First case of COVID-19 reinfection reported in Hong Kong

The patient's second infection was asymptomatic, suggesting that subsequent infections may be milder.

Doctors treat COVID-19 patient.

Doctors treat COVID-19 patients in an intensive care unit at the third Covid 3 Hospital in Italy.

(Photo by Antonio Masiello/Getty Images)
  • A 33-year-old man contracted the virus first in March, then again in August.
  • Researchers at the University of Hong Kong compared the RNA of the two infections, finding them to be distinct.
  • The immune system's response to the coronavirus remains unclear, but recent studies suggest T cells may help to battle subsequent infections even after antibody levels drop.

A man in Hong Kong was infected with SARS-CoV-2 for a second time, becoming the first confirmed case of reinfection, according to researchers at the University of Hong Kong.

The patient is a 33-year-old man who first contracted the virus in March, and then again more than four months later while traveling in Europe. Since the coronavirus was first reported, scientists have been trying to figure out whether it's possible to contract the virus multiple times, as is possible with other coronaviruses.

But despite some anecdotal reports of reinfection, the Hong Kong patient is the first confirmed case. To make sure the second infection was unrelated to the first, the researchers sequenced the virus from both infections and compared the RNA. They found a significant difference between the samples.

"This is the world's first documentation of a patient who recovered from Covid-19 but got another episode of Covid-19 afterwards," the researchers said in a statement.

On one level, it may be discouraging to learn that it's possible to contract SARS-CoV-2 twice. But the researchers noted that the Hong Kong case might be an outlier, and that reinfection could be rare throughout the population. What's more, the paper described the patient's first case as mild and his second case as asymptomatic.

That's promising news, because it suggests that while the patient's immunity wasn't strong enough to prevent infection, it was strong enough to protect him from developing COVID-19, the disease caused by the virus.

Still, the processes behind the immune response to the virus remain unclear. Earlier in August, the Centers for Disease Control and Prevention issued new guidelines saying that immunity from COVID-19 likely only lasts three months after contraction, while studies have suggested that antibodies seem to fade away after a few months.

But antibodies aren't the whole story. The immune system also has T cells and B cells — the so-called "memory" cells that are able to remember a virus, and then strategically mobilize the immune system against it if it enters the body again. That may help to explain why the Hong Kong patient's second infection was asymptomatic.

Coronavirus researchResearchers Work On Developing Test For Coronavirus At Hackensack Meridian's Center For Discovery and Innovation

(Photo by Kena Betancur/Getty Images)

It'll take time to know how common reinfection is, how durable the immune response is, and how the inevitable mutation of the virus impacts efforts to develop a vaccine.

"It may be completely different with this coronavirus," Dr. Anthony Fauci, who heads the National Institute of Allergy and Infectious Diseases, said in an interview with the medical journal JAMA. "It may be that people induce a response that's quite durable. But if it acts like common coronaviruses, it likely is not going to be a very long duration of immunity."


This is what aliens would 'hear' if they flew by Earth

A Mercury-bound spacecraft's noisy flyby of our home planet.

Image source: sdecoret on Shutterstock/ESA/Big Think
Surprising Science
  • There is no sound in space, but if there was, this is what it might sound like passing by Earth.
  • A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
  • Yes, in space no one can hear you scream, but this is still some chill stuff.

First off, let's be clear what we mean by "hear" here. (Here, here!)

Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.

All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.

BepiColombo

Image source: European Space Agency

The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.

Into and out of Earth's shadow

In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.

The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."

In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."

When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.

Magentosphere melody

The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.

BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.

MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.

Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.

Learn the Netflix model of high-performing teams

Erin Meyer explains the keeper test and how it can make or break a team.

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  • There are numerous strategies for building and maintaining a high-performing team, but unfortunately they are not plug-and-play. What works for some companies will not necessarily work for others. Erin Meyer, co-author of No Rules Rules: Netflix and the Culture of Reinvention, shares one alternative employed by one of the largest tech and media services companies in the world.
  • Instead of the 'Rank and Yank' method once used by GE, Meyer explains how Netflix managers use the 'keeper test' to determine if employees are crucial pieces of the larger team and are worth fighting to keep.
  • "An individual performance problem is a systemic problem that impacts the entire team," she says. This is a valuable lesson that could determine whether the team fails or whether an organization advances to the next level.
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