What if mRNA vaccines could be made more powerful and less irritating? Scientists at the University of Pennsylvania have found a way to do just that—by tweaking a key molecule in the vaccine’s delivery system. Using a century-old chemical trick called the Mannich reaction, they added anti-inflammatory phenol groups to the lipids that carry mRNA into cells. The result? A new class of lipids that reduce side effects, boost gene-editing success, fight cancer more effectively, and supercharge vaccines like those for COVID-19. This breakthrough could change how we build the next generation of vaccines and therapies.