The 1968 pandemic that redefined how viruses jump across borders

Gardening · Published 18 October 2026 Swipe more like this →

In short: In 1968, a new strain of influenza emerged that would kill up to four million people globally. While dubbed the 'Hong Kong flu,' its origins remain a subject of geopolitical mystery, illustrating how a single genetic shift can trigger a worldwide health crisis in just a few months.

An H3N2 variant of influenza A triggered the 1968 pandemic. It emerged through a process called antigenic shift, where genes from multiple subtypes are reassorted to create a novel virus. While it was initially viewed by some as a variant of older strains, it was distinct enough to trigger a global crisis, killing between one and four million people between 1968 and 1970.

The geographical origin of the virus is contested. While it was first recorded in British Hong Kong on July 13, 1968, reports suggest it may have originated in mainland China. Newspapers reported respiratory illness in Guangdong Province on July 11, 1968, and in southeastern China the following day. However, due to strained diplomatic relations and a lack of etiological data at the time, it remains unconfirmed whether the virus originated in the central provinces of Sichuan, Gansu, Shaanxi, and Shanxi.

The virus spread with varying intensity. In Hong Kong, it affected about 15% of the population (roughly 500,000 people) over six weeks with relatively mild symptoms. In contrast, some regions faced severe disruptions. In West Germany, the death toll was high enough that garbage collectors had to bury the dead due to a lack of undertakers, and in France, half the workforce was bedridden. The virus also traveled via troop movements from the Vietnam War into the United States, where it didn't become widespread until December 1968.

The pandemic's behavior was unique; many countries, like the UK and Japan, saw repeated introductions of the virus in late 1968 without immediate large-scale outbreaks. These areas often didn't see severe epidemics until the following winter of 1969–1970. This delayed spread highlights the complexity of how novel viruses interact with existing populations and seasonal viruses, such as the influenza B virus that co-circulated in Japan during the same period.

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