Adults who can’t or don’t want to get the updated booster formula from Pfizer-BioNTech or Moderna can get a shot of Novavax as their booster, the US Centers for Disease Control and Prevention and the US Food and Drug Administration said last week.

The new authorization applies to people who’ve gone at least six months since their primary vaccine and who have’t had any booster yet. About 48% of US adults are fully vaccinated but haven’t yet received the first booster dose.

Novavax has been available to adults and teens as young as age 12 as the original or primary vaccine, but this is the first time some people will be able to get it as a booster. Like the first two doses of Novavax, its availability as a booster dose will give those who’ve been holding out for a protein-based or more “traditional” vaccine another option. Vaccine types like Novavax have been around for more than 30 years, according to the CDC, and used against shingles, the flu and more.

You can choose to get Novavax as a booster because you don’t want a different formula or have an allergy to other formulas, and it doesn’t matter which vaccine you originally received, as long as you haven’t had a booster yet. The FDA authorized a “mix and match“approach to boosters last year.

“It’s good to have a vaccine on board like Novavax because it’s another option for those that might have contraindications to the other vaccine platforms,” ​​Ross Kedl, a professor of immunology and microbiology at the University of Colorado Anschutz Medical Campus, said in an email in June. “Some have allergic reactions or more rare concerns like blood clots.” (The Johnson & Johnson COVID-19 vaccine is still authorized in the US, but its use has been limited because of a rare but serious risk of blood clots.)

Health officials broadened the use of Novavax as the push to get more people boosted and protected ahead of the holidays, and a likely-to-be harsh flu season, is in progress. While Novavax’s booster is the same as its original vaccine, Pfizer-BioNTech’s and Moderna’s updated vaccine formula target the more recent BA.5 variant of omicron, and have been available for a couple of months.

Novavax was a long time coming, but it’s had a rough start getting off the ground. The company had a contract with the federal government through Operation Warp Speed but experienced manufacturing problems that hindered a speedy emergency use authorization. It’s available in other countries, including Canada and Australia, under the name Nuvaxovid.

Here’s what to know about it as a primary vaccine as well as a booster.

Can I get a Novavax booster?

You can get a Novavax booster if you’re age 18 or older, you haven’t received any booster yet, and it’s been at least six months since your original vaccine. For people who got Pfizer’s, Moderna’s or Novavax’s vaccine, that means at least six months have passed since your second shot. For people who got Johnson & Johnson’s vaccine, that means at least six months have passed since your one dose.

People who’ve received two original shots and then a booster in 2021 or 2022, for example, aren’t eligible right now for an additional boost with Novavax. If Novavax develops a new vaccine formula, health officials could authorize it and open it up to a broader group.

When and where can I get a Novavax shot?

You should be able to see places that have Novavax in stock on the government’s vaccine finder website. To find a dose near you, select Novavax from the list and enter your ZIP code. You should find it under “Primary vaccines,” not “Updated vaccines,” since the updated vaccines refers to the new, targeted formula from Pfizer-BioNTech and Moderna.

Who can get Novavax’s primary vaccine?

Novavax’s COVID-19 vaccine is for people age 12 and older who haven’t received any COVID-19 vaccine yet. It’s authorized as a two-dose primary series, with each dose typically given three weeks apart. (But you can get the second dose up to eight weeks after the first, per the CDC.)

As is the case with any other drug or vaccine, people with allergies to an ingredients in Novavax shouldn’t take it, Kristen Nichols, pharmacist and senior content management consultant at Wolters Kluwer, said in an email.

What is Novavax? How is it different?

Novavax is a COVID-19 vaccine that uses a more traditional protein-based technology, unlike the other vaccines currently available in the US. Pfizer-BioNTech and Moderna use mRNA technology, and Johnson & Johnson is a viral-vector vaccine.

In the Novavax vaccine, a purified protein of the virus is mixed with what’s called an adjuvant — additives that “wake up the immune response and tell it to take this target seriously,” Kedl said.

Dr. Glenn Wortmann, an infectious disease specialist with MedStar Health, said the general approach of most vaccines is to use a protein base.

“Specifically, Novavax is very similar to the hepatitis B vaccine” that most of us receive as children, Wortmann said. Some vaccines for influenza, shingles and other ailments use a similar technology.

While it offers another option, however, the jury may be out on whether Novavax offers superior immunity to Pfizer’s and Moderna’s vaccines.

“Immunologically speaking, in my view it does not really bring an awful lot on its own to the table that is not already well-addressed by the mRNA vaccines,” Kedl said.

However, it is easier to store and ship than mRNA vaccines, he said. This may be an advantage when vaccinating harder-to-reach communities where keeping finicky vaccines cool in the fridge may be difficult. But Novavax has serious drawbacks when it comes to manufacturing, Kedl said, because it isn’t cheap for the company to produce and purify the proteins.

The “mRNA vaccines skip that step because they turn each individual into their own vaccine manufacturer,” he said. They work by teaching our cells to make the protein themselves that will trigger an immune response.

For this reason, mRNA vaccines are easier to adjust than Novavax when a new variant comes along, Kedl said.

“The mRNA platform is far more modifiable than what Novavax does,” he said. “Every time a new variant vaccine needs to be made, Novavax is going to have to do a lot of work in the lab to figure out which changes will still allow a good protein to be made and purified at mass quantities.”

How effective is Novavax?

Published results from a trial found that Novavax’s primary vaccine was more than 90% effective against symptomatic COVID-19, and 100% effective against severe disease and death. But importantly, that trial was conducted before the omicron or delta variants were widely circulating. Both the delta and omicron variants — including omicron subvariant BA.5 — are more contagious and evade some immunity from vaccines and prior infection.

Real-world data comparing the effectiveness of Novavax to other vaccines doesn’t exist yet. According to the World Health Organization“It is impossible to compare vaccines head to head due to the different approaches taken in designing the respective studies.”

Though it’s not entirely clear yet how effective Novavax will be in real time as a booster against the newer versions of COVID-19, the FDA concluded in its authorization that Novavax will have a benefit as a booster dose. But boosters, in general, have provided more protection to people as the virus continues to mutate and people lose immunity from earlier vaccinations or past infections with COVID-19. Older adults in their 60s and up, or people with underlying health conditions are at higher risk of severe disease and may especially benefit from a booster dose. A report published Oct. 7 by the US Department of Health and Human Services found that COVID-19 vaccines were linked to about 650,000 fewer hospitalizations and 300,000 fewer deaths in seniors and other people who are enrolled in Medicare in 2021.

What are the side effects of Novavax?

Like with other vaccines, side effects after getting the Novavax vaccine are typically mild, common and happen within seven days of getting the shot, according to the CDC. Examples are tiredness, fever, chills and a headache, which clear up within a couple of days. These are signs your immune system is reacting and mounting a defense.

Myocarditis and pericarditis (inflammation of the heart) are rare side effects of Novavax. Six out of roughly 40,000 vaccine recipients developed heart inflammation in a clinical trial with Novavax, compared with one in the placebo group. Younger men or teen boys have been at higher risk of developing myocarditis or pericarditis after vaccination with an mRNA vaccine, typically after the 2nd dose. Most who developed heart inflammation felt better quickly.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.