This Is How Your Body Builds Immunity

We encounter bacteria, viruses and parasites all the time, but how exactly does our immune system kill these dangerous pathogens? » Subscribe to Seeker! » Watch more Human! » Visit our shop at Vaccines are quite possibly the greatest thing that humans ever created. Vaccination has its roots in variolation, a technique developed by Asian physicians prior to the 1700s. The physicians would take dust from someone’s smallpox scab and blow it into their patient’s nose—the patient would experience a weaker version of smallpox, but then they’d be immune to it for life. Pretty cool, huh? And while variolation was far from perfect, when the alternative was contracting a potentially fatal version of smallpox, it was a good first step. And in the hundreds of years since, doctors have made huge advances in vaccination technology like Edward Jenner’s famous smallpox vaccine made from cowpox virus, or