Will the COVID-19 Booster Protect Me Against Variants?

Medically Reviewed by Melinda Ratini, DO, MS on February 25, 2022

Viruses change all the time. It’s how they survive. They get a chance to mutate every time someone gets sick and passes those germs to someone else. This process can spawn a new version of a disease called a variant.

The CDC keeps track of coronavirus variants that pop up in the U.S. and around the world. And experts expect them to keep coming as long as COVID-19 sticks around. But viruses can’t change as much when we don’t give them a chance to spread.

You help stop future variants from forming when you get vaccinated. The CDC considers you optimally protected when you’ve got all your recommended booster shots.

Here’s more about vaccines and variants.

Are Variants Expected?

Yes. Variants aren’t a surprise. They’re common in other viruses, including influenza. That’s why you need to get a flu vaccine every year. Scientists assume we’ll see more coronavirus variants in the future. But we might not need to worry about all of them.

There are different classes of coronavirus variants, which include:

A variant being monitored is a concern but isn’t a current threat to public health.

A variant of interest is a form of the virus that scientists think might be more contagious, harder to test for, or more likely to cause serious illness.

A variant of concern is a version that scientists know is worrisome. It’s a variant with real-world evidence that shows it can do one or more of the following:

  • Spread easier
  • Cause more breakthrough infections or reinfections
  • Avoid testing
  • Cause more severe illness
  • Be harder to treat or vaccinate against

So far, the two COVID-19 variants of concern include:

  • Delta (B.1.617.2)
  • Omicron (B.1.1.529)

In August 2021, Delta became the dominant variant for a while. It was a lot more contagious than previous versions of the coronavirus, and it made people a lot sicker. All FDA-authorized monoclonal antibody treatments can treat this version of COVID-19.

In early 2022, Omicron caused a dramatic spike in cases in the U.S. So far, it’s the most contagious version of COVID-19. But it doesn’t seem to make people as sick as other variants. Certain kinds of COVID-19 treatments don’t work as well on this variant.

A variant of high consequence is one that vaccines don’t protect you against. Right now, there aren’t any of these kinds of variants for the coronavirus.

Do Boosters Protect Against Variants?

No vaccine is 100% effective. But all three FDA-authorized vaccines greatly lower your odds of serious illness and death from COVID-19. That goes for people who are either fully vaccinated or have the booster.  

Vaccines lose their strength over time. Booster shots give you added protection by restoring your defense against COVID-19. The CDC and FDA both recommend that everyone ages 12 or older get a booster. They prefer you get an mRNA vaccine made by Pfizer or Moderna, if possible.

Most people who get COVID-19 are unvaccinated. But it’s important to note that you can still catch and spread the coronavirus if you’re fully vaccinated or optimally protected. These are called breakthrough infections. They tend to be mild, but they were more common during the Omicron surge compared to Delta.

Compared to unvaccinated or fully vaccinated people, those with an additional dose or booster shot are:

  • Least likely to test positive for COVID-19
  • Least likely to die from the virus

People ages 65 and older see the most benefit from these extra vaccines.

Can Boosters Protect Against Future Variants?

Current vaccines work well at preventing serious illness from all coronavirus variants. Experts expect that success to continue. But there’s no way to know how well vaccines will protect you against variants that don’t exist yet.

The CDC keeps a close eye on how effective COVID-19 vaccines are in the real world. They’ll know if a new variant of concern arises. Some major things they track are rates of:

  • Infection
  • Symptomatic illness
  • Hospitalization
  • Death

They also look to see how well vaccines protect:

  • Different age groups
  • People with other health conditions
  • People who got vaccine boosters

The CDC can make changes to protect the public if they notice a big drop in how well vaccines work. They might suggest more booster shots or additional doses in the future. Scientists might also change COVID-19 vaccines to target certain variants.

But so far, no version of the coronavirus is completely resistant to vaccines.

There’s evidence that current vaccines might not prevent asymptomatic or mild infections from all coronavirus variants. But they still give you strong protection against serious illness, hospitalization, and death.

Protect Yourself and Others

It’s safer for you to go about your daily life when you’re up to date on your vaccines. But it’s still important to take preventive steps if COVID-19 transmission is high where you live.

Health measures that can slow the spread of the coronavirus include:

  • Wear a mask.
  • Physically distance.
  • Wash your hands.
  • Limit big gatherings.
  • Avoid crowded indoor areas.

Keep the vaccine conversation going with your doctor. They’ll let you know if you’ll need additional doses or boosters in the future.

Show Sources



Yale Medicine: “Virus Variants: What Do You Need to Know Now?” “COVID-19 Boosters: The Latest Advice.”

CDC: “Myths & Facts,” “About Variants,” “SARS-CoV-2 Variant Classifications and Definitions,” “COVID Data Tracker,” “Vaccines & Immunizations – Interim Clinical Considerations,” “How and Why CDC Measures Vaccine Effectiveness,” “Protect Yourself.”

Johns Hopkins Medicine: “COVID Variants: What You Should Know.”

University of Maryland Medical System: “COVID Variants and the Vaccine.”

JAMA: “Association Between 3 Doses of mRNA COVID-19 Vaccine and Symptomatic Infection Caused by the SARS-CoV-2 Omicron and Delta Variants.”

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