Vaccine hesitancy is an ongoing structural problem that impacts humanity during every pandemic occurrence.

The World Health Organization named vaccine hesitancy one of the top 10 threats to global health in January 2019 — nearly a year before whispers of a mysterious illness in Wuhan, China. The reasons why people may be reluctant or refuse vaccines are complex, the WHO wrote, but include complacency and a lack of confidence in the shots or their health officials. The agency estimated that 1.5 million lives could be saved globally if vaccines were more widely accepted. What's happened in the U.S. during the Covid pandemic is a prime example of the deadly toll that can occur that can accompany vaccine hesitancy. The Kaiser Family Foundation estimates that nearly a quarter million Covid deaths from June 2021 through March were among the unvaccinated. This represents 60 percent of Covid deaths reported in that time period. But vaccine hesitancy is not new. People have been questioning vaccines since they were first introduced in the 18th century to combat smallpox, which, at the time, was killing up to half a million people a year in Europe alone. In 1910, Canadian physician Dr. William Osler wrote that he remained resolute in the benefits of smallpox vaccinations, despite anti-vaccine sentiments of the time. "I do not see how anyone who has gone through epidemics as I have, or who is familiar with the history of the subject, and who has any capacity left for clear judgment, can doubt its value," Osler wrote. The New England Journal of Medicine later published his writings. He went a step further and offered to take 20 people — half of them vaccinated and the other half unvaccinated — into a smallpox outbreak, predicting that half of those who refused the vaccines would ultimately die. "I will make this promise — neither to jeer nor to jibe when they catch the disease, but to look after them as brothers," Osler wrote. "And for the four or five who are certain to die, I will try to arrange the funerals with all the pomp and ceremony of an antivaccination demonstration." (It's unclear, however, whether anyone took Osler up on his offer.)