Just like the flu, COVID-19 continues to evolve every year with new and smarter variants

Having new COVID-19 variants emerge throughout the year is now par for the course. Like with influenza (the flu), the SARS-CoV-2 virus that causes COVID-19 continues to evolve every year as it tries its best to infect as many hosts as possible and survive our immune systems’ defenses. In fact, the spike protein itself, which allows the virus to attach to our human cells, has undergone more than 111,200 mutations alone since 2019.

Pathologists Hannah Wang, MD, and Daniel Rhoads, MD, explain what this means for the future of COVID-19 vaccination and why we should be just as concerned about up-and-coming COVID-19 variants as we’ve been in the past.

Why are there so many COVID-19 variants?

One of the most recent COVID-19 variants is the XEC variant. This variant is a recombinant variant, meaning it’s a combination of two older variants within the JN.1 parent lineage. The JN.1 variants were dominant in the U.S. during the winter of 2023 and early spring of 2024. These belong to the omicron family of COVID-19 variants that now make up nearly all cases of COVID-19 in the U.S.

And the buck won’t stop there. Even the JN.1 variants have evolved into different subvariants, informally called FLiRT and FLuQE, that have their own unique set of mutations on top of all the other mutations of every variant that came before them.

“If you look back to the end of 2019 and the beginning of 2020, we were seeing variants that were very different from one another. You can think of them as different families of variants showing up,” says Dr. Wang. “Now, since late 2022 and early 2023, omicron has become the overarching variant family. Over the past few years, we've seen more new variants come up, but they're all within this one family.”

That means the latest COVID-19 variants are more closely related to one another with only slight differences in their genetic code.

“Let’s use cars as an analogy. SARS-CoV-2 is like the car maker, and the variant is like the model of a car,” illustrates Dr. Rhoads. “Every few years, the manufacturer redesigns the model. The new one looks substantially different than last year’s model, and although it definitely is substantially different, it is still pretty similar. Omicron is like that new redesigned model, and SARS-CoV-2 keeps coming out with new trim packages for omicron.”

Still, even one small change can affect the way a virus looks, functions and infects its hosts.

Take, for example, KP.2. The U.S. Centers for Disease Control and Prevention (CDC) designed their fall 2024 vaccine to target KP.2 and its specific mutations because it was gearing up to be the most infectious, dominant variant at the time.

“It’s going to be a little less recognizable by our immune system. That’s why KP.2 sort of took off earlier this year. And it’s also why the public health authorities in the U.S. have directed vaccine manufacturers to target one of the subvariants within the FLiRT variant — KP.2 — for vaccine manufacturing,” explains Dr. Wang.

Does the vaccine protect against current COVID-19 variants?

Even though it wasn’t long before KP.3.1.1 emerged as the most dominant COVID-19 variant after the KP.2 vaccines were produced, the COVID-19 vaccine still offers protection.

“It’s slightly different from the KP.2 that the vaccines are targeting but they’re still in the same family,” clarifies Dr. Wang, “So, we expect the COVID-19 vaccine will still provide a good amount of protection until a new one comes out next year to target new COVID-19 variants.”

While it’s possible to get reinfected, the number of cases that result in serious illnesses, hospitalizations or death is relatively low because vaccines are working to suppress the strength and spread of COVID-19. There are also new treatments for COVID-19, making the recovery process even more manageable.

“Staying away from others who are sick, staying away from others when you are sick and staying up to date on vaccines are the best tools we have for preventing respiratory virus infections like COVID, influenza and RSV,” states Dr. Rhoads.

How many COVID-19 variants are there?

Although the original virus is no longer circulating, dozens of variants and subvariants continue to circulate around the world.

In the U.S. alone, the CDC continues to monitor dozens of variants currently abounding in the U.S., including up-and-coming variants of interest. Some of the most prominent COVID-19 variants that have been tracked as part of this process include delta, omicron and a variety of once-dominant subvariants, including:

  • HV.1
  • EG.5
  • FL.1.5.1
  • XBB.1.5
  • BA.2

"SARS-CoV-2 has demonstrated continual evolution since its emergence in humans. This evolution results in new variants that emerge and replace existing variants over time,” notes Dr. Rhoads. “Since the emergence of omicron in 2021, these variants have shared similar disease symptoms and severity over time.”

Do COVID-19 variants share the same symptoms?

You can think of current and emerging COVID-19 variants like brothers, children, grandchildren or first cousins all within the omicron family. They’re so closely related that they share a lot of the same features while also having very unique mutations that set them apart from all other COVID-19 variants. That means your symptoms will likely remain the same regardless of which COVID-19 variant you come in contact with.

“The symptoms are generally the same or similar, but the caveat is that the symptoms can look different in any one individual,” states Dr. Rhoads.

That means COVID-19 affects everyone differently. You can be asymptomatic or have any number of symptoms that include:

What can you do to minimize infection from new COVID-19 variants?

You want to follow the same guidelines for new COVID-19 variants that you’ve followed for every other variant and subvariant of the coronavirus.

The best preventive measures include:

“Although COVID-19 may feel like old news, it’s still one of the most important and common causes of respiratory illness in our local and global communities today,” emphasizes Dr. Wang. “Scientists, healthcare providers and public health officials are still hard at work studying and battling COVID-19 as it continues to evolve. Help them by taking care of yourselves and your loved ones.”