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. 2022 Oct 11;10(11):e1612–e1622. doi: 10.1016/S2214-109X(22)00358-8

Figure 5.

Figure 5

Prediction of ongoing influenza activity when COVID-19 PHSMs are relaxed in April, 2022, (before the summer season) with proactive vaccination programmes (one-off vaccination timing, duration, and rate) to mitigate the excess influenza activity in nine locations and countries

The forecast of upcoming seasons was evaluated on the basis of the predictive model framework by fitting the susceptible–vaccinated–infected–recovered–susceptible models on influenza activity (observed incidence) data from October, 2017, to January, 2020, and accounting for increased susceptibility and the reduced effect of COVID-19 PHSMs on influenza by location and country. Red lines represent the observed incidence rate, and blue shaded regions indicate the period under COVID-19 PHSMs for each location. Light green shaded regions indicate the routine vaccination periods for each location. Solid black lines represent the mean forecast (in 1000 simulations) of the incidence rate for the 2022 summer season under no proactive vaccination or intervention for influenza, with grey shaded areas representing 2·5–97·5th quantiles. Dashed black lines represent the mean forecast of infection rate under a one-off vaccination programme to mitigate the excess infection burden in the first upcoming season of influenza. The vaccination start timing was set to the day when the incidence rate crossed a predefined threshold and the vaccination period (yellow shaded area) was optimised to achieve baseline activity (as was in the 2017–19 seasons) with a projected vaccination rate of 0·05 per week of the total susceptible population. Blue lines represent the proportion of the susceptible population with (solid line) and without (dashed line) vaccination. We did this prediction for successive seasons until December, 2024. The UK and Australia are not shown because the COVID-19 pandemic started after their respective influenza seasons had concluded. ILI+ proxy=combination of influenza positivity rate and influenza-like illness rate. PHSMs=public health and social measures.