Katherine J. Wu

Every drop of pus that’s squeezed out of the human body is a squidgy mess—a souvenir of an infection gone awry, a reminder to never eat off-color custard again. It is also a wartime memorial, dedicated to the corpses of the many thousands of microscopic soldiers that once teemed within. The fallen are neutrophils: stalwart immune cells that throng in the blood by the mind-boggling billions, waiting to rush to sites of injury or infection as a first line of defense.

Mangrove rivulus fish hate enforced water aerobics. Despite her best efforts, Giulia Rossi, a biologist who recently received her doctorate from the University of Guelph, cannot coax the fish to swim against a current in a laboratory tank. “They refuse to exercise in water,” she told me. “They just let themselves hit the back mesh.”When plucked out of water, however, the stubborn swimmers quickly whip themselves into shape.

The best immune systems thrive on a healthy dose of paranoia. The instant that defensive cells spot something unfamiliar in their midst—be it a living microbe or a harmless mote of schmutz—they will whip themselves into a frenzy, detonating microscopic bombs, sparking bouts of inflammation, even engaging in some casual cannibalism until they are certain that the threat has passed.

The trunk of an African elephant is an evolutionary marvel. Clocking in at weights well over 200 pounds, it ripples with thousands of individual muscles that help the superlong schnoz lift barbells, uproot trees, and fling bothersome lions into the air.
A tortilla chip is an embarrassment of engineering.

With 165 million people and counting inoculated in the United States, vaccines have, at long last, tamped the pandemic’s blaze down to a relative smolder in this part of the world. But the protection that vaccines offer is more like a coat of flame retardant than an impenetrable firewall. SARS-CoV-2 can, very rarely, still set up shop in people who are more than two weeks out from their last COVID-19 shot.These rare breakthroughs, as I’ve written before, are no cause for alarm.

In many, many ways, fish of the species Brienomyrus brachyistius do not speak at all like Barack Obama. For starters, they communicate not through a spoken language but through electrical pulses booped out by specialized organs found near the tail. Their vocabulary is also quite unpresidentially poor, with each individual capable of producing just one electric wave—a unique but monotonous signal.

In the race to build the world’s first round of coronavirus vaccines, the spike protein—the thorny knobs that adorn each of the pathogen’s particles—was our MVP. Spike is a key ingredient in virtually every one of our current pandemic-fighting shots; it has been repeatedly billed as essential for tickling out any immune response worth its salt. “People put all their eggs in the spike basket,” Juliet Morrison, a virologist at UC Riverside, told me.

Deep in the forests of Germany, nestled neatly into the hollowed-out shells of acorns, live a smattering of ants who have stumbled upon a fountain of youth. They are born workers, but do not do much work. Their days are spent lollygagging about the nest, where their siblings shower them with gifts of food. They seem to elude the ravages of old age, retaining a durably adolescent physique, their outer shells soft and their hue distinctively tawny.

Arne Svenson, Stray #55
To peer into the soul of a sea cucumber, don’t look to its face; it doesn’t have one. Gently turn that blobby body around, and gaze deep into its marvelous, multifunctional anus.The sea cucumber’s posterior is so much more than an exit hole for digestive waste.

In preparation for birth, some expectant human parents will build IKEA cribs or down prenatal vitamins. Female hoopoes douse their eggs in a pungent postcoital goo.Shortly after laying their eggs, these delightfully zebra-striped birds will begin to paint the clutch with their beak. The pigment they use is made in-house—a brown, oily substance secreted by the uropygial gland, located at the base of the female’s tail.

Updated at 4:39 p.m. ET on April 29, 2021.On my kitchen wall hangs a very small and very adorable cat calendar, with May 23 circled in Sharpie. It’s the day my Pfizer vaccine will, at long last, blossom into “full vaccination,” as sanctioned by the CDC. I’ll be able to safely venture outdoors unmasked and skip post-exposure quarantines.

In the summer of 2009, when Diana was three and a half years old, her health took a tumble. She began to run high fevers and vomit, and gain weight at a baffling pace. She made several trips to the emergency room over the course of two months before doctors finally diagnosed her with two rare, life-threatening conditions. The first, atypical hemolytic uremic syndrome, went after her kidneys, “and really messed them up,” Diana told me.

If the immune system ran its own version of The Bachelor, antibodies would, hands down, get this season’s final rose.These Y-shaped molecules have acquired some star-caliber celebrity in the past year, due in no small part to COVID-19. For months, their potentially protective powers have made headlines around the globe; we test for them with abandon, and anxiously await the results.

The Johnson & Johnson shot is teetering on the precipice of becoming America’s “dudes only” vaccine. On Tuesday, the CDC and FDA advised halting the vaccine’s nationwide rollout to investigate six cases of a rare blood-clotting disorder that’s occurred in people within about two weeks of receiving the vaccine—all of them women under the age of 50.

For most ant species, nothing spells apocalypse quite like the death of a queen. A colony stripped of its monarch, the group’s only fertile female and the sole source of eggs, quickly unravels, then extinguishes—an entire society snuffed out. The captain does not go down with her ship; the ship goes down with her captain.Indian jumping ants do not abide by such dictatorial dramatics. They’ve evolved a work-around to indefinitely forestall their colonies’ demise.

The Johnson & Johnson vaccine has entered regulatory purgatory. This morning, the CDC and FDA jointly recommended, “out of an abundance of caution,” a nationwide halt to the single shot’s rollout. The two agencies are investigating a rare blood-clotting disorder: In the six cases reported so far, all in the United States, women ages 18 to 48 developed an unusual type of blood clot within about two weeks of receiving the company’s inoculation.

A lot can change in 17 years. The last time the cicadas were here, the virus behind the SARS outbreak had finally retreated. George W. Bush was campaigning for his second presidential term, and Myspace had commenced its meteoric rise. Tobey Maguire was still the reigning Spider-Man.

A few weeks ago, my partially vaccinated partner and my wholly unvaccinated self got an invitation to a group dinner, held unmasked and indoors. There’d be Thai food for 10, we were promised, and two über-immunized hosts, more than two weeks out from their last Moderna doses. And what about everyone else? I asked. Would they be fully vaccinated, too?Well, came the response. Not really. Some would be, some wouldn’t.

Updated at 5:57 p.m. on March 31, 2020.One year ago, around the end of March, Carly Taylor received a positive result for two tests in two consecutive weeks. The first was a test for the new coronavirus. The second was a pregnancy test.Her daughter, Ophelia, arrived on December 22, within days of the public debut of the first COVID-19 vaccines in the United States.

For much of 2020, the world pinned its collective post-pandemic plans on a single, glimmering end point: the arrival of an effective COVID-19 vaccine. The resounding refrain of “when I’m vaccinated” has long conjured images of people shedding their masks, hugging their friends, and returning to a semblance of normalcy. And now some vaccinated people are doing exactly that.

The aptly named cone snail wears a house that resembles a Ben & Jerry’s receptacle, filled not with ice cream but with a squishy mollusk that sports an extendable, trunklike proboscis. The snails are superficially docile creatures, and can be painfully shy; sometimes they go weeks in a lab without taking a single bite of food, cringing at the slightest change in temperature, lighting, or human supervision.

Before frat parties, there were frog ponds.Literal breeding grounds for some of the world’s noisiest bachelors, these lusty pools are where amphibians gather to woo mates. And as any frog researcher will tell you, they’re “super, super, super loud,” says Valentina Caorsi, a bioacoustician at the University of Trento in Italy.

The world of Danish children’s television is not for the prudish. Kids who turn on the tube in Denmark might be greeted by gratuitous flatulence, cursing, casual nudity, or cross-dressing puppets. , a free-spirited, open-minded approach to life—kids begin discussing love, sexuality, relationships, and consent as early as kindergarten, learning while young that their bodies are things to be acknowledged, not repressed.

On its face, reinfection appears to be a straightforward term. It is literally “infection, again”—a recovered person’s second dalliance with the same microbe. Long written into the scientific literature of infectious disease, it is a familiar word, innocuous enough: a microbial echo, an immunological encore act.But thanks to the pandemic, reinfection has become a semantic and scientific mess.

To locate some of the world’s most superpowered cells, look no further than the human immune system. The mission of these hometown heroes is threefold: Memorize the features of dangerous microbes that breach the body’s barriers. Launch an attack to bring them to heel. Then squirrel away intel to quash future assaults.The immune system is comprehensive, capable of dueling with just about every microbe it meets.