Another highly contagious COVID-19 variant called XBB.1.5 has made its way to the U.S. with the World Health Organization (WHO) calling it “the most transmissible” variant to date.

Coined “Kraken” by a Canadian biology professor, the new variant is laying down roots in the U.S, although the U.S. Centers for Disease Control and Prevention (CDC) have had some wavering data on how many cases "Kraken" has caused. It now estimates that the variant will make up over a fourth of total cases this week.

“That doesn't mean the variant will cause more or less severe disease than previous versions of COVID,” says Dr. Charles Miramonti, a senior medical director at Oak Street Health in Indianapolis, Indiana. “But it does spread more effectively than previous strains.”

As talk of a winter surge looms, you may be wondering about your level of immunity and if you can evade infection by yet another strain. Now that it’s been over two years since the authorization of the first COVID-19 vaccines, followed by booster rollouts, you may be confused about how many COVID shots there are out there, and whether you are protected.

How many COVID shots have there been?

Health officials have recommended four shots to most people, Miramonti says.

Four types of COVID-19 vaccines have been made available in the U.S: Pfizer-BioNTech, Moderna, Novavax, and Johnson & Johnson. Johnson & Johnson's is a single-dose vaccine, but all others are a two-dose regimen. These doses are part of the primary, or initial, series of vaccines against the virus.

Due to immunity waning over time, booster shots became available to keep people continuously protected. Pfizer and Moderna offered a booster to their m-RNA vaccines in the fall of 2021. In the fall of 2022, they also offered a bivalent booster, which specifically targets the Omicron sub-variants that have dominated the country.

Johnson & Johnson's original dose has since been limited to people who clinically cannot get the Pfizer or Moderna vaccine or for those who would otherwise forgo vaccination. If you had their single-dose vaccine, you were eligible for both boosters from Pfizer or Moderna.

Novavax, which was authorized for use in the U.S. much later than the others and isn't as commonly used, has a booster. While it's not an updated bivalent booster, it's thought to potentially offer broader protection. Its manufacturer says its original formula offers protection against several COVID strains, including Omicron BA.5, according to Yale Medicine.

If you’re older and/or moderately or severely immunocompromised, you may have received up to two additional "booster" doses of the original vaccine, in addition to a dose of the updated Omicron vaccine this fall. People over 50 have also been eligible for an additional booster as of spring 2022.

These are the three most common COVID vaccines and the number of shots associated with them

The two-dose Moderna Vaccine

• 4 shots: two shots for the primary dose, one booster which became available in the fall of 2021, and the new bivalent booster available as of September 2022

• Some people may have 5 shots if they are over 50 or immunocompromised

The two-dose Pfizer Vaccine

• 4 shots: two shots for the primary dose, one booster which became in the fall of 2021, and the new bivalent booster available as of September 2022

• Some people may have 5 shots if they are over 50 or immunocompromised

The one-dose Johnson & Johnson vaccine

• 3 shots: one shot for the primary dose, and two boosters from Moderna or Pfizer when they became authorized in the Fall of 2021, and then in 2022 respectively. The CDC says mixing and matching works fine for people in this category.

• Some people may have 4 shots if they are over 50 or immunocompromised

There are some nuances to how many vaccines and boosters are generally available. Some people with weakened immune systems qualify for an additional dose, which works to “improve immunocompromised people’s response to their initial vaccine series,” according to Johns Hopkins Medicine.

Do the boosters help against new variants?

Experts explain that while new variants can be immune-evasive, getting vaccinated and boosted is the best way to stay protected from infection and getting severely ill. It's still early to say with certainty how well the vaccine will work against "Kraken," derived from Omicron, but experts believe it will likely be generally as effective as other variants.

It is not too late to get the bivalent booster, which will be the most effective booster against the current strains from getting severely sick, says Dr. Preeti Malani, an infectious disease specialist at the University of Michigan.

“The name of the game is to not get hospitalized if you’re vulnerable,” she says.

For those who want a bivalent booster, you must be at least two months past your primary series. If you have recently had COVID and want to get the bivalent booster, consider delaying your appointment by three months from the onset of symptoms or a positive test.

The more a variant circulates in a community, the more it can mutate and evade immunity from both vaccination and prior infection. Since getting vaccinated can help reduce the spread of the virus, getting as many people as possible vaccinated in a community minimizes the chance of new variants developing.

“Updated COVID-19 boosters can help restore protection that has decreased since previous vaccination,” the CDC says.

Do you need another COVID booster?

There is not a new booster that is targeting "Kraken" as of now. Experts instead point to the low rates of vaccination and booster vaccination for the already available ones.

The vast majority of children have not been vaccinated at all, per data from November from the CDC. In a survey from Morning Consult conducted in November, nearly half of U.S. adults who are vaccinated and did not receive a booster from September to November said they do not plan to get the bivalent one, many people citing that they don’t have time to get one or don’t see the point.

As the variants change, vaccine fatigue and, now, booster fatigue, has set in, but remaining up-to-date on vaccines and boosters that are authorized can help you do your part in limiting the spread.

“The newest boosters are still saving lives and keeping people out of the hospital,” Miramonti says. “They’re keeping secondary infections to a minimum,” adding they protect people against longer-term complications from COVID that can weaken the immune system.

This story was originally featured on Fortune.com

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