This is part 25 of our coronavirus FAQ. Click here to read other installments: #Coronavirus the facts. Find the latest information and answers from experts on everything COVID-19.
How many people were infected by the Spanish flu?
The World Health Organization says that around 500 million people, or roughly a quarter of the global population at the time, were infected during the 1918 Spanish flu pandemic. About 40 million people died.
The Spanish flu started to spread around the world in the spring of 1918 before subsiding in the summer. But a second wave broke out in the fall, followed by a third at the beginning of 1919.
The second wave is believed to have been the deadliest phase of the pandemic, killing at least 20 million people.
In Japan, the pandemic had three waves between the fall of 1918 and the spring of 1921. Home Ministry records show that about 23.8 million people were infected and 390,000 died.
The majority of these infections occurred during the first wave of the outbreak, which struck in the fall of 1918. 21.2 million were infected and 260,000 died.
The second wave, which struck in the fall of 1919, was smaller, with 2.4 million infections and 130,000 deaths. However, the fatality rate was higher.
Will there be second and third waves of the coronavirus pandemic?
Professor Hamada Atsuo of Tokyo Medical University says that after the current outbreak subsides, a new wave of infections could break out this fall or winter. He says it could come even earlier, driven by a surge in travelers once Japan eases entry restrictions.
Hamada says it's impossible to tell whether the coronavirus pandemic will follow the course of the Spanish flu, but he says it is highly likely that there will be several waves of infection.
This information is accurate as of June 25.