The Biology of Coronavirus Preventative Measures

Editor’s note: Because researchers around the world continue to study this virus, the information here may be outdated in a few weeks. If we’ve made corrections, we’ll let you know up here.

“Every virus is unique, and the virus that causes COVID-19 is very different than your standard cold-causing coronavirus, and it’s different than the flu,” says Dr. Matthias Schnell, director of the Jefferson Vaccine Center. “Some of our protective measures come from our knowledge of how viruses work in general, and some come from our still-developing understanding of what makes this virus unique.”

Dr. Schnell, whose lab works to develop vaccines for emerging disease like Ebola and MERS, recently shifted gears to develop a vaccine candidate for SARS-CoV2, the coronavirus that causes COVID-19.

Here we tap Dr. Schnell’s knowledge of viruses to understand some of the advice we’ve been getting about the coronavirus.

Why does something as simple as washing hands help against something so deadly?

Coronaviruses have a weakness that we can use to our advantage to prevent spread. They are covered in a rather fragile lipid bilayer, a sort of thin film of grease. When you drop soap on a film of grease in a pan, that grease separates. It’s the same idea with the layer of lipids covering this virus particle, except in the case of a virus, the film is so tiny that it can’t be seen by standard microscopes. By rubbing soap on your hands into a good lather, you help break this nano-scale lipid viral covering.

What about hand sanitizers, do they really work? 

Hand sanitizers are effective against bacteria, but also have been tested to kill some, but not all viruses. We do know that they effectively destroy the coronavirus that causes COVID-19. It works a little differently than soap. Rather than breaking open the lipid bilayer, the alcohol mixed with a little bit of water (the small amount of water in sanitizer is important) destroys the virus by crumpling the surface proteins it uses to enter and infect cells. It’s like the sanitizer crushes the set of lock-picks that the coronavirus uses to break into our cells and infect them.

What’s the right way to use hand sanitizers?

You don’t need hand sanitizer when you’re at home. Soap works well and can be less harsh on your skin. But when you’re outside, getting groceries or other essentials – that’s when you get your hand sanitizer out.

A good rule of thumb is “sanitize in, sanitize out.” Sanitize before you enter a shared space to protect others from the virus that you might be carrying, especially before you pull that door handle. Pick up what you need, making sure not to touch your face. Then, sanitize again once you’re outside to get any germs you may have picked up in that shared space to protect yourself. Now that your hands are clean, it’s OK to scratch your nose.

Why are measures like 6-feet of space, quarantine and social distancing important?

The virus that causes COVID-19 is primarily spread via droplets rather than by air. While droplets can still spread through the air when someone sneezes or coughs, the droplets only stay in the air for a few hours. On the other hand, the virus can be infectious for up to 72 hours on plastic and stainless steel (think door handles or subway poles), according to new experiments that tested how long the virus remained infectious in different conditions and surfaces in a study published in the New England Journal of Medicine last week.

The quarantine measures that feel a bit like a lock-down, are actually extremely important in controlling the spread of the virus, which is quite infectious and can spread before symptoms appear. The 6-foot rule is just an easy way to help remember that closer contact increases your chances of either spreading or getting the virus.

We now know that the asymptomatic people – those showing little or no signs of infection – may be responsible for up to 80 percent of infections, some of whom will have serious and life-threatening complications.

If the flu and the cold are also viruses, why are we so worried about this virus? Isn’t the COVID-19 virus related to the virus that causes the common cold?

Yes, COVID-19 does belong to the same family as some of the common cold viruses. But this virus isn’t the common cold or even the flu. Viruses each contain a genetic code, instructions for building the proteins that make up the shape of the virus and the shape of the lock-pick the virus uses to break into and infect cells. The problem with the new coronavirus is that it is new to our immune system and there is no immunity in the population. In addition, the new coronavirus can cause more serious disease compared to other viruses. It’s the reason everyone is taking this virus so seriously.

Why is this new virus from animals infecting people?

Every time a virus divides inside our cells, their genetic code may slightly change. Those slight changes in code can also translate into slight changes in the shape of the lock-pick. And if the lock-pick changes, it also changes how the virus enters cells, and more importantly, which cells it enters and which species it can enter.

By our bad luck, the genetic code of the virus that causes COVID-19 has a lock-pick shaped perfectly for a lock or protein on human cells called ACE2. Unfortunately, humans have ACE2 on many cells, such as the cells that line the lungs, blood vessels, kidney and intestine. Unlike the common cold or flu, this coronavirus has additional tools in its lock-pick set that allows it to unlock and enter cells with ACE2 more easily and quickly, making it more dangerous. This is probably also why older adults are at greater risk for complications. If the virus is infecting organs of people whose organs are already stressed and busy fighting pre-existing conditions like heart disease, hypertension or lung disease, they are more likely to have difficulty fighting the disease.