Sartori, Ana Marli Christovam; Nascimento, Andréia de Fátima; Yuba, Tânia Yuka; Soárez, Patrícia Coelho de; Novaes, Hillegonda Maria Dutilh

doi:10.1590/S0034-8910.2015049006058

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Sumário

Review • Rev. Saúde Pública 49 • 2015 • https://doi.org/10.1590/S0034-8910.2015049006058 copiar

Métodos e desafios da avaliação do impacto na saúde de programas de vacinação na América Latina

Autoria SCIMAGO INSTITUTIONS RANKINGS

RESUMO

OBJETIVO

Descrever métodos e desafios enfrentados na avaliação do impacto de programas de vacinação, com foco nas vacinas pneumocócica conjugada e de rotavírus nos países da América Latina e Caribe.

MÉTODOS

Para esta revisão narrativa, foi realizada busca nas bases de dados Medline e Lilacs, usando os termos "rotavirus", "pneumococcal", "conjugate vaccine", "vaccination", "program", e "impact". A busca foi estendida à literatura cinza no Google Acadêmico. Não houve limitação por ano de publicação. Foram incluídos estudos originais de avaliação do impacto dos programas de vacinação de pneumococo e rotavírus na América Latina e Caribe, publicados em inglês, espanhol ou português.

RESULTADOS

Foram identificados 207 artigos. Após remover duplicatas e avaliar elegibilidade, 33 estudos foram revisados, 25 sobre programas de vacinação de rotavírus e oito de pneumococo. Estudos ecológicos, com análise de série temporal ou comparação de períodos antes e após a vacinação, foram mais frequentes. As principais fontes de dados foram: sistemas de informação em saúde; sistemas de vigilância de base populacional, sentinela ou laboratorial; relatórios estatísticos; e prontuários médicos de um ou poucos serviços de saúde. Poucos estudos utilizaram dados primários. Hospitalizações e mortes foram os principais desfechos avaliados.

CONCLUSÕES

Nos últimos anos, número significativo de avaliações do impacto dos programas de vacinação de pneumococo e rotavírus foram realizados nos países da América Latina e Caribe. Esses estudos foram conduzidos poucos anos após a implementação dos programas, preenchem os requisitos metodológicos básicos e sugerem impacto positivo dos programas. Futuras avaliações devem considerar questões metodológicas e desafios que surgiram nesses primeiros estudos conduzidos na região.

Avaliação do Impacto na Saúde; Programas de Imunização; Vacinação em Massa, organização & administração; Vacinas contra Rotavirus; Vacinas Pneumocócicas

Country	Vaccine introduction status or year of introduction^a		Health impact assessment of the vaccination program

	Pneumococcal	Rotavirus	Pneumococcal	Rotavirus
Latin America
Argentina	2012	No decision
Belize	Planning introduction	No decision
Bolivia	2014	2008		¹¹
Brazil	2010	2006	^1,50	^{2,8,9,10,13,17,21,22,29,33,39,45,48}
Chile	2011	No decision
Colombia	2011	2009	³⁸
Costa Rica	2008	Planning introduction
Ecuador	2010	2007
El Salvador	2010	2006		^11,59
Guatemala	2012	2010
Guyana	2011	2010
Honduras	2011	2009		¹¹
Mexico	2009	2007		^{14,15,20,30,43,44}
Nicaragua	2010	2006	⁷	³⁷
Panama	2010	2006	³⁵	^6,32,34
Paraguay	2012	2010
Peru	2009	2009
Suriname	No decision	No decision
Uruguay	2008	No decision	^25,26,41,42
Venezuela	No decision	2006		¹¹
The Caribbean^b
Bahamas	GAVI approved	GAVI plan
Barbados	2009	No decision
Cayman Islands		2009
Cuba	Planning introduction	No decision
Dominica	2010	No decision
Dominican Republic	2009	2012
Haiti	GAVI approved	2013
Jamaica	2010	No decision
Trinidad and Tobago	2009	No decision

Author/Year	Country	Study design/Methodological comments	Data source	Clinical syndrome	Outcome	Main results

Secondary data
De Oliveira¹¹ (2013)	Bolivia, El Salvador, Honduras, and Venezuela	Ecological (interrupted time-series analysis) Control: Argentina, which still had not introduced the vaccine into its national immunization program during the study period	Databases of the sentinel surveillance network of rotavirus diarrhea and records on hospitalizations and deaths from the ministries of health	All-cause diarrhea	Number of deaths and hospitalizations	Reductions in diarrhea-related deaths and hospitalization in all four countries as opposed to the control country
Rissardo⁴⁵ (2010)	Brazil (Parana state)	Ecological (comparison of years before and after vaccine introduction) Limitations: short observation period after vaccine introduction; lack of adjustment for secular trends	National health information system on hospitalizations	All-cause diarrhea	Number and rates of hospitalizations	Significant decrease of diarrhea-related hospitalizations observed in children under one year of age after vaccine introduction. No impact evidenced among children aged one to four years
Do Carmo⁹ (2011)	Brazil	Ecological (interrupted time-series analysis, comparing event rates after vaccine introduction with expected rates estimated from prevaccine years) Adjustment for secular and seasonal trends	National mortality information system; national hospital information system, which covers the public health system	All-cause diarrhea	Mortality and hospitalization rates	Decreased rates of under-five diarrhea-related mortality and hospital admissions in the first three years after vaccine introduction, with largest reduction among children under two years of age
Lanzieri²⁹ (2011)	Brazil	Ecological (comparison of years before and after vaccine introduction) Limitations: lack of adjustment for secular trends	Mortality information system; live birth information system	All-cause diarrhea	Mortality rates	Decreasing rates of diarrhea-related deaths previous to vaccine introduction
Gurgel²² (2011)	Brazil	Ecological (comparison of trends before and after vaccine introduction) Limitations: lack of adjustment for secular trends	National hospital information system (public health system)	All-cause diarrhea	Hospitalizations and deaths	Reduction in hospitalizations preceded the vaccine introduction
Fernandes¹⁷ (2014)	Brazil (Sao Paulo state)	Ecological (comparison of years before and after vaccine introduction)	National health information system (public health system)	All-cause diarrhea	Hospitalization rates by the human development index of each municipality and diarrhea-related hospitalization costs	Decreased rates of hospitalizations among under-five children in all categories of municipal development, with greater decrease in the least developed areas. Seasonal blunting in diarrhea hospitalizations. Savings in hospitalization costs in all municipal categories
Esparza-Aguilar¹⁴ (2009)	Mexico	Ecological (comparison of years before and after vaccine introduction)	National health information systems on mortality and population	All-cause diarrhea	Number of deaths and cumulative death rates	Decrease in diarrhea-related deaths previous to vaccine introduction. Greater mean annual reduction after vaccine introduction
Richardson⁴⁴ (2010)	Mexico	Ecological (comparison of years before and after vaccine introduction)	National health information system on mortality and population	All-cause diarrhea	Deaths	Decline in diarrhea-related deaths after vaccination
Quintanar-Solares⁴³ (2011)	Mexico	Ecological (comparison of years before and after vaccine introduction) Control: all-cause hospitalization	National health information system	All-cause diarrhea	Number of hospital admissions	Reduction in diarrhea-related hospitalizations only among children under 12 months of age in the first year after vaccine introduction, and among children under 24 months of age in the second year
Gastañaduy²⁰ (2013)	Mexico	Ecological (comparison of years before and after vaccine introduction)	National health informatics system Data were classified into three regions, according to indicators of economic development	All-cause diarrhea	Deaths according to regional human development index	Reduction in diarrhea-related mortality sustained for four years after vaccine introduction. Comparable declines across the three regions of different levels of development
Esparza-Aguilar¹⁵ (2014)	Mexico	Ecological (comparison of years before and after vaccine introduction) Control: all-cause hospitalization	National health informatics system	All-cause diarrhea	Hospitalization rates according to the human development index of the state	Reduction in diarrhea-related hospitalizations of children under 24 months of age in all regions after vaccine introduction. Clear blunting of seasonal peaks
Nieto Guevara³⁴ (2008)	Panama	Cross-sectional study (comparison of years before and after vaccine introduction) Limitations: short observation period	Statistics and medical records service database of one tertiary hospital	All-cause diarrhea	Number of hospitalizations; length of stay	No decrease in hospitalizations observed after vaccine introduction
Bayard⁶ (2012)	Panama	Ecological (comparison of years before and after vaccine introduction) Control: mean number of events in a prevaccination five-year period Limitations: short observation period	National mortality information system; hospital discharge database of five sentinel hospitals	All-cause diarrhea of presumed infectious origin	Mortality and hospital admissions	Decrease in diarrhea-related mortality and hospitalization rates after vaccine introduction
Yen⁵⁹ (2011)	El Salvador	Ecological (comparison of years before and after vaccine introduction) Limitations: data on catchment population for the sentinel hospitals unavailable	Sentinel surveillance system (seven hospitals); national surveillance for diarrhea-related healthcare visits (inpatient and outpatient) in public healthcare facilities	All-cause diarrhea and rotavirus-positive diarrhea	Hospitalization rates and healthcare visits	Decreases in both hospitalizations and healthcare visits due to diarrhea
Orozco³⁷ (2009)	Nicaragua	Ecological (comparison of years before and after vaccine introduction) Control: median number of events in a prevaccination four-year period. Limitations: Short observation period	National population-based surveillance for acute gastroenteritis events in healthcare facilities (Ministry of Health)	All-cause diarrhea	Number of outpatient visits and hospitalizations	Decreases in diarrhea-related hospitalizations and medical visits

Surveillance data

Molto³² (2011)	Panama	Ecological (monthly trend analysis – comparison of years before and after vaccine introduction) Control: all-cause hospitalizations Limitations: unknown catchment population for the sentinel sites	National surveillance for diarrhea (six hospitals)	All-cause diarrhea	Hospitalizations	Reduction in diarrhea-related hospitalizations. Greater reduction during rotavirus seasonal months. All regions showed reduction in the ratio of diarrhea-related to non-diarrhea hospitalizations in the second year after vaccine introduction

Laboratory-based surveillance data

Morillo³³ (2010)	Brazil (Sao Paulo state)	Descriptive. Retrospective analyses of data collected in a five-year period, including two years before and two years after vaccine introduction	Laboratory-based data from diarrhea surveillance	Rotavirus-positive diarrhea	Proportion of rotavirus and rotavirus genotype distribution	Decrease in the proportion of rotavirus-positive samples before vaccine introduction. Emergence of the G2P[4] genotype after vaccine introduction
Carvalho-Costa¹⁰ (2011)	Brazil	Ecological	Laboratory-based surveillance: data from regional rotavirus reference laboratories in 18 of the 27 Brazilian federated units	Rotavirus-positive diarrhea, genotype characterization	Frequency of rotavirus and genotype distribution	Reduction in the proportion of rotavirus-related diarrhea in the years after vaccine introduction. Emergence of the G2P[4] genotype in the year before vaccination, with decrease in its detection in the last year of observation, probably reflecting natural genotype oscillations
Pereira³⁹ (2011)	Brazil (Parana state)	Descriptive	Laboratory-based data from one tertiary hospital	Rotavirus-positive diarrhea	Proportion of rotavirus-positive samples	Decline in the proportion of rotavirus-positive cases two years before vaccine implementation
Dulgheroff¹³ (2012)	Brazil (Minas Gerais state)	Descriptive. Data from a four-year period after vaccine introduction were compared with prevaccination data from other studies conducted in the same region	Data from two laboratories that collect and analyze specimens from private and public hospitals and pediatric clinics from the region	Rotavirus-positive diarrhea and rotavirus genotype characterization	Proportion of rotavirus among hospitalized and outpatient acute gastroenteritis cases	Reduction in rotavirus-related diarrhea in comparison with prevaccination studies. Great reduction in genotype diversity with predominance of G2P[4]

Author/Year	Country	Study design	Data source	Clinical syndrome	Outcome	Main results
Primary data

Gouvea²¹ (2009)	Brazil (Rio de Janeiro, RJ)	Hospital-based survey including three years and a half before and one year after vaccine introduction	Primary data collection at the emergency room of one hospital. Data gathered from medical bulletins and patient records. Vital statistics obtained from the Brazilian Ministry of Health	All-cause diarrhea and laboratory-confirmed rotavirus diarrhea	Number of emergency room visits, hospitalizations and deaths, and genotype distribution	The study was unable to clearly show the impact of vaccination. Gastroenteritis visits and hospitalizations showed significant year-to-year variation. A gradual decrease in rotavirus strain diversity was observed in the prevaccination years
Safadi⁴⁸ (2010)	Brazil (Sao Paulo, SP)	Prospective cohort including years before and after vaccine introduction	Prospective primary data collection in a private hospital, with routine rotavirus testing for all under-five children hospitalized for acute gastroenteritis	All-cause diarrhea and rotavirus-positive diarrhea	Number of hospitalizations and genotype characterization	Reduction in the number of all-cause and rotavirus-related diarrhea hospitalizations; delay in the rotavirus seasonal peak; and predominance of G2P[4] genotype in the postvaccination period
Borges⁸ (2011)	Brazil (Goiania, GO)	Cross-sectional. Data collection restricted to the postvaccination period was compared with prevaccination studies conducted in the same region Limitations: small sample size, data collection in a period shorter than 1 year	Primary data collection in seven day care centers. Children were enrolled independent of gastrointestinal symptoms	Rotavirus-positive diarrhea, genotype characterization	Proportion of rotavirus-positive samples	Presence of rotavirus in 3.6% of all samples and 10.4% of samples from children with diarrhea were rotavirus-positive, which is less than what was previously observed by other studies in the region (14.4%-37.2%). G2P[4] was the predominant circulating genotype
Assis² (2013)	Brazil (Juiz de Fora, MG)	Cross-sectional, including pre- and postvaccination years. Limitations: small sample size, compromising genotype distribution analyses. Data cannot be generalized to the entire Country	A university virology laboratory	Rotavirus-positive diarrhea	Frequency of rotavirus-diarrhea and genotype characterization	Decrease in the proportion of rotavirus-positive diarrhea after vaccine introduction. The G1P[6] genotype was most frequent before vaccine introduction and replaced by the G2P[4] genotype in the year of vaccine introduction and after
Leboreiro³⁰ (2013)	Mexico	Case series. Retrospective (pre-vaccination) and prospective (post-vaccine introduction) analysis of a case series	Hospital medical records of children treated in one hospital, including the emergency room and hospital wards	All-cause diarrhea and rotavirus-positive diarrhea	Frequency and severity of diarrhea	Reduction in rotavirus-related diarrhea; reduction in rotavirus diarrhea severity among vaccinated children

Author/Year	Country	Study design	Data source	Clinical syndrome	Outcome	Main results
Secondary data

Afonso¹ (2013)	Brazil (five capitals)	Ecological (interrupted time-series analysis) Control: non-respiratory causes Limitations: short observation period after vaccine introduction (one year)	National hospitalization information system (public health system). Data from five capitals that had good data quality and high PCV-10 vaccination coverage	All-cause pneumonia	Hospitalization rates among children aged two months to two years	Significant declines in the hospitalization rates for pneumonia in three capitals (Belo Horizonte, Curitiba and Recife), but not in the other two (Sao Paulo and Porto Alegre). Prevaccination hospitalization rates for pneumonia varied substantially by city. Hospitalization rates for non-respiratory causes also decreased in all cities, but at a lower rate
Nieto Guevara³⁵ (2013)	Panama	Descriptive (retrospective), comparing a three-year period including pre- and postvaccination years. Involved indigenous population. Limitations: results cannot be generalized	Medical records of a secondary-level referral hospital, based on discharge diagnosis of pneumonia given by the treating physician and coded according to ICD	All-cause pneumonia	Hospitalization rates and transfers to the regional hospital among under-five children	Reduction in hospitalization rates and referrals for pneumonia were observed after vaccine introduction. Results cannot be generalized
Pírez⁴¹ (2011)	Uruguay	Descriptive (retrospective), comparing a three-year period before vaccine introduction with a one-year period after	A national tertiary referral pediatric hospital database, complemented by medical records, laboratory databases and reports from the national information system on notifiable diseases	All-cause pneumonia, pneumococcal pneumonia, pneumococcal meningitis	Hospitalization rates among children aged one month to 14 years	Reduction in hospitalization rates for pneumococcal pneumonia and pneumococcal meningitis after PCV-7 introduction. Non-vaccine serotypes 1, 5, 7F, 19A, and 24F became the most frequent causes of pneumococcal pneumonia after vaccine introduction. There were changes in the national hospital admissions aimed to decrease hospitalizations during the study. These changes did not affect the rates of hospital discharges for acute gastroenteritis, the control disease analyzed
Pirez⁴² (2014)	Uruguay	Descriptive (retrospective), comparing years before (2003-2007) and after (2009-2012) vaccine introduction	Microbiology laboratory database and patient records of a single site	All-cause pneumonia, pneumococcal pneumonia, pneumococcal serotypes	Hospitalization rates among children aged zero to 14 years	Significant reduction in hospitalization rates. A clear two-step reduction in hospitalization rates for pneumonia after each introduction of PCV (PCV-7 and PCV-13). Significant reduction in PCV-13 vaccine serotypes and increase in non-vaccine serotypes after the vaccination program implementation
Becker-Dreps⁷ (2014)	Nicaragua (León)	Descriptive, comparing a period before (2008-2010) and after (2011-2012) vaccine introduction. Control: healthcare visits due to diarrhea	Epidemiological database of 107 public health facilities (93 healthcare centers, 13 primary care centers, 1 public referral hospital)	Pneumonia	Hospitalization rates, outpatient visits among children aged 0 to 14 years and infant mortality	Reduction in hospitalization and outpatient visits for pneumonia and decrease in infant mortality after vaccine introduction. No changes in overall healthcare visits for diarrhea during the study period

Surveillance data

Hortal²⁵ (2007); Hortal²⁶ (2012)	Uruguay	Two prospective cohorts – a three-year study before²⁷ and a three-year study after²⁸ vaccine introduction	Population-based surveillance system carried out in two municipalities. The study was conducted in four hospitals (two public and two private)	All-cause pneumonia	Annual hospitalization rates; serotype distribution among under-five children	Hospitalization rates for pneumonia did not decline in the three-year prevaccination study. Significant reduction in hospitalization rates for pneumonia and changes in serotypes after vaccine introduction

Primary data

Santos⁵⁰ (2013)	Brazil (Sao Paulo, SP)	Case series including years before and after vaccine introduction	Prospective data collection at one university hospital that attends a population of approximately 408,000 inhabitants	Invasive pneumococcal disease	Number of cases/1,000 hospital admissions; antibiotic resistance and serotype distribution	Decrease in invasive pneumococcal disease cases among children under 2 years of age and decrease in vaccine serotypes after vaccine introduction
Parra³⁸ (2013)	Colombia	Case series on invasive pneumococcal disease and two transversal studies (before and after vaccine introduction) on nasopharyngeal carriage. Limitations: short observation period after vaccine introduction; children's vaccination status unavailable	Laboratory surveillance (SIREVA II) data on invasive pneumococcal disease and primary data collection on nasopharyngeal carriage	Invasive pneumococcal disease and nasopharyngeal carriage serotype distribution	Serotype distribution	Decrease in vaccine serotypes and increase in non-vaccine serotypes in invasive pneumococcal disease isolates after vaccine introduction

	Advantages	Limitations
Study design

Ecological	Relatively simple and less expensive Allows assessment of the vaccination program in a general population	Cannot establish causal relationships It is important to consider adjustment for secular trends and to have a control group (other areas without vaccination programs or other diseases)
Cohort	Provides the best information about causal relationships	Demands more time and resources
Descriptive and case series	Simplest study designs Can detect changes in types of rotavirus and pneumococcus after the introduction of vaccine programs	Cannot measure prevalence or incidence due to the lack of a well-defined population at risk. Give little information about temporal changes in the frequency of diseases

Data sources

Health information system databases	Broad coverage, lower costs, easy access to data and longitudinal follow-up	Lack of standardization in data collection and limitations in completeness and reliability of the available data, database continuity, coverage, representativeness, and sustainability
Sentinel-based and laboratory-based surveillance systems	Availability of unpublished data	Information on the catchment population frequently unavailable. Data not generalizable for the entire population. Variable coverage
Local secondary data (medical records of a single hospital)	Timeliness, low costs, and availability	Lack of standardization; data not generalizable to the entire population
Primary data	May answer specific research objectives More precision and reliability	Small sample size Not generalizable Expensive Sustainability

Clinical syndrome

All-cause diarrhea	Does not require specific laboratory tests. May be more valuable to decision makers	Less precision for vaccine effect on rotavirus disease
Rotavirus-related diarrhea	More specific and precise	May underestimate the true burden of disease and the global impact of vaccination programs
Pneumonia	More frequent	Challenging and variable definition and diagnosis
Invasive pneumococcal disease	More severe and of more precise diagnosis	Diagnosis requires the isolation of S. pneumonia, and laboratory tests are not uniformly performed
Meningitis	More severe, of more precise diagnosis and has more information available since it is a notifiable disease	Less frequent

Outcomes of interest

Hospitalization rate	Availability of data	Changes in diagnosis coding may affect estimates. Influenced by availability of beds, hospital admission policies and social factors. Unsuitable for clinical syndromes that are mostly treated in outpatient care such as otitis media
Mortality rate	More reliable than morbidity data	Measures only results of severe clinical syndromes; thus, changes in less severe conditions will not be identified. Difficulty in discriminating effects of changes in the incidence or treatment of conditions

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E-mail: revsp@usp.br

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[1] Correspondence
: Ana M C Sartori. Instituto Central do Hospital das Clínicas. Av. Dr. Enéas de Carvalho Aguiar, 255 4º andar, sala 4028 05403-010 São Paulo, SP, Brasil. E-mail: ana.sartori@hc.fm.usp.br