test. I can see my friends now, right?

A lot of people (myself included) have taken a Covid-19 test like these to rule out being an asymptomatic or pre-symptomatic carrier of SARS-CoV-2. Theoretically, if no one in a group has it, you can all safely interact with one another and disregard wearing a mask or maintaining distance. But the thing we all need to remember is that testing isn’t perfect.

A group from Johns Hopkins University published a review where they found that false negative rates go down the longer you wait to get tested after you’ve been exposed to the virus. On the first day, there’s a 100% chance your Covid-19 test will miss the virus; it hasn’t had enough time to replicate in you yet. On day four, there’s a 67% chance you’ll get a false negative. Day eight, when most people have had symptoms for a few days, there’s still about a 20% your test will still say you don’t have Covid-19, even when you do. After that, false negative rates go up again; it’s a U-shaped curve.

In other words, if you’re pretty sure you’ve been exposed to Covid-19 (meaning, you were close to someone who tested positive), and you get a false negative, you shouldn’t put a ton of faith into that result. Instead, you should isolate yourself for a full 14 days, and longer if you actually develop symptoms.

I write this not to freak you out or to discourage you from taking a test to go see your family or friends—social health is a vital part of mental health! But it is important that you and your loved ones make informed decisions.

You can still lower your risk of transmitting Covid-19 to others by staying outside, or wearing masks indoors, if possible. Self-isolating before and after a trip isn’t a bad idea, either! If you don’t want to do that, just consider who you’ve seen before and after, and who your group is comprised of—are there people at risk of developing severe cases?

There’s no right or wrong answer—it’s just important that everyone is well aware of the risks they’re taking on. That’s something you have to decide on a case by case basis with your loved ones.

Other work you may have missed:

Labor Day led to a small spike in Covid-19 cases in the US. I spoke to Arirang News in South Korea (at 1:30 am US time) about the pandemic in the US (min. 34 onward). It was quite humbling to speak on a news network where health officials are worried about “hundreds” of new cases daily.

South Korea is planning to secure convalescent plasma treatments by the end of the year. I spoke to Morning Wave in Busan (a South Korean radio show) explaining what convalescent plasma is, what we know about it, and what we don’t know (52 min in)

It is sea otter awareness week! In addition to being fluffy and playful, sea otters are tenacious as hell. They do not let dire circumstances discourage them; when the species was almost wiped out by humans, sea otters persisted. We should all strive to be more like them. (Published Oct. 2018).

A gif of a sea otter floating in water. The otter is rubbing her face with her paws and it looks like she’s smiling.

There’s a dearth of joy right now. It’s high time we make our own. For Quartz Membership, I wrote about how working from home made me rethink my wardrobe not just for being comfy, but for being joyful. My outfits now proudly channel Ms. Frizzle of Magic School Bus fame. (Or a frat boy about to go hit the gym. These are my two moods now.)

A bathroom mirror selfie of me wearing a yellow, pink, and purple A-line silk dress. The print is of a retina.

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

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Top image by E. Y. Smith, headshot drawing by Richard Howard.