The FDA approves Moderna's mRNA flu vaccine mFlusiva (mRNA-1010) for adults 50+ after initially refusing review. The vaccine targets four common flu strains causing up to 5M severe cases and 650,000 deaths annually per WHO.

Approval covers ages 50-64 based on Phase 3 trial with 40,805 adults across 11 countries, plus accelerated approval for 65+. Trial showed mRNA-1010 superior to standard-dose vaccines for preventing influenza-like illness, though adverse events (injection-site pain, fatigue, headache, myalgia) were more frequent but mostly mild to moderate.

FDA initially rejected review, claiming comparator vaccine didn't represent best standard of care and preferring higher-dose comparator for older adults. Critics called move political after director overruled career scientists; law professor Richard Hughes IV said it served "a predetermined anti-vaccine agenda." FDA reversed within a week, having previously approved the comparator.

mRNA vaccines offer advantages: high efficacy, rapid development, adaptability, no live viruses, fewer side effects for immunocompromised, no DNA alteration risk. mRNA breaks down quickly after delivering instructions.