Free levelled English reading practice. Read for meaning first, then use the full Speed Reading tool to time yourself and track your progress.
Vaccination works by exposing the immune system to a safe representation of a pathogen or one of its components, allowing immune memory to develop without the full danger of the disease. Edward Jenner’s 1796 smallpox experiment using cowpox is a famous milestone, though practices resembling inoculation existed earlier in Asia, Africa and the Ottoman world. Modern vaccines use varied technologies, including weakened or inactivated organisms, purified proteins, viral vectors and mRNA. High vaccination coverage can reduce transmission as well as protect individuals, which is particularly important for people who cannot receive certain vaccines. Their success has made some once-feared diseases rare, creating the paradox that the benefits can become less visible precisely because vaccination works.
