Ian and Jennifer Glynn, in The life and death of smallpox, confirm that bottles of "variolous matter" were carried to Australia for use as a vaccine, but think it unlikely the virus could have survived till 1789. In 2007, Christopher Warren offered evidence that the British smallpox may have been still viable. However, the only non-Aborigine reported to have died in this outbreak was a seaman called Joseph Jeffries, who was recorded as being of "American Indian" origin.W. S. Carus, an expert in biological weapons, has written that there is circumstantial evidence that smallpox was deliberately introduced to the Aboriginal population. However Carmody and the Australian National Universitys Boyd Hunter continue to support the chickenpox hypothesis. In a 2013 lecture at the Australian National University, Carmody pointed out that chickenpox, unlike smallpox, was known to be present in the Sydney Cove colony. He also suggested that all c. 18th century (and earlier) identifications of smallpox outbreaks were dubious because: "surgeons … would have been unaware of the distinction between smallpox and chickenpox – the latter having traditionally been considered a milder form of smallpox." During World War II, scientists from the United Kingdom, United States, and Japan (Unit 731 of the Imperial Japanese Army) were involved in research into producing a biological weapon from smallpox.
The latter view is frequently supported in the scientific community, particularly among veterans of the WHO Smallpox Eradication Program.On March 31, 2003, smallpox scabs were found inside an envelope in an 1888 book on Civil War medicine in Santa Fe, New Mexico. The envelope was labeled as containing scabs from a vaccination and gave scientists at the CDC an opportunity to study the history of smallpox vaccination in the United States. On July 1, 2014, six sealed glass vials of smallpox dated 1954, along with sample vials of other pathogens, were discovered in a cold storage room in an FDA laboratory at the National Institutes of Health location in Bethesda, Maryland. The smallpox vials were subsequently transferred to the custody of the CDC in Atlanta, where virus taken from at least two vials proved viable in culture. After studies were conducted, the CDC destroyed the virus under WHO observation on February 24, 2015.In 2017, Canadian scientists recreated an extinct horse pox virus to demonstrate that the smallpox virus can be recreated in a small lab at a cost of about $100,000, by a team of scientists without specialist knowledge. This makes the retention controversy irrelevant since the virus can be easily recreated even if all samples are destroyed.