Jun 17, 2021

Axios Science

Thanks for reading Axios Science. This week's newsletter — about a new virus variant in the U.S., rivers that run dry and more — is 1,490 words, a 5½-minute read.

1 big thing: Another coronavirus variant gains a foothold

Illustration: Sarah Grillo/Axios

Public health officials are renewing calls for COVID-19 vaccinations, as a more infectious variant that can be thwarted with available vaccines is spreading rapidly in the United States, Eileen Drage O'Reilly and I write.

Why it matters: The B.1.617.2 (or Delta) variant was first detected in India and is expected to become the dominant strain in the U.S. in three to four weeks, some researchers say. If vaccination rates continue to slow, the variant could fuel surges in pockets of the country this fall.

  • More transmissible variants continue to supplant previously dominant strains, raising the stakes for people who aren't vaccinated and reminding Americans that the pandemic isn't over — a fact many other countries still face.
  • The steady uptick in B.1.617.2 "very much mirrors what happened in the United Kingdom about a month ago. And so I fully expect that sometime in the next three or four weeks, the Delta variant will be the dominant SARS-CoV-2 lineage in the U.S.," says Andrew Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health.

By the numbers: The CDC — which listed B.1.617.2 as a variant of concern this week — says it was responsible for about 10% of new COVID-19 cases in the U.S. for the two-week period ending June 5. This compares to 2.7% of cases in the prior two-week period.

  • The variant appears to be about 64% more transmissible than the most common variant right now in the U.S., B.1.1.7 (or Alpha variant first found in the U.K.), which itself was roughly 50% more transmissible than earlier strains.
  • And early data from England and Scotland indicate the risk of hospitalization from B.1.617.2 was twice that of B.1.1.7. But experts caution more data is needed to determine the severity of disease caused by the variant.

Details: The variant — like others before it — has genetic mutations that have been found to enhance the virus' binding to the surface of a host's cells, MIT Tech Review reports.

  • But B.1.617.2 also has a mutation that preliminary experiments suggest may make it more efficient for the virus to be cleaved in a specific location — a key step in the process of a virus entering the cell where it replicates.
  • The next steps are to determine whether that change translates into having an impact on where the virus replicates in the lungs and airways, which affects its transmissibility and the severity of disease it causes, Vineet Menachery, a virologist at the University of Texas Medical Branch, tells Axios.

The big picture: B.1.617.2 fueled India's devastating outbreak this spring and has since been detected in more than 80 countries.

  • On Monday, U.K. Prime Minister Boris Johnston extended the country's COVID-19 restrictions, citing the rapid spread of the variant, which is responsible for about 90% of new cases there.

In the U.S., public health experts warn the variant poses a risk to people who are unvaccinated. While a national surge is unlikely given parts of the country have high rates of vaccination, variants could fuel local and regional outbreaks, particularly in the South.

  • "We have a mistaken belief [the pandemic] is over here, but there are over 100 counties where less than 20% of the people have one dose of vaccine," says Michael Osterholm, director of the University of Minnesota's Center for Infectious Disease Research and Policy.
  • Hot spots may start popping up this fall, as those who remain unvaccinated start congregating indoors and schools begin a new year, Pekosz tells Axios.

What to watch: This won't be the last SARS-CoV-2 variant, and others could be more severe. "The challenge is what is the next variant going to look like," Osterholm says.

2. Catch up quick on COVID-19

Illustration: Sarah Grillo/Axios

More than 600,000 people in the U.S. have died from COVID-19.

Some Americans were infected with SARS-CoV-2 in December 2019, Eileen reports.

Novavax announced its COVID-19 vaccine has a 90% overall efficacy against SARS-CoV-2, per Axios' Yacob Reyes.

The U.S. government is directing more than $3 billion toward the development of antiviral drugs for early treatment of COVID-19, the NYT's Carl Zimmer reports. (Go deeper: The hunt for COVID-10 antiviral drugs)

3. Where rivers run dry

Clauge River in Jura, France, in nonflowing phase. Photo: Bertrand Launay/National Research Institute for Agriculture, Food and Environment

A new detailed map reveals more than half of the world’s network of rivers and streams runs dry for at least one day each year.

Why it matters: Knowing how often and for how long rivers stop flowing is important for managing water resources and conserving species adapted to these unique ecosystems, but so-called nonperennial rivers are understudied and often overlooked.

How it works: Small streams carry organic matter and nutrients to larger rivers, lakes and the ocean.

  • “They are what connects a lot of the terrestrial environment to the freshwater environment,” says Mathis Loïc Messager of McGill University and the National Research Institute for Agriculture, Food and Environment in Villeurbanne, France, who is an author of the new study.
  • Some of these rivers and streams stop flowing naturally — due to winter freezing in some places and dry seasons in others — but also from overuse for irrigation and other purposes.

What they found: Most types of rivers and streams in the world flow intermittently.

  • Messager and his colleagues got a handle on the distribution of nonperennial rivers and streams by first pairing water flow measurements from 5,615 stations around the world with data about the climate, soil, geology, land cover around the rivers and other environmental variables at those collection sites.
  • The researchers then extrapolated that model of where rivers run dry and estimated between 51% and 60% of the world's 40 million miles of mapped rivers and streams stop flowing for at least one day each year.
  • And between "44% and 53% of the global river network ceases to flow at least one month per year," they report this week in Nature.
  • Nonperennial streams and rivers were found across all climates — from parts of the Niger River in West Africa to the headwaters of the Amazon. The team estimates for "52% of the world’s population in 2020, the nearest river or stream is nonperennial."

What's next: The researchers are working on estimating how human activities, in particular agriculture and energy generation, have impacted the distribution of nonperennial rivers and how climate change may impact them in the future.

  • Climate change-fueled droughts in Australia and parts of Africa could cause more rivers there to flow intermittently in the future.
  • But it isn't just rivers drying up: Rising temperatures in the Arctic may mean rivers that typically freeze and stop flowing in the winter may not anymore, Messager says.

"Now that we know these are a really important part of the global river network and the role of rivers in the global carbon cycle, we have to catch up," Messager says.

  • There is a need for tools and protocols to monitor the health of these rivers and for water use guidelines to take into account that a river's flow can go to zero, he adds. "We need to speak in new terms."
4. Worthy of your time

Scientists discover a new plant organ (Shi En Kim — Smithsonian)

Aging process is unstoppable, unprecedented study finds (Amelia Hill — The Guardian)

The lithium mine versus the wildflower (Gregory Barber — Wired)

Evolution of the dad (Elizabeth Preston — Knowable)

5. Something wondrous

Photo: Nicholas Naclerio/University of California, Santa Barbara

Borrowing techniques from burrowing animals and plant roots, researchers have developed a soft robot that can move through sand.

Why it matters: The robot can go where others before it struggled — underground where soil, sand and other matter strongly restrict movement — and it could be used to explore other planets, or install irrigation, its developers say.

How it works: The robot, developed by researchers at the University of California-Santa Barbara and Georgia Institute of Technology, grows from a pneumatic tip on one end — mimicking the growth of plant roots — while the rest stays still, eliminating friction along most of its body.

  • The design, an upgrade from an earlier version, also borrows a technique from burrowing octopuses to reduce drag: The researchers blow air out of the tip of the robot to fluidize the sand so it is easier to move through.
  • And by using an asymmetric tip similar in shape to the head of sandfish lizards and blowing sand downward from it, the robot can stay on its path despite lift forces created by the sand.
  • "Tendons" that run along the length of the body are shortened to turn the tip.

The robot can move nearly 16 feet per second, veer and burrow, Nicholas Naclerio of UC Santa Barbara and his colleagues report in Science Robotics.

  • On speed, it "outperforms all other existing burrowing robots and probably all burrowing organisms, but not without cost," Junliang Tao of Arizona State University, who wasn't involved in the research, writes in a commentary about the study.
  • The energy required to blow the sand "can be hundreds of times more than that saved from the reduction of drag," he writes.
  • "Future work could examine integrating tip extension with conventional drilling and exploration technologies," the study authors suggest.