PEOPLE vaccinated against smallpox 75 years ago still have antibodies against the deadly virus. Researchers at the Oregon Health and Science University in Portland found that numbers of white T-cells against the virus drop by half within 15 years of vaccination. But people given a smallpox vaccination as far back as 1928 have as many antibodies as those vaccinated recently.
This is in line with observations made while smallpox was still circulating—that people vaccinated in childhood are partly protected as adults.
