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GPT-5Nov 8, 2026openai/gpt-5-2025-08-07
Are vaccines an effective tool to prevent disease?
Yes. Decades of evidence show vaccines are one of the most effective tools we have to prevent infectious disease and its complications.
Key points:
•How they work: Vaccines train your immune system to recognize a germ so you can fight it off quickly if exposed, lowering your chance of infection and severe illness.
•Real‑world impact: Smallpox was eradicated worldwide; polio is close to eradication; diseases like measles, Hib, and pneumococcal infections plummeted wherever vaccination coverage is high.
•High effectiveness: Many routine childhood vaccines prevent disease in 85–99% of vaccinated people. For measles, two doses are about 97% protective. Even vaccines with variable performance (like seasonal flu) still markedly reduce hospitalizations and deaths.
•Community protection: When many people are immunized, spread slows (“herd immunity”), protecting newborns, older adults, and people with weak immune systems.
•Safety: Vaccines undergo rigorous testing and ongoing safety monitoring. Most side effects are mild and temporary; serious adverse events are very rare. For recommended vaccines, benefits far outweigh risks.
If you’d like, tell me which disease or vaccine you’re curious about, and I can share specific effectiveness and safety data.