How do you spell "H1N1"?

From Michael Wigglesworth's "God's Controversy with New England" (1662):

Our healthfull dayes are at an end,
and sicknesses come on
From yeer to yeer, becaus our hearts
away from God are gone.
New-England, where for many yeers
you scarcely heard a cough,
And where Physicians had no work,
now finds them work enough.

Now colds and coughs, and Rhewms, and sore-throats,
do more and more abound:
Now Agues sore and feavers strong
in every place are found...