Science

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

A question you may be wondering: Is coronavirus worse than the flu?

You already know a new virus has brought normal life to a halt in the United States. But you may not remember what a virus even is.

They're invisible and can make us sick — but how? And why is it so hard for scientists to stop a new virus?

There are many different types of viruses, including ones that affect animals, plants and other organisms, so it's often a challenge to nail down an answer to even simple questions.

The answers below won't explain how every virus behaves, but in a time where it's easy to feel powerless and confused, they will help you understand why fighting the current pandemic is such a challenge.

What is a virus?

A virus is a microscopic piece of genetic material surrounded by a coat made of proteins. It enters healthy cells and hijacks them, creating copies of itself.

When viruses begin replicating inside a living organism, it can cause an infectious disease. In the case of the current coronavirus pandemic, the virus is SARS-CoV-2 and the disease is called COVID-19.

Are viruses alive?

It's complicated.

The National Human Genome Research Institute describes viruses as existing "near the boundary between the living and the nonliving."

That's because viruses can't function without interacting with a living cell. On their own, they're also essentially inert — unable to move — as a 2017 study notes.

“By themselves, they can’t do anything. They need a host cell to replicate,” virologist Paulo Verardi told USA TODAY. Verardi works on vaccine development and is a University of Connecticut professor.

He suggested thinking of them like a parasite: An organism that survives by harming another species.

But definitively answering whether a virus is alive may be more of a philosophy question than one strictly for science, Verardi said.

How do you kill a virus?

If it's outside your body, soap. Once the virus begins replicating inside your body, it's much harder.

Most viruses, especially respiratory viruses, are easily "disassembled" by soap when they are outside your body, Verardi said.

As long as you scrub your hands vigorously and rinse well with water, the soap essentially kills the virus.

Once the virus begins to take hold in your body, it's up to your immune system to clear it out.

There's two main ways this is done, Verardi said. First, the body can attempt to attack the virus directly, stopping it from hijacking cells and spreading rapidly.

And secondly, the body can attempt to spot its own cells that are infected with the virus and kill those cells. That's obviously not ideal and can cause damage to your body — but it's often necessary to stop the spread of the virus.

How and why does a virus make us sick?

The specifics of this will vary based on the virus. But broadly, Verardi says you should think of the interaction between the virus and your body as a war.

As a virus replicates in your body, two damaging processes are at play.

The first one: The virus is infecting cells and using them to replicate itself — this process often kills the infected body cells, causing damage to the body.

At the same time, the immune system is trying to clear the virus from the body. If too many cells are infected, the immune system's response — targeting infected cells — can also be harmful.

This battle can cause all sorts of problems in our body, depending on the virus and its location: inflammation, fever, mucus and more can occur.

In many cases, our bodies win the battle — viruses like the flu or the common cold are usually fairly easy for a healthy person to recover from.

But some viruses can be much harder to fight, especially for people with compromised immune systems.

Can vaccines or medicines help fight a viral disease?

Yes, but typically only when they target a virus specifically.

It's something like the relationship between a key and a lock: You can't use any key to get the desired result.

What makes things worse: As viruses replicate rapidly, some of them mutate. When that happens, vaccines and treatments must account for a virus that doesn't stay the same.

That's the case for the flu and why there is a new flu shot every year, Verardi said.

Drugs, specifically anti-viral medications, can help fight viruses once a person is infected. But they work best before a virus hijacks too many of the body's cells. Again, the same mutation dilemma often applies.

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

A line of shoppers snakes around a Costco store in Novato, California on March 14, 2020. Hoards of shoppers rushed to stock up on toilet paper, paper towels and cleaning supplies as communities begin hunkering down as a result of the Coronavirus. Josh Edelson, AFP via Getty Images

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Barricades are set up to prevent people from cutting in line as customers wait to enter a Costco store on March 14, 2020 in Novato, California. Justin Sullivan, Getty Images

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

A woman shops among empty shelves at a Hy-Vee food store Friday, March 13, 2020, in Overland Park, Kan. Charlie Riedel, AP

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

A customer carries a package of toilet paper at a Costco store on March 14, 2020 in Novato, California. Justin Sullivan, Getty Images

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Customers at grocery chain HEB in Austin, Texas shop for products on March 13,, 2020 as the city responds to concerns of the spread of the new coronavirus and COVID-19. James Gregg, Austin American-Statesman via USA TODAY NETWORK

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Rick Johnson picks up a package of toilet paper which was in short supply on the shelves Friday morning, March 13, 2020 around 10:30 a.m. at MillerÕs Hawkins Market in Ashland, Ohio. Tom E. Puskar, Ashland Times-Gazette via USA TODAY NETWORK

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Customers at grocery chain HEB in Austin, Texas look for products among increasingly empty shelves on March 13, 2020 as the city responds to concerns of the spread of the new coronavirus and COVID-19. James Gregg, Austin American-Statesman via USA TODAY NETWORK

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Check-out lines are long at Shop-Rite in Thornwood, NY on March 13, 2020. John Meore/The Journal News

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Panic shopping has caused traffic jams to enter the parking lot and long lines to enter the Costco in Teterboro, N.J. on Friday March 13, 2020. Tariq Zehawi, NorthJersey.com

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Costco contract employee from CDS wipes down and disinfect freezer doors on Thursday Morning March 12, 2020 in Austin, Texas. RICARDO B. BRAZZIELL , Austin American-Statesman via USA TODAY NETWORK

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Shoppers wait in an unusual long line at Costco on March 12, 2020 to stock up on last minute disinfectant items and food in Austin, Texas. RICARDO B. BRAZZIELL , Austin American-Statesman via USA TODAY NETWORK

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Empty shelves at Shop-Rite in in Thornwood, NY on Friday, March 13, 2020. John Meore/The Journal News

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Customers at grocery chain HEB in Austin look for products among increasingly empty shelves on March 13, 2020 in Austin, Texas. Bronte Wittpenn, Austin American-Statesman via USA TODAY NETWORK

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Shelves of alcoholic drinks were bare at a Walmart in Snellville, Georgia on March 13, 2020. Courtesy Samantha Griffin

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

A single package is left on an entire aisle dedicated to toilet paper that is completely empty in a local market amid the threat of coronavirus in Austin, Texas on March 11, 2020. Lola Gomez, Austin American-Statesman via USA TODAY NETWORK

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

A sign is seen limiting purchase amounts of bleach due to high demand at a Publix Supermarket amid concern over the COVID-19 virus on March 9, 2020, in Pembroke Pines, Fla. Brynn Anderson, AP

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Meat shelves lay empty at a supermarket in Saugus, Massachusetts on March 13, 2020. Supermarkets and shops around Boston have been emptied by customers in fear of Covid-19. JOSEPH PREZIOSO, AFP via Getty Images

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

People wait in line to enter a Costco Wholesale store before it opened in the morning on March 12, 2020 in Glendale, Calif. Once the store opened, the line moved smoothly and most people were able to enter to make purchases within about 15 minutes. Some Americans are stocking up on food, toilet paper, water and other items the day after the World Health Organization (WHO) declared Coronavirus (COVID-19) a pandemic. Mario Tama, Getty Images

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Water shelves lay empty at a supermarket in Saugus, Mass. on March 13, 2020. Supermarkets and shops around Boston have been emptied by customers in fear of Covid-19.1PV3IO JOSEPH PREZIOSO, AFP via Getty Images

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

Shoppers wait in a line stretching outside of a Trader Joe's supermarket, March 12, 2020, in the Brooklyn borough of New York. John Minchillo, AP

A coronavirus pandemic is sweeping the world, but what exactly is a virus? Is it alive?

A shopper looks at empty shelves of frozen food in a downtown supermarket on March 11, 2020 in Washington, DC. ERIC BARADAT, AFP via Getty Images