Maurice Ralph Hilleman was a leading American microbiologist who specialized in vaccinology and developed over 40 vaccines, an unparalleled record of productivity. According to one estimate, his vaccines save nearly eight million lives each year. He has been described as one of the most influential vaccinologists ever. He has been called the "father of modern vaccines". Robert Gallo called Hilleman "the most successful vaccinologist in history". He has been noted by some researchers as having saved more lives than any other scientist in the 20th century.

The 1957–1958 Asian flu pandemic was a global pandemic of influenza A virus subtype H2N2 that originated in Guizhou in Southern China. The number of excess deaths caused by the pandemic is estimated to be 1–4 million around the world, making it one of the deadliest pandemics in history. A decade later, a reassorted viral strain H3N2 further caused the Hong Kong flu pandemic (1968–1969).