Getting sick and recovering from a disease provides stronger, longer-lasting immunity than vaccination.
While infection does generate immune memory, it comes at tremendous cost: measles causes 1-2 deaths per 1,000 cases and serious complications like encephalitis; polio causes permanent paralysis in 1 in 200 infected children. Vaccine immunity, by contrast, protects without the disease burden. For many vaccines (tetanus, hepatitis B, meningococcal), vaccine-induced immunity is actually more durable and reliable than natural infection. A 2021 study in NEJM found that hybrid immunity (vaccination plus prior infection) provided superior protection against COVID-19 compared to either alone, suggesting vaccine immunity wasn't inferior but rather complementary to natural exposure. For diseases like pertussis, vaccine immunity wanes, requiring boosters, but that doesn't make it inferior; it reflects a rational trade-off between risk and protection. The question shouldn't be 'natural versus vaccine,' but rather 'should we accept disease risk to achieve immunity?' The answer for serious infections is clearly no.