The Food and Drug Administration on Wednesday approved the U.S.’s first flu shot that uses mRNA technology: mFlusiva, from drugmaker Moderna. In a late-stage trial, mFlusiva was found to be about 27% more effective than a standard flu shot. That’s because mRNA vaccines can be manufactured much faster than traditional vaccines, allowing scientists to better match circulating influenza strains. Moderna said it takes two to three months from picking the strain to rolling out its flu shot, compared with about six months for traditional flu shots. The traditional flu shot ranges in effectiveness from 22% to 56%, according to the Mayo Clinic.