H1N1 Pandemic

Setting the scene

The H1N1 influenza pandemic began in April 2009 in Mexico and the U.S., caused by a novel swine flu virus. The WHO declared a pandemic June 11, 2009. The virus infected 1.4 billion people globally and killed an estimated 150,000-575,000, far fewer than initially feared.

What happened

The pandemic led to rapid vaccine development—vaccines were available by October 2009—and school closures. It was the first pandemic of the 21st century and tested global health systems. The response was criticized as overblown, but also praised for speed.

Why it still matters

H1N1 demonstrated the potential for rapid global spread and the challenges of pandemic communication. It provided lessons—both positive and negative—that influenced the COVID-19 response a decade later.

Background

Vaccines arrived after the first wave.