The Influenza pandemic of 1918 was a serious pandemic of influenza. It lasted for three years, from January 1918 to December 1920. About 500 million people were infected across the world with a population of 1.80 billion people. The pandemic spread to remote Pacific Islands and the Arctic. It killed 50 million to 100 million people— three to five percent of the world's population at the time. This means it was one of the deadliest natural disasters in human history.