Practice question

First successful vaccine in history targeted smallpox, a highly contagious severe disease caused by variola major and minor viruses double-stranded DNA orthopoxvirus with case fatality 30 percent, disfiguring pustular rash progressing to scabs, blindness and death, responsible for 300-500 million deaths in 20th century alone. While variolation practice of inoculating smallpox pus existed in China and Turkey with significant risk, Jenner in 1798 demonstrated safer cowpox inoculation conferring protection without causing disseminated smallpox. Subsequent mass vaccination campaigns through 19th and 20th centuries using vaccinia virus, closely related orthopoxvirus propagated in calf lymph and later cell culture, administered via scarification with bifurcated needle, produced characteristic scar. Global eradication effort intensified by World Health Organization led by Donald Henderson implemented ring vaccination surveillance containment strategy, culminating in last natural case Ali Maow Maalin Somalia 1977 and declaration of eradication 1980. Smallpox remains only human disease eradicated, validating concept herd immunity, cold chain and collaboration, providing model for polio eradication attempts and establishing vaccinia vector platform for recombinant vaccines.