Is the Novavax COVID vaccine better than the mRNA vaccine?What we know so far

As newer coronavirus vaccines roll out across the country, yet another competitor has joined the ranks. In early October, the U.S. Food and Drug Administration approved a new booster shot made by Novavax. Like the mRNA-based Pfizer and Moderna vaccines, it targets the SARS-CoV-2 variant XBB.1.5, a descendant of Omicron. It’s the first protein vaccine to emerge in more than a year, and some public health experts say it’s encouraging news for people hesitant about the mRNA vaccines that have been widely used throughout the pandemic.

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scientific american Experts were consulted on the latest science behind the new lenses.

How is Novavax’s vaccine different?

Moderna and Pfizer’s mRNA vaccines contain modified viral genetic material that the body’s own cellular machinery uses to make viral proteins that trigger an immune response, while Novavax relies on a more traditional approach, injecting shots similar to SARS-CoV Protein in -2. directly into the body. This protein-based approach has been used for more than 30 years in other vaccines, such as the hepatitis B vaccine. Novavax produces the protein in moth cells, which grow faster than mammalian cells.

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The Novavax vaccine also contains a proprietary compound called Matrix-M, which was developed from the bark of the Chilean soap tree to further stimulate the immune system. Matrix-M is currently being incorporated into other vaccines, including a malaria vaccine approved by the World Health Organization earlier this month.

Which variants does it target?

The new Novavax vaccine was developed to target the XBB.1.5 variant of the virus, which also targets newer vaccines from Moderna and Pfizer. None of these viruses are optimized against new versions of the virus, including the Eris and Pirola variants that became prominent in August and appear to be better able to evade the immune system than previous variants. (The FDA selected the XBB.1.5 variant in June as a booster for this fall). This is nothing new, said Gregory Poland, a vaccinologist at the Mayo Clinic who said vaccine companies have been “playing catch-up” with emerging variants throughout the pandemic.

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All three vaccine boosters appear to provide at least some protection against the new variants. But one drawback of protein vaccines is that it takes researchers longer to develop new formulations to protect against new variants, whereas mRNA vaccines can be tweaked more easily.

How’s the effect?

Kirsten Lyke, an infectious disease researcher at the University of Maryland, said Novavax’s efficacy is about the same as other coronavirus vaccines. A study published this month found that a Novavax booster dose was about 55% effective at preventing COVID-19 symptoms and 31% effective at preventing infection, similar to the mRNA vaccine.

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Lake’s July research report published in the magazine npj vaccine tested whether “mixing and matching” different coronavirus vaccine and booster types could produce stronger or longer-lasting immunity against the virus. The study found that regardless of whether a person initially received the mRNA or protein vaccine, all boosters produced similar antibody responses. Other evidence published in 2022 suggests that receiving an mRNA booster vaccine after a protein vaccine, such as Novavax’s original vaccine or the now-discontinued Johnson & Johnson protein subunit vaccine, may result in the best immunity.

The antibodies produced by the new Novavax booster may last slightly longer than those produced by the mRNA vaccine, according to Lyke’s latest research. But Lyke says that’s not yet conclusive: By the time the study began in early 2022, many of the vaccinated people had recently been infected with Omicron or another dominant variant that evades the immune system. The infection caused their bodies to develop a level of natural immunity that was difficult to distinguish from the effects of the vaccine.

Lake said it’s nearly impossible to directly compare the efficacy of different vaccines, given that people have different combinations of exposures, infections and vaccines. “I just don’t think we can do these trials anymore,” she said.

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What are the side effects?

The risk of myocarditis or pericarditis (an occasional heart attack, especially in younger men) appears to be lower with the Novavax booster than with the mRNA vaccine, although it is not zero risk. It also has fewer side effects, including muscle fatigue and nausea, within 48 hours of vaccination. “If people had side effects from the mRNA vaccine, I would recommend trying the protein subunit (vaccine),” Poland said. “Our goal is to protect you.”

But it’s difficult to draw firm conclusions about the vaccines’ relative safety. “We have millions of data points for the mRNA vaccines, but we don’t have data for Novavax,” Poland said. Because of manufacturing issues, the company’s vaccine against the original coronavirus variant wasn’t approved until 2022, by which time most people who wanted a vaccine had already received it. The CDC estimates fewer than 90,000 doses of the original Novavax vaccine have been administered, and only a few hundred people have received boosters in clinical trials.

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When will Novavax be available for fall and winter?

Novavax said the booster shot is now available in pharmacies and has shipped millions of doses to thousands of locations across the country. Like the mRNA vaccine, the Novavax booster is one dose, but the CDC recommends that unvaccinated people receive two doses eight weeks apart.

Despite rising coronavirus infections in recent weeks, the rollout of the latest round of boosters, including both mRNA and protein varieties, has lagged. This is largely because people are confused about how to pay for the vaccine after the U.S. government announced it would no longer pay for all COVID-19 vaccines and required all insurance companies to cover them for free. As states continue to grapple with insurance and birth complications, boosters will not be available immediately in some areas. But Lake said no matter which vaccine booster is rolled out first, the most important thing is to “pick one and get it.”