effect of evidence updates on key determinants of measles vaccination impact a dynamice CORD-Papers-2022-06-02 (Version 1)

Title: Effect of evidence updates on key determinants of measles vaccination impact: a DynaMICE modelling study in ten high-burden countries
Abstract: BACKGROUND: Model-based estimates of measles burden and the impact of measles-containing vaccine (MCV) are crucial for global health priority setting. Recently evidence from systematic reviews and database analyses have improved our understanding of key determinants of MCV impact. We explore how representations of these determinants affect model-based estimation of vaccination impact in ten countries with the highest measles burden. METHODS: Using Dynamic Measles Immunisation Calculation Engine (DynaMICE) we modelled the effect of evidence updates for five determinants of MCV impact: case-fatality risk contact patterns age-dependent vaccine efficacy the delivery of supplementary immunisation activities (SIAs) to zero-dose children and the basic reproduction number. We assessed the incremental vaccination impact of the first (MCV1) and second (MCV2) doses of routine immunisation and SIAs using metrics of total vaccine-averted cases deaths and disability-adjusted life years (DALYs) over 20002050. We also conducted a scenario capturing the effect of COVID-19 related disruptions on measles burden and vaccination impact. RESULTS: Incorporated with the updated data sources DynaMICE projected 253 million measles cases 3.8 million deaths and 233 million DALYs incurred over 20002050 in the ten high-burden countries when MCV1 MCV2 and SIA doses were implemented. Compared to no vaccination MCV1 contributed to 66% reduction in cumulative measles cases while MCV2 and SIAs reduced this further to 90%. Among the updated determinants shifting from fixed to linearly-varying vaccine efficacy by age and from static to time-varying case-fatality risks had the biggest effect on MCV impact. While varying the basic reproduction number showed a limited effect updates on the other four determinants together resulted in an overall reduction of vaccination impact by 0.58% 26.2% and 26.7% for cases deaths and DALYs averted respectively. COVID-19 related disruptions to measles vaccination are not likely to change the influence of these determinants on MCV impact but may lead to a 3% increase in cases over 20002050. CONCLUSIONS: Incorporating updated evidence particularly on vaccine efficacy and case-fatality risk reduces estimates of vaccination impact moderately but its overall impact remains considerable. High MCV coverage through both routine immunisation and SIAs remains essential for achieving and maintaining low incidence in high measles burden settings. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12916-021-02157-4.
Published: 2021-11-17
Journal: BMC Med
DOI: 10.1186/s12916-021-02157-4
DOI_URL: http://doi.org/10.1186/s12916-021-02157-4
Author Name: Fu Han
Author link: https://covid19-data.nist.gov/pid/rest/local/author/fu_han
Author Name: Abbas Kaja
Author link: https://covid19-data.nist.gov/pid/rest/local/author/abbas_kaja
Author Name: Klepac Petra
Author link: https://covid19-data.nist.gov/pid/rest/local/author/klepac_petra
Author Name: van Zandvoort Kevin
Author link: https://covid19-data.nist.gov/pid/rest/local/author/van_zandvoort_kevin
Author Name: Tanvir Hira
Author link: https://covid19-data.nist.gov/pid/rest/local/author/tanvir_hira
Author Name: Portnoy Allison
Author link: https://covid19-data.nist.gov/pid/rest/local/author/portnoy_allison
Author Name: Jit Mark
Author link: https://covid19-data.nist.gov/pid/rest/local/author/jit_mark
sha: 0df014777a9ff2737d6b648ee23c9de83b3d0f14
license: cc-by
license_url: https://creativecommons.org/licenses/by/4.0/
source_x: Medline; PMC; WHO
source_x_url: https://www.medline.com/https://www.ncbi.nlm.nih.gov/pubmed/https://www.who.int/
pubmed_id: 34784922
pubmed_id_url: https://www.ncbi.nlm.nih.gov/pubmed/34784922
pmcid: PMC8594955
pmcid_url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8594955
url: https://doi.org/10.1186/s12916-021-02157-4 https://www.ncbi.nlm.nih.gov/pubmed/34784922/
has_full_text: TRUE
Keywords Extracted from Text Content: MCV2 measles-containing vaccine measles COVID-19 DynaMICE zero-dose children MCV SIAs V3 c Non-COVID-19' scenario under-immunised I-infectious B' stem Afghanistan Rubella Nigeria, https://doi highburden Niger Vaccine https://github children COVID-19 pandemic [6 zero-dose com/lshtm-vimc/dynamice Figure S1 MCV2 ω measles people Figure S3 SIR DynaMICE zero-dose children Fig. 3C Portnoy's Infants DR Congo measles vaccine countryspecific Non-COVID-19' and ' org/10.1186/s12916-021 [9] Fig. 3D [3] 2-10 Fortran-95 B measles-containing vaccine vaccine R-recovered Figure S1 S2-Calculating − contact matrix COVID-19 service MCV stratum Non-COVID-19' scenario [28] Measles first-dose measles basic reproduction Congo c denotes matrix Figure S2 COVID-19 Fig. 2 Figure S1 ): S1-Model 1, 2 WHO-UNICEF LMICs https://www.who.int/entity/immunization/monitoring_surveillance/ data/Summary_Measles_SIAs.xls) Vaccine https://immunizationdata.who.int/pages/coverage/mcv AP KA https://population.un.org/wpp/ Competing interests MJ measles DynaMICE BMC Medicine UK PK HT
Extracted Text Content in Record: First 5000 Characters:Background: Model-based estimates of measles burden and the impact of measles-containing vaccine (MCV) are crucial for global health priority setting. Recently, evidence from systematic reviews and database analyses have improved our understanding of key determinants of MCV impact. We explore how representations of these determinants affect model-based estimation of vaccination impact in ten countries with the highest measles burden. Methods: Using Dynamic Measles Immunisation Calculation Engine (DynaMICE), we modelled the effect of evidence updates for five determinants of MCV impact: case-fatality risk, contact patterns, age-dependent vaccine efficacy, the delivery of supplementary immunisation activities (SIAs) to zero-dose children, and the basic reproduction number. We assessed the incremental vaccination impact of the first (MCV1) and second (MCV2) doses of routine immunisation and SIAs, using metrics of total vaccine-averted cases, deaths, and disability-adjusted life years (DALYs) over 2000-2050. We also conducted a scenario capturing the effect of COVID-19 related disruptions on measles burden and vaccination impact. Results: Incorporated with the updated data sources, DynaMICE projected 253 million measles cases, 3.8 million deaths and 233 million DALYs incurred over 2000-2050 in the ten high-burden countries when MCV1, MCV2, and SIA doses were implemented. Compared to no vaccination, MCV1 contributed to 66% reduction in cumulative measles cases, while MCV2 and SIAs reduced this further to 90%. Among the updated determinants, shifting from fixed to linearly-varying vaccine efficacy by age and from static to time-varying case-fatality risks had the biggest effect on MCV impact. While varying the basic reproduction number showed a limited effect, updates on the other four determinants together resulted in an overall reduction of vaccination impact by 0.58%, 26.2%, and 26.7% for cases, deaths, and DALYs averted, respectively. COVID-19 related disruptions to measles vaccination are not likely to change the influence of these determinants on MCV impact, but may lead to a 3% increase in cases over 2000-2050. Conclusions: Incorporating updated evidence particularly on vaccine efficacy and case-fatality risk reduces estimates of vaccination impact moderately, but its overall impact remains considerable. High MCV coverage through both routine immunisation and SIAs remains essential for achieving and maintaining low incidence in high measles burden settings. Keywords: Measles, Vaccination impact, Transmission dynamic model, Routine vaccination, Supplementary immunisation activity Background Measles is a highly contagious disease that may result in severe morbidity and mortality, particularly in young children and in settings with poor access to treatment. Vaccination is a safe and effective measure for measles prevention and control, as seen in high-income countries since its first licensure in 1961 [1] . The optimal age range of the first dose of measles-containing vaccine (MCV1) depends on the local variation in seasonality, birth rate, and access to care [2] . In settings with ongoing measles transmission, the World Health Organization (WHO) recommends delivering MCV1 to children of 9 months old, and following up with the second dose (MCV2) for children at 15-18 months old [3] . In addition, among countries with weak health systems, supplementary immunisation activities (SIAs) through vaccination campaigns are highly effective in protecting under-immunised and zero-dose children by closing immunity gaps and interrupting measles transmission [3] . Vaccination contributes to the establishment of high levels of population immunity required for measles elimination, which is verified by the absence of endemic measles transmission for at least 36 months [4] . In 2011, the Global Measles and Rubella Strategic Plan was set up with a goal to achieve measles elimination in at least five WHO regions by the end of 2020 [5] . However, coverage of MCV1 has stagnated since 2010 in many countries and has been set back in 2020 due to routine immunisation service disruptions and mass vaccination campaign suspensions caused by the COVID-19 pandemic [6] . This has increased immunity gaps and the risk of measles outbreaks. Strategic investments to improve measles vaccine coverage globally are partially informed by model-based estimates of measles burden and the impact of vaccination. An analysis conducted by the Vaccine Impact Modelling Consortium found that 57% of all vaccinerelated mortality reduction was due to measles vaccination in 98 low-and middle-income countries (LMICs) between 2000 and 2019 [7] . An updated analysis for 112 LMICs found that 47 million measles deaths were estimated to be averted from vaccination activities occurring between 2000 and 2030 [8] . However, such estimates are highly dependent on our knowledge of key determinants of measles incidence and mortality as well as vaccination impact. Over the
Keywords Extracted from PMC Text: Rubella ω Congo [3] measles-endemic measles basic reproduction Niger × Xa, k under-immunised measles zero-dose Fig. 2 low- people c} measles vaccine first-dose stem COVID-19 pandemic [6 MCV La, k matrix measles-containing vaccine Nigeria, Figure S2 MCV2 COVID-19 Afghanistan Ya, k Fig. 3D Vaccine c denotes c×La,k children DR Congo − c Fig. 3C [18].(ii)a 'COVID-19 Figure S3 c=(Xa Infants Fortran-95 https://github.com/lshtm-vimc/dynamice DynaMICE " 's Non-COVID-19' LMICs COVID-19 service contact matrix Portnoy's zero-dose children WHO-UNICEF SIR Measles
Extracted PMC Text Content in Record: First 5000 Characters:Measles is a highly contagious disease that may result in severe morbidity and mortality, particularly in young children and in settings with poor access to treatment. Vaccination is a safe and effective measure for measles prevention and control, as seen in high-income countries since its first licensure in 1961 [1]. The optimal age range of the first dose of measles-containing vaccine (MCV1) depends on the local variation in seasonality, birth rate, and access to care [2]. In settings with ongoing measles transmission, the World Health Organization (WHO) recommends delivering MCV1 to children of 9 months old, and following up with the second dose (MCV2) for children at 15–18 months old [3]. In addition, among countries with weak health systems, supplementary immunisation activities (SIAs) through vaccination campaigns are highly effective in protecting under-immunised and zero-dose children by closing immunity gaps and interrupting measles transmission [3]. Vaccination contributes to the establishment of high levels of population immunity required for measles elimination, which is verified by the absence of endemic measles transmission for at least 36 months [4]. In 2011, the Global Measles and Rubella Strategic Plan was set up with a goal to achieve measles elimination in at least five WHO regions by the end of 2020 [5]. However, coverage of MCV1 has stagnated since 2010 in many countries and has been set back in 2020 due to routine immunisation service disruptions and mass vaccination campaign suspensions caused by the COVID-19 pandemic [6]. This has increased immunity gaps and the risk of measles outbreaks. Strategic investments to improve measles vaccine coverage globally are partially informed by model-based estimates of measles burden and the impact of vaccination. An analysis conducted by the Vaccine Impact Modelling Consortium found that 57% of all vaccine-related mortality reduction was due to measles vaccination in 98 low- and middle-income countries (LMICs) between 2000 and 2019 [7]. An updated analysis for 112 LMICs found that 47 million measles deaths were estimated to be averted from vaccination activities occurring between 2000 and 2030 [8]. However, such estimates are highly dependent on our knowledge of key determinants of measles incidence and mortality as well as vaccination impact. Over the past decade, there have been substantial advances to our knowledge of measles case-fatality risks (CFRs) [9], social contacts driving person-to-person infection transmission [10, 11], age-related vaccine efficacy [12], the ability of SIAs to reach zero-dose populations [13], and measles basic reproduction numbers [14]. Nonetheless, how this additional evidence on epidemiological, behavioural, and programmatic determinants affects estimates of vaccination impact has never been systematically explored. In this study, we investigated the extent to which recent evidence updates about these determinants affects model-based estimates of measles burden and vaccination impact. To do this, we used the Dynamic Measles Immunization Calculation Engine (DynaMICE), a population-based dynamic model of measles transmission that has been used to inform vaccination impact [7]. We incorporated the updated data sources of these determinants into the DynaMICE model and assessed their individual and combined effects on the estimation of MCV impact and the development of effective vaccination strategies. DynaMICE is an age-structured compartmental transmission model designed to assess the impact of measles vaccination globally. Susceptible individuals become infected after effective contact with an infectious person and remain immune once they recover from their infection. Infants are born with or without maternal antibodies, depending on the immunity of their mothers. The population is further divided according to their received number of measles-containing vaccine doses (see Fig. 1). The age structure is composed of weekly age classes for the first 3 years of age, with annual age classes thereafter up to 100 years. The force of infection is calculated by multiplying an age-dependent per-capita contact rate with the total number of infectious people in the population and the probability of transmission per contact. The latter is calculated by scaling the next-generation matrix to reach a target basic reproduction number (R0) of 16, and assuming the average duration of infectiousness is 14 days. Annual seasonality of measles transmission was also incorporated into the model structure. Maternal immunity was assumed to last for an average of 6 months after birth [15], while individuals who recover from measles disease or acquire effective vaccine protection develop lifelong immunity. Measles deaths are calculated by applying an age-specific CFR to the incidence of cases. The model was coded in R and Fortran-95, and the code is available in https://github.com/lshtm-vimc/dynamice. Details of model equations and parameters are
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