Coronavirus Transmission: Where the Virus Goes in your Body and How it is Spread

 

You may be wondering where the novel coronavirus (called SARS-CoV-2) is hiding out all around you, especially when you have to go out in public – what is ‘safe’ to do and to touch? (When in doubt, wash your hands and sanitize the surface!)

To better understand what we should pay attention to, we need to know what parts of the body the virus infects and how it is transmitted from person to person. It is important to remember that this is a new virus, so researchers are constantly learning more about it every day.

Where in the body is coronavirus?

Like kids used to search the world for Carmen Sandiego (shoutout to anyone who remembers playing that game!), scientists have sleuthed out where coronavirus hides in our bodies. If we know where the virus hides (aka the types of tissues it infects), we can learn about how the virus is spread. Check out this Science article for an interactive graphic showing where the coronavirus infects the body (and see the image adapted from the article below).

Covid 19

How the novel coronavirus (SARS-CoV-2) affects different parts of the body. Source: Science

 

Since it is a respiratory virus, we know that it infects the respiratory tract (the nose and lungs), causing coughing, shortness of breath, and difficulty breathing. Some patients with coronavirus disease 2019 (COVID-19), the disease caused by the novel coronavirus, have reported loss of smell or taste, possibly due to the virus infecting and damaging nerve cells in the nose and mouth. Sicker COVID-19 patients can also have conjunctivitis (also called pink eye).

But COVID-19 patients also have some symptoms you wouldn’t readily link to a respiratory infection. The virus uses a certain human cell receptor, called angiotensin converting enzyme 2 (ACE2), to enter into the cell. The ACE2 receptor is expressed on cells in the lungs, nose, blood vessels, intestines, and some parts of the brain. This could explain the otherwise unexpected COVID-19 symptoms, such as blood clots, heart attacks, heart inflammation, diarrhea, strokes, seizures, confusion, and brain inflammation.

Can you get coronavirus from that?!

Now that we know coronavirus infects the nose, lungs, and intestines, let’s think about ways the virus can spread from one person to another.

Let’s start with the obvious. Since it is a respiratory virus, you can spread coronavirus through your nose and mouth. Sneezing, coughing, yelling, and even talking (yes, just talking!) could expel respiratory droplets, which can contain the virus if you’re infected. These virus-containing droplets can travel 3 feet in the air, meaning you can breathe in the virus from the air around an infected person.

Coronavirus can also live for up to 3 hours in the air, so you could breathe in the virus from the air in a room where an infected person breathed/coughed/sneezed up to 3 hours before. This is similar to other contagious respiratory diseases, like flu (which can live in the air for 2-3 hours) and measles (which can live in the air for up to 2 hours).

That’s why it’s important to stay 6 feet away from other people – to prevent yourself from getting a respiratory droplet shower (yuck!).

If it is hard to stay 6 feet away from others, like when you’re in a grocery store or any other building, it is recommended that you wear a cloth face mask. This protects your nose and mouth from coming into contact with virus droplets in the air from the people around you or any virus hanging around in the air from people there before you. Check out this video from a study in the New England Journal of Medicine (NEJM) to see how much spray comes out of your mouth when you just talk.

It’s really important to remember that surgical masks and N95 respirators should not be worn by the general public – they are in short supply and should be reserved for healthcare workers.

That is why homemade fabric face masks are recommended for the general public. But which fabrics are best for making effective face masks (ones that will filter out small particles, like viruses but still let you breathe comfortably)? Each different type of fabric is woven to a different tightness, creating various “pore sizes” – the tighter the cloth is woven, the smaller the particles that can pass through.

Various household fabrics have been tested for their efficacy at filtering bacteria, viruses, and small particles (representing viruses). One study found that vacuum cleaner bags, tea towels, and a cotton mix most effectively filtered bacteria and viruses, behind surgical masks; however, vacuum cleaner bags are hard to breathe through, so they are not recommended to be used as face masks. Another study tested 30 materials on their breathability and ability to filter small particles (down to 0.3 microns, about the size of a smallpox virus particle – coronavirus is about 0.1 microns in size). The ‘Goldilocks’ materials (ones that filtered efficiently but still let the wearer breathe comfortably) were denim (10 oz), bed sheets (80-120 thread count), paper towels, canvas (0.4-0.5 mm thick), and shop towels.

Okay, back to how the virus invades your body. Contact with an infected person can transfer virus from them to you. An infected person may touch their nose or mouth, picking up some virus on their hands – the same hands they use to shake yours. Then you touch your nose or face – boom, you’ve infected yourself.

Virus-containing respiratory droplets can also land on other surfaces, such as doorknobs, handrails, tables, and any other surface you can touch. If you touch an infected surface then touch your face, nose, or eyes, you could indirectly infect yourself. This is why hand washing and sanitizing is so important – it removes any virus particles you may have picked up while touching infected surfaces.

Another possible way to be exposed to the virus is through fecal-oral transmission – going from an infected person’s poop into your mouth (ew!). If an infected person goes to the bathroom and doesn’t wash their hands, they can infect everything (and everyone) they touch. If you touch the infected item then touch your face, voila, you’ve infected yourself from someone else’s poop. Now, it’s important to note that, while researchers did find the virus in infected people’s poop, they don’t yet know if someone can get sick after being exposed to infected poop.

Questions have been raised about other possible transmission routes:

There are also many, many myths circulating about how coronavirus spreads or how to prevent getting sick. Lists of coronavirus myth busters can be found on the World Health Organization (WHO) and Healthline websites.

Who can spread coronavirus?

When you think of an ‘infected person,’ a visibly sick, coughing, sniffling person may come to mind. While the virus can definitely be spread by actively sick people, it can also be spread by people without any symptoms.

Someone may be infected and be totally unaware because they have no symptoms (called asymptomatic). Estimates of how many people with coronavirus who don’t have symptoms have ranged widely, from 17.9 percent to almost 50 percent (CDC director Dr. Robert Redfield estimated 25 percent and National Institute of Allergy and Infectious Disease (NIAID) director Dr. Anthony Fauci estimated 25-50 percent). Even though they aren’t sick, they can still spread the virus to others, who can become infected and get sick.

An infected person can also spread the virus before they start having symptoms and know they are sick (called presymptomatic). There is a lag time (called the incubation period) between when someone is infected with a virus and when they start showing symptoms. For coronavirus, the incubation period ranges from a few days to almost two weeks. As the virus replicates in their body, they can spread the virus a few days before symptoms appear.

What should I do?

Remember (as if you haven’t heard this enough already), to protect yourself and others from coronavirus:

  • Wash your hands for 20 seconds (or use alcohol-based hand sanitizer) often
  • Try not to touch your face (I know, it’s hard)
  • Cover your cough and sneeze (using your elbow is best)
  • Clean frequently touched surfaces often
  • Minimize person-to-person contact (stay at home as much as possible)
  • Practice social distancing by staying 6 feet away from other people

 

 

BioSpace source:

https://www.biospace.com/article/all-the-ways-we-know-that-you-can-get-coronavirus