August 4, 2022 – Most vaccines are not one-time offers. You need a series of boosters to build your immunity against COVID-19, tetanus, and other infectious threats over time. This can mean multiple visits to a health care provider, costing you time and sometimes money.
But what if you could get a single hit that gets stronger every time you need extra protection?
Researchers at the Massachusetts Institute of Technology (MIT) have developed microparticles that could be used to create self-boosted vaccines that deliver their contents at carefully defined times. In a new study published in the journal Scientists progressthe scientists describe how they tune the particles to release the goods at the right time and offer ideas on how they can keep the particles stable until then.
How self-stimulating vaccines might work
The team developed tiny particles that look like coffee cups – except instead of your favorite brew, they’re filled with vaccine.
“You can put the lid on and then inject it into the body, and once the lid breaks, whatever’s in there is released,” says study author Ana Jaklenec, PhD, a researcher at Koch Institute for Integrative Cancer Research at MIT.
To make the tiny cups, the researchers use various polymers (synthetic plastic-like materials) already used in medical applications, such as dissolvable stitches. Then they fill the cups with dried vaccine material combined with sugars and other stabilizers.
Particles can be made in different shapes and refined using polymers with different properties. Some polymers last longer in the body than others, so their choice helps determine how long everything will remain stable under the skin after taking the hit and when the particles will release their cargo. It could be days or months after the injection.
One of the challenges is that as the particles open up, the environment around them becomes more acidic. The team is working on ways to reduce this acidity to make the vaccine material more stable.
“We have ongoing research that has produced some really, really exciting results on their stability and that shows you’re able to keep really sensitive vaccines stable for a good period of time,” says study author Morteza Sarmadi, PhD, research specialist. at the Koch Institute.
The potential impact on public health
This research, funded by the Bill & Melinda Gates Foundation, began with the developing world in mind.
“The intention was actually to help people in developing countries, because often people don’t come back for a second injection,” says study author Robert Langer, ScD, a professor at the Institute. David H. Koch at MIT.
But a single plan could also benefit the developed world. One reason is that self-stimulating vaccines could help those who receive one achieve higher antibody responses than they would with a single dose. This could mean greater protection for the person and the population, because as people develop stronger immunity, germs may have less chance to evolve and spread.
Take the COVID-19 pandemic, for example. Only 67% of Americans are fully vaccinated, and most people eligible for the first and second boosters did not receive them. New variants, such as recent Omicron variants, continue to emerge and infect.
“I think these variants would have been much less likely to occur if everyone who was vaccinated the first time had been given repeat shots, which they didn’t,” Langer says.
Self-stimulating vaccines could also benefit infants, children who fear injections, and older people who have difficulty obtaining health care.
Also, because the vaccine material is encapsulated and its release can be staggered, this technology could help people receive multiple vaccines at the same time that now need to be administered separately.
What happens after
The team is testing self-boosted polio and hepatitis vaccines in non-human primates. A small trial in healthy humans could follow in the next few years.
“We believe this technology has very high potential and we hope it can be developed into the human phase very soon,” says Jaklenec.
In smaller animal models, they are exploring the potential of self-boosted mRNA vaccines. They also work with scientists studying HIV vaccines.
“There have been recent advances where very complex diets seem to work, but they’re not practical,” says Jaklenec. “And so, that’s where this particular technology could be useful, because you have to prime and boost with different things, and it allows you to do that.”
This system could also extend beyond vaccines and be used to deliver cancer therapies, hormones and biologics in one shot.
Through new work with researchers at Georgia Tech University, the team will investigate the potential of delivering self-stimulating vaccines through 3D-printed microneedles. These vaccines, which would stick to your skin like a band-aid, could be self-administered and rolled out globally in response to local outbreaks.