I found a newspaper message from the 19th century that described a flu that gave pneumonia and undertakers hadn’t seen anything like it since the Cholera epidemics, this article was from Spain around 1840’s.
The article states under the header “news from Spain” :
“In the last days a terrible [amount of] dying has transpired that the gravediggers state that they have no recollection [of such a thing] since the Cholera. Most people die of lung and chest complications that follow from the flu.”
27-01-1848
Old Dutch is actually a lot like Old English, they’re both sister languages. Supposedly speakers of those languages were able to (mostly) understand each other, similarly to a dialect.