The flu pandemic that struck in the autumn of 1918 killed tens of millions worldwide. But it now seems that it had a widespread, and much milder, trial run.
Scandinavian health statistics record an unseasonable outbreak of flu in the summer of 1918. People who caught it were only a tenth as likely to die as those stricken in the autumn, but those who did catch it were mainly young adults – a hallmark of the autumn outbreak and a strong indication that the summer virus was closely related to it (The Journal of Infectious Diseases, DOI: 10.1086/524065).
Previous studies…
