Against a pale orange background, there is an illustration of two dark orange waves covered in black illustrations of coronavirus. A person with light brown skin and dark brown skin runs from the waves with their arms out. They wear dark gray pants, a light gray cardigan, and a white shirt.
Illustration: PGN

COVID-19-related deaths continue to rise as new variants and subvariants evade our immune systems’ defenses. These variants and subvariants emerge during the viral replication process, when a virus enters a body, attaches to a host cell, and makes a copy of itself. Variants and subvariants behave differently than previous versions of SARS-CoV-2, the virus that causes COVID-19.

What is the difference between a variant and subvariant, how are they different from viral strains, and how can we protect ourselves from these “fitter” viruses? Read on to learn more.

How do viruses mutate?

Exposure to SARS-CoV-2 causes the virus to enter the body through your mouth, nose, or eyes, where it multiplies inside your healthy cells, causing a COVID-19 infection. As the virus replicates, frequent errors occur, resulting in copies of the virus’s genetic code that differ from the original virus. 

That genetic code is called ribonucleic acid (RNA), and these differing copies of RNA are called mutations. A virus with mutations in its RNA can become a new variant, subvariant, or strain.

What is a variant?

A variant is a version of a virus that contains one or more mutations in its RNA. These mutations can change the virus’s behavior, making the virus better at evading our immune responses from previous infection or vaccination, which allows the virus to spread more easily. 

This is why scientists have been reformulating COVID-19 vaccines to target new variants. Examples of COVID-19 variants include Delta, which became the dominant COVID-19 variant in 2021, and Omicron, the dominant variant right now.

What is a subvariant?

When a variant develops slight genetic mutations of its own during replication, it becomes a subvariant. One example of an Omicron subvariant is BA.5, which developed a spike protein—a molecule on the virus’s surface—that was different from previous Omicron subvariants. BA.5’s spike protein allows it to attach to cells more easily, which makes it more transmissible than other Omicron subvariants.

The updated COVID-19 vaccine, which is available now and recommended for everyone 6 months and older, targets the Omicron subvariant XBB.1.5 and offers protection against newer variants, like BA.2.86.

What is a strain?

Colloquially, “variant” and “strain” are often used interchangeably to refer to mutated forms of a virus, but they’re technically different. A strain is a version of a virus that has undergone significant genetic changes that drastically change its behavior. 

SARS-CoV-2 is a strain of coronavirus, a large family of viruses that typically cause mild to moderate upper respiratory tract illnesses in humans. SARS-CoV-2 is different from other coronaviruses because its associated symptoms can be much more severe, leading to higher rates of hospitalization and death.

How can we protect ourselves from new COVID-19 variants and subvariants?

Every time we get infected with COVID-19, we give the virus a new opportunity to mutate. Applying layers of protection—like getting vaccinated, wearing masks, and improving indoor ventilation—will give COVID-19 fewer chances to produce new variants.

Staying up to date on COVID-19 vaccines is a safer and more reliable way to build protection against COVID-19 than getting sick from it, the CDC says. Vaccination can also reduce the severity of a COVID-19 infection if you contract the virus and reduce your risk of developing long COVID. Talk to your health care provider about the updated COVID-19 vaccine and visit to find pharmacies offering it near you.

Wearing a high-quality mask correctly can provide an additional layer of protection from COVID-19 variants and subvariants. Learn more about the different types of masks and how they work from the CDC.