Few medical interventions have saved more lives than vaccination. Smallpox, which killed hundreds of millions of people over centuries, was eradicated in 1980 through a global vaccination campaign. Polio, which once paralyzed tens of thousands of children annually, has been eliminated from most of the world. Measles, diphtheria, and whooping cough — diseases that filled hospital wards and orphanages within living memory — are now rare in countries with high vaccination coverage. This is one of the great achievements of modern medicine.
The principle behind vaccination is elegant. The immune system learns to recognize and fight pathogens by being exposed to them. A vaccine introduces a harmless version of that exposure — a weakened or inactivated pathogen, a protein fragment from its surface, or in the case of mRNA vaccines, instructions for the body to produce such a protein itself — allowing the immune system to build a memory response without the risk of actual disease.
The mRNA vaccine technology, deployed at scale for the first time during the COVID-19 pandemic, attracted enormous public attention and, alongside it, considerable misinformation. It is worth being clear: mRNA does not interact with DNA and cannot alter the genome. The instructions delivered by the vaccine are transient — they are used briefly to produce an immune-triggering protein, then degraded by normal cellular processes within days.
Herd immunity — the indirect protection that unvaccinated individuals receive when a sufficiently large proportion of the population is immune — requires different vaccination thresholds for different diseases. For measles, which is exceptionally contagious, roughly ninety-five percent of the population must be immune to prevent outbreaks. When coverage falls below that threshold, clusters of unvaccinated individuals become vulnerable to rapid transmission.
Vaccine hesitancy, fueled by misinformation spread through social media, poses a genuine public health challenge. Rebuilding trust requires honest communication about both the benefits and the real, if rare, risks of vaccination — and a medical community willing to engage with concerns rather than dismiss them. The science is clear, but science alone does not build the confidence that vaccination programs depend upon.