Punctuated Evolution of Influenza Virus Neuraminidase (A/H1N1) under Opposing Migration and Vaccination Pressures

Figure 4

The beneficial effects of vaccination programs are cumulative, and those of small programs accumulate more slowly. The small US Army program, begun in 1944, did not show beneficial effects until 1950. The way that this happened at the aa level is shown here for ℛ(17) for the MZ and KD scales. A sketch shows the effects of individual mutations leading up to, and including, the first 1949-1950 A-B vaccination punctuation. The dominant effect of I19T between Rome 49 and Ft Warren 50, near the center of the 7–35 transmembrane segment, is clear.