Welcome to brain Stuff production of I Heart Radio. Hey brain Stuff, Lauren Bogle Bomb here Today we're kicking off mini series of health and safety topics surrounding the novel type of coronavirus identified in which causes what's therefore being called COVID nineteen. Because everything is a little less scary when you understand it better. So first up, let's talk
about how long viruses can live on surfaces. Because between all those door handles, credit card keypads, and even our own cell phones, we interact with so many surfaces daily. I mean, even if you don't hand your phone over to everyone you meet, you probably put it down on, say, a table that other people have touched. And that's a
fact of life. But some of what we colloquially call germs, that is viruses, bacteria, and other microbes that can cause infections in our bodies, some germs can survive on surfaces outside of our bodies long enough to spread from one person to another. There's unfortunately no hard and fast rule for how long viruses in general can live on surfaces. Part of the uncertainty is because viruses are diverse and
have a variety of surface survival rates. The type of surface, and environmental temperature and humidity all come into play too, so which surfaces are safe to touch and how often do we need to disinfect them? But wait, let's back up a step. What are viruses and are they even alive in the first place. Things that we generally consider to be living have the more or less standalone ability
to eat, grow, and reproduce. A single celled bacterium or fungi, or even a cell from your body can do all those things because they contain the genetic instructions to do so, plus the enzymes to carry out those instructions. But viruses don't. They have the genetic instructions the DNA or RNA, but they don't have the right enzymes to create the chemical reactions necessary for reproduction. Instead, viruses need a host cell, which can be bacteria, fungi, or a planter animal including
a human. Virus will attack a host cell and release its genetic instructions, which hijack the host cells enzymes to make new viruses. That's good for the virus but generally bad for the host. Without a host cell, a virus can't survive long term. However, it does have a short window of time during which it can stay functional in hopes of infecting a new host and attaching to a
host cell. Outside of a host, viruses can either stay intact and remain infectious, or they can degrade to the point that they're merely identifiable, which means that you'll still be able to identify them from their genetic material, but they won't be capable of seeking out and attacking host cells. At the point that a virus on a surface is only identifiable, it won't be able to cause harm. The length of time that viruses can remain infectious on surfaces
varies greatly. There are baseline differences between viruses. For example, rhinoviruses, the viruses that are mostly responsible for the common cold, will last for less than an hour on surfaces. Others, such as the norovirus, which is a virus that can cause vomiting and diarrhea, can last for weeks, which is why noravirus can easily spread both through infected people and through contaminated foods and surfaces. There are several types of coronaviruses.
Most cause mild symptoms and are responsible, along with rhinoviruses, for the common cold, but three types are known for causing more serious diseases mers, SARS and COVID nineteen, and because the coronavirus that causes COVID nineteen is novel, the research into how long it can last on surfaces is
new and ongoing. A study published online on marcht by researchers at the National Institutes of Health, the US Centers for Disease Control and Prevention, and multiple universities compared the novel coronavirus with the coronavirus that causes severe acute respiratory syndrome or STARS. This is the most closely related human coronavirus to COVID nineteen and was responsible for the two
thousand three epidemic. This study, which has not been peer reviewed as of this recording, found that the two viruses have similar viability in the environment, which is to say, not a whole whole lot something between rhinovirus and neurovirus.
The study determined that novel coronavirus could remain infectious for up to three days on stainless steel and plastic surfaces, but survival on other surfaces was lower, just one day on cardboard and four hours on copper, and it was lowest of all in the air just up to three hours, but keep in mind that these numbers are the maximum for the viability of the virus. Viruses start to degrade
pretty immediately when they're not in a host. The longer they're in the air or on a surface, exponentially fewer of them will remain infectious. And if your imman system is working okay, a lot of individual viruses need to get into your body, either via your mucous membranes like your eyes, nose, and mouth, or via cuts in your skin in order for you to get infected. That's why direct person to person contact is still the easiest way for coronavirus to spread, and why everyone's telling you to
wash your hands before touching your face. It's also why we don't have more precise numbers for how long coronavirus, or any virus for that matter, no matter how long they've been studied, can last on surfaces. We spoke via email with Dr Alicia Kray, postdoctoral fellow in epidemiology at
Emory University. She said, generally, survival of pathogens on famites, which are objects or materials likely to carry infection, is determined by inoculating a surface with a known quantity of virus and then sampling at various time intervals to determine the amount recovered. Scientists use this information to estimate a decay curve for the pathogen on the particular surface, which
can be extrapolated to longer time in vals. The NIH and CDC team that studied surface variation for coronavirus is still researching. They're looking into coronavirus viability from snott versus flegm versus poop, as well as in varying environmental conditions. Because although viruses have differing baseline rates of survival on surfaces, additional factors affect their ability to endure outside of a host, like temperature, humidity, and properties of the surface itself, Cray said.
In general, viruses survive longest at lower temperatures, higher humidity, and on non porous surfaces like stainless steel. However, some viruses do well at low humidity. There have been a lot of theories about whether coronavirus will lessen during warmer months because dry, cold air like in the winter tends to provide favorable conditions for flu transmission, but we simply
don't know yet. Dr Anthony Fossey, Director of the National Institute of Allergy and Infectious Diseases explained during the March thirteen, twenty c in Facebook Global Coronavirus town Hall that when considering the viability of a virus on various substances, it's probably measured in a couple hours. While he recommends wiping down surfaces like door knobs and cell phone screens when you can, he cautioned against worrying about things like money
and mail in the end. Despite the differences in viability on surfaces among pathogens, fomites, and contexts, the number one recommendation for preventing the spread of viruses is standard if you've touched a shared surface, wash your hands before you touch your face or any part of your body that might have a cut or other skin abrasion. The human skin is great at keeping out cold and flu viruses thanks to its pH and porous nature. They survive for
only about twenty minutes on our hands. Today's episode was written by Carrie Whitney, PhD and produced by Tyler Clang. For more on this and lots of other topics, visit how stuff works dot com. Brain Stuff is production of I heart Rate Dio. For more podcasts. For my heart Radio, visit the heart Radio app, Apple podcasts, or wherever you listen to your favorite shows.