Fig 3. Example simulated time series of monthly cases for the five models (panels a–e).

Each model was parameterised to have a herd immunity threshold around 90% vaccine coverage, and experienced the same decrease in vaccine coverage over the same time span as Fig 1a. Qualitatively, we see that the effect of declining vaccine coverage is model-structure dependent. For the time series shown, the time to the first major outbreak varies between 10 years for FRED (panel d) to 18 years for the nonseasonal SEIR model (panel a).