World Health Organization 15 January 2019 WHO measles mortality estimates, 2000-2009 Emily Simons Global Measles Management Meeting 17 March 2010

Overview Background Brief description of method Provisional results Next steps

World Health Organization Background World Health Organization 15 January 2019 3 progressively more refined models of measles mortality since 2000 Stein 2003, Wolfson 2007, Ferrari 2011 2011 model addresses QUIVER recommendations to incorporate: surveillance data dynamic transmission herd immunity objective definition for countries that have highly reliable surveillance data Country consultation: letters sent to 119 countries Dynamic in sense that susceptible in year x affects susceptibles in year x+1, but does not have bells and whistles of highly complex dynamic models because this requires far more data, most of which is not routinely available, and added benefit of this level of complexity appears minimal (E.g. there is no person-to-person contact matrix or age structure or subnational heterogeneity in coverage.) Herd immunity component may need some adjustment pending feedback from country consultation process. Definition for countries where surveillance data is more reliable than model estimates: countries that have eliminated measles or are in lowest quintile of national child mortality rates

Overview of 2011 measles mortality estimation method Annual country-specific cases estimated by method called state-space model Cases distributed across age groups Age, country, and year-specific CFRs applied to cases

State-space model For each country independently, model compares two data for each year: a) reported cases and b) number of susceptibles based on susceptible-infected-recovered model # of true cases estimated for year t, with random error added Subtract these cases from susceptibles, repeat process for year t+1 1,000 iterations give distribution of most likely number of cases for time series

15 January 2019

Age distribution 172,191 line-listed cases from 102 countries Outcome: age group Explanatory variables: GBD Region MCV1 coverage Predicted age distribution of reported measles cases by MCV1 coverage level and region

Case fatality ratios Age and country-specific CFRs from Wolfson IJE 2009 updated for new studies Nepal and India Indexed to U5MR to reflect evidence of decline in deaths due to pneumonia, diarrhoea and malnutrition

Provisional global estimated measles mortality and reported cases World Health Organization 15 January 2019 74% global mortality reduction over 2000-2009 79% reduction over 2000-2009 according to Lancet

New model vs. Lancet model measles mortality estimates 79% 74%

Estimated measles deaths and reduction in mortality since 2000* 79% 87% 26% 82% 15 January 2019 *provisional

Estimated total measles deaths in 2000 and 2009 % mortality reduction Lancet New model Region 2009 2000 93% 25602 385755 87% 52247 411631 AFR 91% <100 99% AMR 96% 4130 100008 79% 9540 46113 EMR 73% 157 585 667 EUR 48% 127817 244871 26% 88750 119618 SEAR 92% 1972 24701 82% 3876 21689 WPR 159679 755921 74% 154502 599721 Global

Next steps Respond to feedback from country consultation Many supportive responses, but some feel the data do not reflect their reality Will modify input data, may modify structural features like herd immunity Key challenge: how to identify when surveillance sensitivity has changed? Clearance: required to fit within estimates of overall declining child mortality and estimated declines in other causes of child mortality Challenge: non-V.P. diseases do not have annual surveillance/coverage data  very different methods, with much greater lag time Peer review

Back-up slides

Measles mortality estimates, African Region 87% 93%

Measles mortality estimates, Eastern Mediterranean Region 96% 79%

Measles mortality estimates, South-East Asia Region 48% 26%

Measles mortality estimates, Western Pacific Region 93% 82%