Vaccines don’t work against some viruses. CRISPR might one day fix that

Two centuries isn’t a bad run for a medical technology. But while vaccination has prevented hundreds of millions of deaths since 1796, when Edward Jenner inoculated a boy with cowpox to prevent smallpox, there’s clearly room for improvement: Vaccines are risky or ineffective in people with compromised immune systems, they don’t even exist for several viral diseases, and flu vaccines, in particular, often fail in the elderly.