Fig. 2

Monthly projected age-adjusted immunity profiles from September 2019 to December 2021. The changes in coverage took effect in April 2020. The black dotted line shows the herd immunity threshold for measles before the COVID-19 physical distancing measures, 0.93[0.92-0.94] and the brown dotted line shows the herd immunity threshold during COVID-19 physical distancing measures, 0.86[0.83–0.89], assuming the lockdown measures are still in effect. The bold lines and shaded region in each scenario, i.e. a. no reduction, b. 15% reduction, c. 50% reduction, and d. 100% reduction, indicate the median estimates and the uncertainty of the predicted immunity quantified as the 95% quantiles of the bootstrap analysis. There was a quick decline of predicted immunity over the study period that was based on assumed reduction in routine coverage