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It’s Your Brain’s Fault You Make The Same Mistakes Over and Over
Already-created neural pathways make it hard to correct our mistakes going forward.
Image source: giphy
Okay, this is getting confusing. First we didn't want to make mistakes. Then we realized mistakes are great teachers since they provide us lessons we wouldn't think to learn on purpose—I actually told my five-year-old this last week. And now The Atlantic reports that recent research suggests that mistakes are really hard to keep from repeating. So they're not good. Again.
It has to do with neural pathways that get created as we do things. When we do something right, a pathway is created. Unfortunately, a pathway is also created when we something wrong. We basically build habits this way, both good and bad. So the reason we keep making the same mistakes is that we slip by default back into existing neural pathways.
It's the same phenomenon that means you can only get somewhere by getting lost the same way you did last time, or that you keep putting things down in the same spot until they seem to be lost when in fact they're just underneath the most recent thing you put down.
More significantly, this happens with bigger screwups, like being attracted to the wrong kind of person or other misguided decisions you habitually make. It seems our brains do learn from making mistakes: They learn how to make them.
So—and here's where we contradict everything we thought we knew—it's best not to try and learn from past mistakes because remembering them when we want a do-over encourages our brains to head back down the previous pathway. It's better to think about what we want to accomplish and try to view it from a fresh angle that can lead us down a more successful road. That's a neural pathway you'll happily travel.
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There are 5 eras in the universe's lifecycle. Right now, we're in the second era.
Astronomers find these five chapters to be a handy way of conceiving the universe's incredibly long lifespan.
27 March, 2020
Image based on logarithmic maps of the Universe put together by Princeton University researchers, and images produced by NASA based on observations made by their telescopes and roving spacecraft
Image source: Pablo Carlos Budassi
Surprising Science
- We're in the middle, or thereabouts, of the universe's Stelliferous era.
- If you think there's a lot going on out there now, the first era's drama makes things these days look pretty calm.
- Scientists attempt to understand the past and present by bringing together the last couple of centuries' major schools of thought.
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<p>If you're fortunate enough to get yourself beneath a clear sky in a dark place on a moonless night, a gorgeous space-scape of stars waits. If you have binoculars and point them upward, you're treated to a mind-bogglingly dense backdrop of countless specks of light absolutely everywhere, stacked atop each other, burrowing outward and backward through space and time. Such is the universe of the cosmological era in which we live. It's called the Stelliferous era, and there are four others.</p>
The 5 eras of the universe
<p>There are many ways to consider and discuss the past, present, and future of the universe, but one in particular has caught the fancy of many astronomers. First published in 1999 in their book <a href="https://amzn.to/2wFQLiL" target="_blank"><em>The Five Ages of the Universe: Inside the Physics of Eternity</em></a>, <a href="https://en.wikipedia.org/wiki/Fred_Adams" target="_blank">Fred Adams</a> and <a href="https://en.wikipedia.org/wiki/Gregory_P._Laughlin" target="_blank">Gregory Laughlin</a> divided the universe's life story into five eras:</p><ul><li>Primordial era</li><li>Stellferous era</li><li>Degenerate era</li><li>Black Hole Era</li><li>Dark era</li></ul><p>The book was last updated according to current scientific understandings in 2013.</p><p>It's worth noting that not everyone is a subscriber to the book's structure. Popular astrophysics writer <a href="https://www.forbes.com/sites/ethansiegel/#30921c93683e" target="_blank">Ethan C. Siegel</a>, for example, published an article on <a href="https://www.forbes.com/sites/startswithabang/2019/07/26/we-have-already-entered-the-sixth-and-final-era-of-our-universe/#7072d52d4e5d" target="_blank"><em>Medium</em></a> last June called "We Have Already Entered The Sixth And Final Era Of Our Universe." Nonetheless, many astronomers find the quintet a useful way of discuss such an extraordinarily vast amount of time.</p>The Primordial era
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTEyMi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNjEzMjY1OX0.PRpvAoa99qwsDNprDme9tBWDim6mS7Mjx6IwF60fSN8/img.jpg?width=980" id="db4eb" class="rm-shortcode" data-rm-shortcode-id="0e568b0cc12ed624bb8d7e5ff45882bd" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="1049" />Image source: Sagittarius Production/Shutterstock
<p> This is where the universe begins, though what came before it and where it came from are certainly still up for discussion. It begins at the Big Bang about 13.8 billion years ago. </p><p> For the first little, and we mean <em>very</em> little, bit of time, spacetime and the laws of physics are thought not yet to have existed. That weird, unknowable interval is the <a href="https://www.universeadventure.org/eras/era1-plankepoch.htm" target="_blank">Planck Epoch</a> that lasted for 10<sup>-44</sup> seconds, or 10 million of a trillion of a trillion of a trillionth of a second. Much of what we currently believe about the Planck Epoch eras is theoretical, based largely on a hybrid of general-relativity and quantum theories called quantum gravity. And it's all subject to revision. </p><p> That having been said, within a second after the Big Bang finished Big Banging, inflation began, a sudden ballooning of the universe into 100 trillion trillion times its original size. </p><p> Within minutes, the plasma began cooling, and subatomic particles began to form and stick together. In the 20 minutes after the Big Bang, atoms started forming in the super-hot, fusion-fired universe. Cooling proceeded apace, leaving us with a universe containing mostly 75% hydrogen and 25% helium, similar to that we see in the Sun today. Electrons gobbled up photons, leaving the universe opaque. </p><p> About 380,000 years after the Big Bang, the universe had cooled enough that the first stable atoms capable of surviving began forming. With electrons thus occupied in atoms, photons were released as the background glow that astronomers detect today as cosmic background radiation. </p><p> Inflation is believed to have happened due to the remarkable overall consistency astronomers measure in cosmic background radiation. Astronomer <a href="https://www.youtube.com/watch?v=IGCVTSQw7WU" target="_blank">Phil Plait</a> suggests that inflation was like pulling on a bedsheet, suddenly pulling the universe's energy smooth. The smaller irregularities that survived eventually enlarged, pooling in denser areas of energy that served as seeds for star formation—their gravity pulled in dark matter and matter that eventually coalesced into the first stars. </p>The Stelliferous era
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTEzNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3NTEyMTcwMn0.4VTVjWZOZ6UIQtzWZ4EhwbDkwTkfx_rnFbFwXjTxffM/img.jpg?width=980" id="a66a4" class="rm-shortcode" data-rm-shortcode-id="c8f86bf160ecdea6b330f818447393cd" data-rm-shortcode-name="rebelmouse-image" data-width="481" data-height="720" />Image source: Casey Horner/unsplash
<p>The era we know, the age of stars, in which most matter existing in the universe takes the form of stars and galaxies during this active period. </p><p>A star is formed when a gas pocket becomes denser and denser until it, and matter nearby, collapse in on itself, producing enough heat to trigger nuclear fusion in its core, the source of most of the universe's energy now. The first stars were immense, eventually exploding as supernovas, forming many more, smaller stars. These coalesced, thanks to gravity, into galaxies.</p><p>One axiom of the Stelliferous era is that the bigger the star, the more quickly it burns through its energy, and then dies, typically in just a couple of million years. Smaller stars that consume energy more slowly stay active longer. In any event, stars — and galaxies — are coming and going all the time in this era, burning out and colliding.</p><p>Scientists predict that our Milky Way galaxy, for example, will crash into and combine with the neighboring Andromeda galaxy in about 4 billion years to form a new one astronomers are calling the Milkomeda galaxy.</p><p>Our solar system may actually survive that merger, amazingly, but don't get too complacent. About a billion years later, the Sun will start running out of hydrogen and begin enlarging into its red giant phase, eventually subsuming Earth and its companions, before shrining down to a white dwarf star.</p>The Degenerate era
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTE1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNTk3NDQyN30.gy4__ALBQrdbdm-byW5gQoaGNvFTuxP5KLYxEMBImNc/img.jpg?width=980" id="77f72" class="rm-shortcode" data-rm-shortcode-id="08bb56ea9fde2cee02d63ed472d79ca3" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="810" />Image source: Diego Barucco/Shutterstock/Big Think
<p>Next up is the Degenerate era, which will begin about 1 quintillion years after the Big Bang, and last until 1 duodecillion after it. This is the period during which the remains of stars we see today will dominate the universe. Were we to look up — we'll assuredly be outta here long before then — we'd see a much darker sky with just a handful of dim pinpoints of light remaining: <a href="https://earthsky.org/space/evaporating-giant-exoplanet-white-dwarf-star" target="_blank">white dwarfs</a>, <a href="https://earthsky.org/space/new-observations-where-stars-end-and-brown-dwarfs-begin" target="_blank">brown dwarfs</a>, and <a href="https://earthsky.org/astronomy-essentials/definition-what-is-a-neutron-star" target="_blank">neutron stars</a>. These"degenerate stars" are much cooler and less light-emitting than what we see up there now. Occasionally, star corpses will pair off into orbital death spirals that result in a brief flash of energy as they collide, and their combined mass may become low-wattage stars that will last for a little while in cosmic-timescale terms. But mostly the skies will be be bereft of light in the visible spectrum.</p><p>During this era, small brown dwarfs will wind up holding most of the available hydrogen, and black holes will grow and grow and grow, fed on stellar remains. With so little hydrogen around for the formation of new stars, the universe will grow duller and duller, colder and colder.</p><p>And then the protons, having been around since the beginning of the universe will start dying off, dissolving matter, leaving behind a universe of subatomic particles, unclaimed radiation…and black holes.</p>The Black Hole era
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTE2MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMjE0OTQ2MX0.ifwOQJgU0uItiSRg9z8IxFD9jmfXlfrw6Jc1y-22FuQ/img.jpg?width=980" id="103ea" class="rm-shortcode" data-rm-shortcode-id="f0e6a71dacf95ee780dd7a1eadde288d" data-rm-shortcode-name="rebelmouse-image" data-width="1400" data-height="787" />Image source: Vadim Sadovski/Shutterstock/Big Think
<p> For a considerable length of time, black holes will dominate the universe, pulling in what mass and energy still remain. </p><p> Eventually, though, black holes evaporate, albeit super-slowly, leaking small bits of their contents as they do. Plait estimates that a small black hole 50 times the mass of the sun would take about 10<sup>68</sup> years to dissipate. A massive one? A 1 followed by 92 zeros. </p><p> When a black hole finally drips to its last drop, a small pop of light occurs letting out some of the only remaining energy in the universe. At that point, at 10<sup>92</sup>, the universe will be pretty much history, containing only low-energy, very weak subatomic particles and photons. </p>The Dark Era
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTE5NC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0Mzg5OTEyMH0.AwiPRGJlGIcQjjSoRLi6V3g5klRYtxQJIpHFgZdZkuo/img.jpg?width=980" id="60c77" class="rm-shortcode" data-rm-shortcode-id="7a857fb7f0d85cf4a248dbb3350a6e1c" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="810" />Image source: Big Think
<p>We can sum this up pretty easily. Lights out. Forever.</p><p>Tonight, if it's clear, maybe you want to step outside, take a nice deep breath, and look up, grateful that we are where we are, and <em>when</em> we are, in spite of all the day's hardships. We've got a serious amount of temporal elbow room here, far more than we need, so not to worry, and those stars aren't going anywhere for a long, long time.</p>
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When does an idea die? Plato and string theory clash with data
How long should one wait until an idea like string theory, seductive as it may be, is deemed unrealistic?
03 March, 2021
13-8
- How far should we defend an idea in the face of contrarian evidence?
- Who decides when it's time to abandon an idea and deem it wrong?
- Science carries within it its seeds from ancient Greece, including certain prejudices of how reality should or shouldn't be.
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<p>From the perspective of the west, it all started in ancient Greece, around 600 BCE. This is during the Axial Age, a somewhat controversial term coined by German philosopher Karl Jaspers to designate the remarkable intellectual and spiritual awakening that happened in different places across the globe roughly within the span of a century. Apart from the Greek explosion of thought, this is the time of Siddhartha Gautama (aka the Buddha) in India, of Confucius and Lao Tzu in China, of Zoroaster (or Zarathustra) in ancient Persia—religious leaders and thinkers who would reframe the meaning of faith and morality. In Greece, Thales of Miletus and Pythagoras of Samos pioneered pre-Socratic philosophy, (sort of) moving the focus of inquiry and explanation from the divine to the natural. </p><p>To be sure, the divine never quite left early Greek thinking, but with the onset of philosophy, trying to understand the workings of nature through logical reasoning—as opposed to supernatural reasoning—would become an option that didn't exist before. The history of science, from its early days to the present, could be told as an increasingly successful split between belief in a supernatural component to reality and a strictly materialistic cosmos. The Enlightenment of the 17th and 18th centuries, the Age of Reason, means quite literally 'to see the light,' the light here clearly being the superiority of human logic above any kind of supernatural or nonscientific methodology to get to the "truth" of things.</p>
<blockquote>Einstein, for one, was a believer, preaching the fundamental reasonableness of nature; no weird unexplainable stuff, like a god that plays dice—his tongue-in-cheek critique of the belief that the unpredictability of the quantum world was truly fundamental to nature and not just a shortcoming of our current understanding. </blockquote>
<p>To what extent we can understand the workings of nature through logic alone is not something science can answer. It is here that the complication begins. Can the human mind, through the diligent application of scientific methodology and the use of ever-more-powerful instruments, reach a complete understanding of the natural world? Is there an "end to science"? This is the sensitive issue. If the split that started in pre-Socratic Greece were to be completed, nature in its entirety would be amenable to a logical description, the complete collection of behaviors that science studies identified, classified, and described by means of perpetual natural laws. All that would be left for scientists and engineers to do would be practical applications of this knowledge, inventions, and technologies that would serve our needs in different ways.</p>
<p>This sort of vision—or hope, really—goes all the way back to at least Plato who, in turn, owes much of this expectation to Pythagoras and Parmenides, the philosopher of Being. The dispute between the primacy of that which is timeless or unchangeable (Being), and that which is changeable and fluid (Becoming), is at least that old. Plato proposed that truth was in the unchangeable, rational world of Perfect Forms that preceded the tricky and deceptive reality of the senses. For example, the abstract form <em>Chair</em> embodies all chairs, objects that can take many shapes in our sensorial reality while serving their functionality (an object to sit on) and basic design (with a sittable surface and some legs below it). According to Plato, the Forms hold the key to the essence of all things.</p>
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTcwODg5Ni9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYzNDA3OTQzNX0.Fy8WPmFn0mT0fy5e3Qq3HN70lzJ7Epk2iICVl6BwM_Q/img.png?width=980" id="4f64f" class="rm-shortcode" data-rm-shortcode-id="5a29206a396ef429914fa48a441c00be" data-rm-shortcode-name="rebelmouse-image" data-width="782" data-height="1024" />
Plato used the allegory of the cave to explain that what humans see and experience is not the true reality.
Credit: Gothika via Wikimedia Commons CC 4.0
<p>When scientists and mathematicians use the term <em>Platonic worldview</em>, that's what they mean in general: The unbound capacity of reason to unlock the secrets of creation, one by one. Einstein, for one, was a believer, preaching the fundamental reasonableness of nature; no weird unexplainable stuff, like a god that plays dice—his tongue-in-cheek critique of the belief that the unpredictability of the quantum world was truly fundamental to nature and not just a shortcoming of our current understanding. Despite his strong belief in such underlying order, Einstein recognized the imperfection of human knowledge: "What I see of Nature is a magnificent structure that we can comprehend only very imperfectly, and that must fill a thinking person with a feeling of humility." (Quoted by Dukas and Hoffmann in <em>Albert Einstein, The Human Side: Glimpses from His Archives</em> (1979), 39.)</p> <p>Einstein embodies the tension between these two clashing worldviews, a tension that is still very much with us today: On the one hand, the Platonic ideology that the fundamental stuff of reality is logical and understandable to the human mind, and, on the other, the acknowledgment that our reasoning has limitations, that our tools have limitations and thus that to reach some sort of final or complete understanding of the material world is nothing but an impossible, <a href="https://www.amazon.com/dp/B01K2JTGIA?tag=bigthink00-20&linkCode=ogi&th=1&psc=1" target="_blank" rel="noopener noreferrer">semi-religious dream</a>.</p><p>This kind of tension is palpable today when we see groups of scientists passionately arguing <a href="https://www.amazon.com/dp/0316013331?tag=bigthink00-20&linkCode=ogi&th=1&psc=1" target="_blank">for</a> or <a href="https://www.amazon.com/dp/1541646762?tag=bigthink00-20&linkCode=ogi&th=1&psc=1" target="_blank">against</a> the existence of the multiverse, an idea that states that our universe is one in a huge number of other universes; or <a href="https://www.amazon.com/dp/0735223793?tag=bigthink00-20&linkCode=ogi&th=1&psc=1" target="_blank">for</a> or <a href="https://www.amazon.com/dp/0465092764?tag=bigthink00-20&linkCode=ogi&th=1&psc=1" target="_blank">against</a> the final unification of the laws of physics.</p><p>Nature, of course, is always the final arbiter of any scientific dispute. Data decides, one way or another. That's the beauty and power at the core of science. The challenge, though, is to know when to let go of an idea. How long should one wait until an idea, seductive as it may be, is deemed unrealistic? This is where the debate gets interesting. Data to support more "out there" ideas such as the multiverse or extra symmetries of nature needed for unification models has refused to show up for decades, despite extensive searches with different instruments and techniques. On the other hand, we only find if we look. So, should we keep on defending these ideas? Who decides? Is it a community decision or should each person pursue their own way of thinking?</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="fa3185b1f66d82d9e77023abfa9da5bf"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/YSWd21z2qqE?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>In 2019, I participated in an interesting <a href="https://www.worldsciencefestival.com/programs/loose-ends-string-theory-and-the-quest-for-the-ultimate-theory/" target="_blank">live debate at the World Science Festival</a> with physicists Michael Dine and Andrew Strominger and hosted by physicist Brian Greene. The theme was string theory, our best candidate for a final theory of how particles of matter interact. When I completed my PhD in 1986, string theory was <em>the</em> way. The only way. But, by 2019, things had changed, and quite dramatically, due to the lack of supporting data. To my surprise, both Mike and Andy were quite open to the fact that that certainty of the past was no more. String theory has taught physicists many things and that was perhaps its use. The Platonic outlook was in peril.</p><p>The dispute remains alive, although with each experiment that fails to show supporting evidence for string theory the dream grows harder to justify. Will it be a generational thing, as celebrated physicist Max Planck once quipped, "Ideas don't die, physicists do"? (I paraphrase.) I hope not. But it is a conversation that should be held more in the open, as was the case with the World Science Festival. Dreams die hard. But they may die a little easier when we accept the fact that our grasp of reality is limited, and doesn't always fit our expectations of what should or shouldn't be real.</p>
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Can you still spread coronavirus after getting the vaccine?
The vaccine will shorten the "shedding" time.
03 March, 2021
Fredrik Lerneryd/Getty Images
Coronavirus
Editor's note: So you've gotten your coronavirus vaccine, waited the two weeks for your immune system to respond to the shot and are now fully vaccinated.
<p><em>Does this mean you can make your way through the world like the old days without fear of spreading the virus? <a href="https://scholar.google.com/citations?user=eNprtJEAAAAJ&hl=en&oi=ao">Deborah Fuller is a microbiologist</a> at the University of Washington School of Medicine working on coronavirus vaccines. She explains what the science shows about transmission post-vaccination – and whether new variants could change this equation.</em></p><h2>1. Does vaccination completely prevent infection?</h2><p>The short answer is no. You can still get infected after you've been vaccinated. But your chances of getting seriously ill are almost zero.</p><p>Many people think vaccines work like a shield, blocking a virus from infecting cells altogether. But in most cases, a person who gets vaccinated is <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/sterilizing-immunity">protected from disease, not necessarily infection</a>.</p><p>Every person's immune system is a little different, so when a vaccine is <a href="https://www.nytimes.com/2020/11/20/health/covid-vaccine-95-effective.html">95% effective</a>, that just means 95% of people who receive the vaccine <a href="https://doi.org/10.1056/NEJMoa2101765">won't get sick</a>. These people could be completely protected from infection, or they could be getting infected but remain asymptomatic because their immune system eliminates the virus very quickly. The remaining 5% of vaccinated people can become infected and get sick, but are <a href="https://doi.org/10.1056/NEJMoa2101765">extremely unlikely to be hospitalized</a>. </p><p>Vaccination doesn't 100% prevent you from getting infected, but in all cases it gives your immune system a huge leg up on the coronavirus. Whatever your outcome – whether complete protection from infection or some level of disease – you will be better off after encountering the virus than if you hadn't been vaccinated.</p><p> <a href="https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An electron microscope scan of the coronavirus" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=469&fit=crop&dpr=1 600w, https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=469&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=469&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=589&fit=crop&dpr=1 754w, https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=589&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/386271/original/file-20210224-22-1uk65si.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=589&fit=crop&dpr=3 2262w"></a></p><p> Vaccines prevent disease, not infection. (<a class="source" href="https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2#/media/File:Novel_Coronavirus_SARS-CoV-2.jpg">National Institute of Allergy and Infectious Diseases</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a>)</p>
<h2>2. Does infection always mean transmission?</h2><p>Transmission happens when enough viral particles from an infected person get into the body of an uninfected person. In theory, anyone infected with the coronavirus could potentially transmit it. But a vaccine will reduce the chance of this happening.</p><p>In general, if vaccination doesn't completely prevent infection, it will significantly reduce the amount of virus coming out of your nose and mouth – a process called shedding – and shorten the time that you shed the virus. This is a big deal. A person who sheds less virus is <a href="https://www.scientificamerican.com/article/vaccines-need-not-completely-stop-covid-transmission-to-curb-the-pandemic1/" target="_blank" rel="noopener noreferrer">less likely to transmit it to someone else</a>.</p><p>This seems to be the case with coronavirus vaccines. In a <a href="https://doi.org/10.1101/2021.02.06.21251283" target="_blank" rel="noopener noreferrer">recent preprint study</a> which has yet to be peer reviewed, Israeli researchers tested 2,897 vaccinated people for signs of coronavirus infection. Most had no detectable virus, but people who were infected had one-quarter the amount of virus in their bodies as unvaccinated people tested at similar times post-infection.</p><p>Less coronavirus virus means less chance of spreading it, and if the amount of virus in your body is low enough, the probability of transmitting it may reach almost zero. However, researchers don't yet know where that cutoff is for the coronavirus, and since the vaccines don't provide 100% protection from infection, the Centers for Disease Control and Prevention recommends that people continue to wear masks and social distance even <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/keythingstoknow.html" target="_blank" rel="noopener noreferrer">after they've been vaccinated</a>.</p>
<h2>3. What about the new coronavirus variants?</h2><p>New variants of coronavirus have emerged in recent months, and recent studies show that vaccines are less effective against certain ones, like <a href="https://www.cidrap.umn.edu/news-perspective/2021/02/pfizer-moderna-vaccines-may-be-less-effective-against-b1351-variant" target="_blank" rel="noopener noreferrer">the B1351 variant</a> first identified in South Africa.</p><p>Every time SARS-CoV-2 replicates, it gets new mutations. In recent months, researchers have found new variants that are <a href="https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/scientific-brief-emerging-variants.html" target="_blank" rel="noopener noreferrer">more infective</a> – meaning a person needs to breathe in less virus to become infected – and other variants that are <a href="https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiab082/6134354" target="_blank" rel="noopener noreferrer">more transmissible</a> - meaning they increase the amount of virus a person sheds. And researchers have also found at least one new variant that seems to be <a href="https://doi.org/10.1101/2021.02.14.21251704" target="_blank" rel="noopener noreferrer">better at evading the immune system</a>, according to early data.</p><p>So how does this relate to vaccines and transmission?</p>
<p>For the South Africa variant, vaccines still provide <a href="https://www.sciencemag.org/news/2021/01/one-dose-covid-19-vaccine-offers-solid-protection-against-severe-disease" target="_blank">greater than 85% protection</a> from getting severely ill with COVID–19. But when you count mild and moderate cases, they provide, at best, only about <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00370-6/fulltext" target="_blank">50%-60% protection</a>. That means at least 40% of vaccinated people will still have a strong enough infection – and enough virus in their body – to cause at least moderate disease.</p><p>If vaccinated people have more virus in their bodies and it takes less of that virus to infect another person, there will be higher probability a vaccinated person could transmit these new strains of the coronavirus.</p><p>If all goes well, vaccines will very soon reduce the rate of severe disease and death worldwide. To be sure, any vaccine that reduces disease severity is also, at the population level, reducing the amount of virus being shed overall. But because of the emergence of new variants, vaccinated people still have the potential to shed and spread the coronavirus to other people, vaccinated or otherwise. This means it will likely take <a href="https://www.scientificamerican.com/article/vaccines-need-not-completely-stop-covid-transmission-to-curb-the-pandemic1/" target="_blank">much longer for vaccines to reduce transmission</a> and <a href="https://doi.org/10.1038/d41586-021-00396-2" target="_blank" rel="noopener noreferrer">for populations to reach herd immunity</a> than if these new variants had never emerged. Exactly how long that will take is a balance between how effective vaccines are against emerging strains and how transmissible and infectious these new strains are.</p><p><a href="https://theconversation.com/profiles/deborah-fuller-1207799" target="_blank" rel="noopener noreferrer">Deborah Fuller</a>, Professor of Microbiology, School of Medicine, <em><a href="https://theconversation.com/institutions/university-of-washington-699" target="_blank" rel="noopener noreferrer">University of Washington</a></em></p><p>This article is republished from <a href="https://theconversation.com/" target="_blank" rel="noopener noreferrer">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/can-vaccinated-people-still-spread-the-coronavirus-155095" target="_blank" rel="noopener noreferrer">original article</a>.</p>
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