A Key Ingredient For Making A COVID-19 Vaccine Work : Shots - Health News Adjuvants play a crucial role in many vaccines' effectiveness. Some scientists say there needs to be more research into developing a wider variety of adjuvants because of how important they are.

The Special Sauce That Makes Some Vaccines Work

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All right. A closer look now at the research behind the race for a vaccine. For a COVID-19 vaccine to work, it has to get our immune systems to recognize the coronavirus. And to do that, many vaccines need what is called an adjuvant. As NPR science correspondent Joe Palca explains, getting the right adjuvant can make all the difference in whether a vaccine works.

JOE PALCA, BYLINE: It's relatively easy to describe what an adjuvant is. Gregory Glenn is president of research and development at Novavax, one of the companies making a COVID-19 vaccine.

GREGORY GLENN: The definition of adjuvant is something you add to enhance, in the case of immunity, the immune response.

PALCA: That's what vaccines do. They essentially trick our bodies into making an immune response to a specific virus or bacterium, so if something dangerous comes along, our immune systems will be ready. But Glenn says before it can prompt a response to a specific virus, the immune system has to be primed.

GLENN: When you inject a vaccine, the first immune cell that's of importance is a dendritic cell.

PALCA: Dendritic cells are part of what's called the innate immune system. These cells will respond to anything foreign that enters the body, coronavirus included.

GLENN: If they see something - they see a virus or bacteria, they become highly activated. And then they create a whole cascade of events.

PALCA: That cascade leads to the production of antibodies. And it's the antibodies that will recognize the specific virus of interest. Novavax's testing shows the adjuvant it's using is critical for its vaccine to work. And that's the case for many vaccines. But the strange thing is there aren't a lot of adjuvants out there. Bali Pulendran is a vaccine developer at Stanford University.

BALI PULENDRAN: We only think about adjuvants when there is a dire need, such as this pandemic, for example. Now everyone's interested in a faster response and a better response and a longer-lasting response. Or when it comes to special populations, such as the very young and the very old.

PALCA: Pulendran says for almost a century, scientists relied on a compound called alum to act as an adjuvant. It wasn't until the 1990s that new adjuvants started appearing on the scene. Now there are several more options. But Pulendran says more choices are needed.

PULENDRAN: This is the topic that needs - deserves better attention.

PALCA: That's a sentiment Corey Casper totally agrees with. He's the CEO of IDRI, the Infectious Disease Research Institute, and a proselytizer for adjuvant research. Casper says consider what the pharmaceutical company GSK did with its shingles vaccine. Just by adding an adjuvant...

COREY CASPER: It took a vaccine that had previously existed which was about 50% effective, and it needed 97% effective and not just in all people but in the hardest-to-protect people, who are the elderly, who typically make poor immune responses.

PALCA: Casper says the vaccine community has underestimated the importance of adjuvants. He's even got data suggesting that adjuvants alone might be capable of preventing infectious diseases. And he says that has enormous implications.

CASPER: Every time a new infection pops up, there's a race to develop a new vaccine for it. But what if you could give people the adjuvant alone and didn't have to develop a vaccine? That adjuvant could be stockpiled. It could be, you know, made at millions of doses placed on the shelf, sitting there waiting for the next pandemic.

SALLIE PERMAR: Yeah, I think there's some truth to that.

PALCA: Sallie Permar is a vaccine researcher at Duke University. She says scientists now have a better idea of how adjuvants work and how they might be able to prevent disease all by themselves. But Permar says you have to be careful with adjuvants.

PERMAR: There are some downsides to having such a strong adjuvant effect.

PALCA: In the process of activating immune cells, adjuvants can also bring on some of the symptoms of disease, such as fever, malaise or inflammation. The GSK shingles vaccine works well because of its adjuvant. But many people complain about unpleasant side effects. Permar says it should be possible to develop new adjuvants that make a vaccine work better while minimizing these side effects.

PERMAR: There is a whole science awaiting us in vaccines that lies in adjuvants.

PALCA: With so much attention being paid to vaccines now, that science might not be far off.

Joe Palca, NPR News.

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