ABSTRACT:

Objective:

To analyze the temporal trend of vaccination coverage for hepatitis A, measles, mumps and rubella, and varicella in a Brazilian state from 2014 to 2020.

Methods:

An ecological, time-series study that considered data from 853 municipalities in the state of Minas Gerais that compose the 14 regions of the state, these being the territorial units of analysis. Records of applied doses of hepatitis A, measles, mumps and rubella, and varicella vaccines registered in the Brazilian Immunization Information System were analyzed. Trends were estimated by Prais-Winsten regression and 95% confidence intervals of measures of variation were calculated.

Results:

Low vaccine coverage of hepatitis A, measles, mumps and rubella, and varicella was identified. Coverages above 95% were observed only in 2015 for the vaccine against hepatitis A (98.8%) and, in 2016, for varicella (98.4%). The measles, mumps and rubella vaccine showed coverage of less than 95% in all analyzed years. Decreases of 13.6 and 4.3% between the years 2019 and 2020 were identified for the measles, mumps and rubella, and hepatitis A vaccines, respectively. There was a decreasing trend in hepatitis A vaccination coverage in the South (p=0.041), East (p=0.030), and North (p=0.045) regions; and for the measles, mumps and rubella in Jequitinhonha Valley (p=0.002), East (p=0.004), and North (p=0.024) regions. Increasing coverage was observed only for varicella in eight regions of the state.

Conclusions:

The data point to heterogeneity in the temporal behavior of vaccination coverage in Minas Gerais. The downward trend in some regions causes concern about the possibility of resurgence of diseases, such as measles, which until then had been controlled.

Keywords:
Immunization programs; Vaccination coverage; Health information systems; Health evaluation; Ecological studies

INTRODUCTION

Achieving coverage goals for all vaccines in the national immunization schedule by 2020 was proposed by the Global Vaccine Action Plan 2011-2020. However, less than two-thirds of the countries attained the proposed goal, as illustrated by the third dose of the DTaP (diphtheria, tetanus, and acellular pertussis) vaccine, with 66% coverage¹1. Peck M, Gacic-Dobo M, Diallo MS, Nedelec Y, Sodha SV, Wallace AS. Global routine vaccination coverage, 2018. MMWR Morb Mortal Wkly Rep 2019; 68(42): 937-42. https://doi.org/10.15585/mmwr.mm6842a1
https://doi.org/https://doi.org/10.15585... . In Brazil, a recent study showed temporal trends of reduction in vaccination coverage in the five Brazilian regions in the period from 2006 to 2016²2. Arroyo LH, Ramos ACV, Yamamura M, Weiller TH, Crispim JA, Cartagena-Ramos D, et al. Áreas com queda da cobertura vacinal para BCG, poliomielite e tríplice viral no Brasil (2006-2016): mapas da heterogeneidade regional. Cad Saúde Pública 2020; 36(4): e00015619. https://doi.org/10.1590/0102-311x00015619
https://doi.org/https://doi.org/10.1590/... . The circulation of fake news about immunobiologicals³3. Frugoli AG, Prado RS, Silva TMR, Matozinhos FP, Trapé CA, Lachtim SAF. Fake news sobre vacinas: uma análise sob o modelo dos 3Cs da Organização Mundial da Saúde. Rev Esc Enferm USP 2021; 55: e03736. https://doi.org/10.1590/S1980-220X2020028303736
https://doi.org/https://doi.org/10.1590/... , vaccine hesitancy⁴4. Aps LRMM, Piantola MAF, Pereira SA, Castro JT, Santos FAO, Ferreira LCS. Eventos adversos de vacinas e as consequências da não vacinação: uma revisão crítica. Rev Saude Publica. 2018; 52: 40. http://doi.org/10.11606/S1518-8787.2018052000384
https://doi.org/http://doi.org/10.11606/... and, more recently, the pandemic caused by COVID-19⁵5. Lassi ZS, Naseem R, Salam RA, Siddiqui F, Das JK. The impact of the COVID-19 pandemic on immunization campaigns and programs: a systematic review. Int J Environ Res Public Health 2021; 18(3): 988. https://doi.org/10.3390/ijerph18030988
https://doi.org/https://doi.org/10.3390/... are some of the determinants pointed out in the literature. Nonetheless, the decline in immunization is heterogeneous among Brazilian municipalities²2. Arroyo LH, Ramos ACV, Yamamura M, Weiller TH, Crispim JA, Cartagena-Ramos D, et al. Áreas com queda da cobertura vacinal para BCG, poliomielite e tríplice viral no Brasil (2006-2016): mapas da heterogeneidade regional. Cad Saúde Pública 2020; 36(4): e00015619. https://doi.org/10.1590/0102-311x00015619
https://doi.org/https://doi.org/10.1590/... and may reflect social inequalities⁶6. Buffarini R, Barros FC, Silveira MF. Vaccine coverage within the first year of life and associated factors with incomplete immunization in a Brazilian birth cohort. Arch Public Health 2020; 78: 21. https://doi.org/10.1186/s13690-020-00403-4
https://doi.org/https://doi.org/10.1186/... and inequities related to access to health services⁷7. Duarte DC, Oliveira VC, Guimarães EAA, Viegas SMF. Acesso à vacinação na Atenção Primária na voz do usuário: sentidos e sentimentos frente ao atendimento. Esc Anna Nery 2019; 23(1): e20180250. https://doi.org/10.1590/2177-9465-EAN-2018-0250
https://doi.org/https://doi.org/10.1590/... .

Currently, the Immunization Agenda 2030 global strategy envisions a world where people, of all ages and from everywhere, fully benefit from vaccines offered to improve the health and well-being of the population. This intervention proposes to maintain the positive results achieved in vaccination and recover the losses caused by COVID-19⁸8. World Health Organization. Implementing the immunization agenda 2030: a framework for action through coordinated planning, monitoring & evaluation, ownership & accountability, and communications & advocacy. Genebra: World Health Organization [Internet]. 2021 [acessado em 18 out. 2021]. Disponível em: Disponível em: https://cdn.who.int/media/docs/default-source/immunization/strategy/ia2030/ia2030_frameworkforactionv04.pdf?sfvrsn=e5374082_1&download=true
https://cdn.who.int/media/docs/default-s... .

The most significant impacts of non-vaccination have been morbidity and mortality from serious infections that disproportionately affect children⁹9. Rodrigues CMC, Plotkin SA. Impact of vaccines; health, economic and social perspectives. Front Microbiol 2020; 11: 1526. https://doi.org/10.3389/fmicb.2020.01526
https://doi.org/https://doi.org/10.3389/... . Among the vaccines offered to this group, there is a concern about the drop in coverage observed in several countries of the vaccination against measles, mumps, rubella, and varicella, highly contagious diseases with several associated clinical complications¹⁰10. Di Pietrantonj CD, Rivetti A, Marchione P, Debalini MG, Demicheli V. Vaccines for measles, mumps, rubella, and varicella in children. Cochrane Database Syst Rev. 2020; 4(4): CD004407. https://doi.org/10.1002/14651858.CD004407.pub4
https://doi.org/https://doi.org/10.1002/... .

The introduction of the live-attenuated vaccine against varicella is a preventive strategy adopted in several countries. The schedules vary in terms of the number of doses, the combination with other vaccines, and the age of immunization¹¹11. Hirose M, Gilio AE, Ferronato AE, Ragazzi SLB. The impact of varicella vaccination on varicella-related hospitalization rates: global data review. Rev Paul Pediatr 2016; 34(3): 359-66. https://doi.org/10.1016/j.rpped.2015.12.006
https://doi.org/https://doi.org/10.1016/... . The efficacy of a single-dose varicella vaccine in preventing infection and moderate/severe disease is estimated to be 81 and 98%, respectively¹²12. Marin M, Marti M, Kambhampati A, Jeram SM, Seward JF. Global varicella vaccine effectiveness: a meta-analysis. Pediatrics 2016; 137(3): e20153741. https://doi.org/10.1542/peds.2015-3741
https://doi.org/https://doi.org/10.1542/... . However, its coverage had an estimated average of 78% in 2016 in Brazil, and since then a decrease has been observed, reaching 34.3% in 2019¹³13. Manetti CL, Fernandes B, Oliveira DK, Banovski DC, Araújo SP, Brusque CEP, et al. Varicela grave: an analysis of compulsory notifications, Brazil 2012 to 2019. RSD 2021; 10(2): e7510212026. https://doi.org/10.33448/rsd-v10i2.12026
https://doi.org/https://doi.org/10.33448... .

Another vaccine that is part of the national schedule is the measles, mumps, and rubella (MMR) vaccine, which prevents the occurrence of these diseases. Estimates of the effectiveness of the MMR vaccine are 99% in preventing measles after a second dose, more than 95% in preventing mumps, and 90% in preventing rubella after a single dose¹⁴14. Bailey A, Sapra A. MMR Vaccine. Treasure Island (FL): StatPearls Publishing; 2022.. Nevertheless, a reduction of 2.7% per year in its coverage was observed in Brazil in the period from 2006 to 2016²2. Arroyo LH, Ramos ACV, Yamamura M, Weiller TH, Crispim JA, Cartagena-Ramos D, et al. Áreas com queda da cobertura vacinal para BCG, poliomielite e tríplice viral no Brasil (2006-2016): mapas da heterogeneidade regional. Cad Saúde Pública 2020; 36(4): e00015619. https://doi.org/10.1590/0102-311x00015619
https://doi.org/https://doi.org/10.1590/... .

In addition, the hepatitis A vaccine also had a decrease in coverage in all Brazilian regions after 2015, ranging between 60.0 and 82.0% among Brazilian municipalities¹⁵15. Brito WI, Souto FJD. Vacinação universal contra hepatite A no Brasil: análise da cobertura vacinal e da incidência cinco anos após a implantação do programa. Rev Bras Epidemiol 2020; 23: E200073. https://doi.org/10.1590/1980-549720200073
https://doi.org/https://doi.org/10.1590/... . Although hepatitis A has mild clinical manifestations in childhood, the World Health Organization (WHO) estimates more than 7,000 deaths per year worldwide¹⁶16. World Health Organization. Hepatitis A. [Internet]. 2022 [acessado em 10 fev. 2022]. Disponível em: Disponível em: https://www.who.int/news-room/fact-sheets/detail/hepatitis-a
https://www.who.int/news-room/fact-sheet... .

Considering the variations in vaccination coverage between countries and within Brazil, it is opportune to analyze the territory in spatial units with a higher level of spatial disaggregation. The state of Minas Gerais, the second most populous in Brazil¹⁷17. Instituto Brasileiro de Geografia e Estatística. Cidades e Estados [Internet]. 2020 [acessado em 18 out. 2021]. Disponível em: Disponível em: https://www.ibge.gov.br/cidades-e-estados/mg.html
https://www.ibge.gov.br/cidades-e-estado... , has recently faced epidemics and outbreaks of vaccine-preventable diseases18.

Therefore, considering the low childhood vaccination coverage and its already visible consequences, efforts to propose a strategic planning consistent with the characteristics of each Brazilian region for assertive decision-making are justified. Thus, the objective of this study was to analyze the temporal trend of vaccination coverage for hepatitis A, MMR, and varicella in a Brazilian state from 2014 to 2020.

METHODS

This is an ecological, time-series study whose location is the state of Minas Gerais, the second-most populous state in Brazil and the fourth in territorial extension¹⁷17. Instituto Brasileiro de Geografia e Estatística. Cidades e Estados [Internet]. 2020 [acessado em 18 out. 2021]. Disponível em: Disponível em: https://www.ibge.gov.br/cidades-e-estados/mg.html
https://www.ibge.gov.br/cidades-e-estado... . The 14 regions of the state were used as territorial units of analysis: South, South-Central, Central, Jequitinhonha Valley, West, East, Aço Valley, Southeast, North, Northwest, Leste do Sul, Northeast, Triângulo do Sul, and Triângulo do Norte¹⁷17. Instituto Brasileiro de Geografia e Estatística. Cidades e Estados [Internet]. 2020 [acessado em 18 out. 2021]. Disponível em: Disponível em: https://www.ibge.gov.br/cidades-e-estados/mg.html
https://www.ibge.gov.br/cidades-e-estado... .

The study population consisted of children living in the 853 municipalities of Minas Gerais who had vaccination records for immunobiological agents offered by the National Immunization Program (Plano Nacional de Imunizações - PNI) in the PNI Information System (SI-PNI). Data from vaccine doses administered for the prevention of hepatitis A (single dose at 15 months of age), MMR (second dose at 15 months of age), and varicella (first dose at 15 months of age) in the period from 2014 (deadline for implementing the SI-PNI in Brazil) to 2020 were used. The coverage goal recommended by PNI for all these vaccines is 95%¹⁹19. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Programa Nacional de Imunizações. Coberturas vacinais no Brasil. Período: 2010-2014 [Internet]. 2015 [acessado em 10 out. 2021]. Disponível em: Disponível em: https://siteal.iiep.unesco.org/sites/default/files/sit_accion_files/br_5113.pdf
https://siteal.iiep.unesco.org/sites/def... .

It is worth highlighting that the measles, mumps, rubella, and varicella vaccine (MMRV) was not analyzed, considering that, according to information from the PNI Coordination of Minas Gerais, there were gaps in its supply to the municipal health service during the study period.

Data on routine childhood vaccinations were extracted from the SI-PNI provided by the Minas Gerais State Department of Health, and data on vaccine target populations per municipality were obtained through access to the Brazilian Health Informatics Department, of the Brazilian Unified Health System (SUS)/Live Birth Information System. Microsoft Office Excel software (2016) was used to structure the vaccination coverage indicator. This indicator presents, in the numerator, the number of children vaccinated considering the complete vaccination schedule and, in the denominator, the target population for the vaccine. Multiplication factor: 100¹⁹19. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Programa Nacional de Imunizações. Coberturas vacinais no Brasil. Período: 2010-2014 [Internet]. 2015 [acessado em 10 out. 2021]. Disponível em: Disponível em: https://siteal.iiep.unesco.org/sites/default/files/sit_accion_files/br_5113.pdf
https://siteal.iiep.unesco.org/sites/def... .

For trend analysis, the Stata software (version 12) and the Prais-Winsten linear regression model were used, in which the independent variable (x) was the year (2014 to 2020) and the dependent variable (y), the vaccination coverage. This model is indicated to correct serial correlation in time series and it allows analyzing trends with seven or more points²⁰20. Antunes JLF, Cardoso MRA. Uso da análise de séries temporais em estudos epidemiológicos. Epidemiol Serv Saúde 2015; 24(3): 565-76. https://doi.org/10.5123/S1679-49742015000300024
https://doi.org/https://doi.org/10.5123/... .

Initially, the logarithmic transformation of the y values was performed to reduce the heterogeneity of the variance of the residuals of the regression analysis. Subsequently, the application of the Prais-Winsten model was carried out. To identify the average annual percent change (APC), the values of the b1 coefficient corresponding to each of the indicators were applied to the following formula: APC=-1+10 b1 *100%. Finally, the 95% confidence intervals (CI) of the variation measures were calculated by applying the following formulas: Minimum 95%CI= -1+10 b1-t*e *100%; maximum 95%CI= -1+10 b1+t*e *100%.

The values of the b1 coefficient (beta) and e (standard error) were generated by the statistical analysis program. The t refers to the Student’s t-test and corresponds to six degrees of freedom (2.447), which indicates the seven years of analysis (2014-2020), with a confidence level of 95%. The interpretation of the results was performed as follows: upward trend, when the average annual percent change was significantly positive; downward trend, when the average annual percent change was significantly negative; and stationary, when accepting the null hypothesis that there is no significant difference between the value of the variation and zero²⁰20. Antunes JLF, Cardoso MRA. Uso da análise de séries temporais em estudos epidemiológicos. Epidemiol Serv Saúde 2015; 24(3): 565-76. https://doi.org/10.5123/S1679-49742015000300024
https://doi.org/https://doi.org/10.5123/... .

The present study uses data from the public domain of open access, for which there is no identification of the individuals participating in the investigation; therefore, there is no need for consideration on the part of the Research Ethics Committee.

RESULTS

Throughout the analyzed period, the state of Minas Gerais presented fluctuations in the vaccination coverage of hepatitis A, MMR, and varicella. Coverages above 95% were observed only in 2015 for the vaccine against hepatitis A (98.8%) and, in 2016, for varicella (98.4%). The MMR vaccine had coverage of less than 95% in all years. Decreases of 13.6 and 4.3% between the years 2019 and 2020 were identified for the MMR and hepatitis A vaccines, respectively (Figure 1).

The graph was the first step in understanding the processes underlying temporally ordered measures. Subsequently, the values, established for each region of the state, demonstrate an even more emblematic result. In Table 1 the predominance of the stationary trend, by region, for hepatitis A and MMR vaccines can be observed. The downward trend in hepatitis A vaccination coverage stands out in the South (p=0.041), East (p=0.030), and North (p=0.045) regions; and for the MMR vaccine, in Jequitinhonha Valley (p=0.002), East (p=0.004), and North (p=0.024) regions. The annual percentage change in the downward trend of vaccination coverage was between -5.21 and -8.43% in the period from 2014 to 2020. Conversely, the upward trend was only observed for the varicella vaccine in most regions, with an annual percentage change from 29.15 to 49.57%.

DISCUSSION

The average vaccination coverage in Minas Gerais, for the three analyzed vaccines, did not achieve the 95% coverage goal as recommended by PNI¹⁹19. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Programa Nacional de Imunizações. Coberturas vacinais no Brasil. Período: 2010-2014 [Internet]. 2015 [acessado em 10 out. 2021]. Disponível em: Disponível em: https://siteal.iiep.unesco.org/sites/default/files/sit_accion_files/br_5113.pdf
https://siteal.iiep.unesco.org/sites/def... . The study findings corroborate records of recent low coverage in other countries²¹21. Lo Vecchio A, Cambriglia MD, Fedele MC, Basile FW, Chiatto F, Del Giudice MM, et al. Determinants of low measles vaccination coverage in children living in an endemic area. Eur J Pediatr 2019; 178(2): 243-51. https://doi.org/10.1007/s00431-018-3289-5
https://doi.org/https://doi.org/10.1007/... ^,2222. Tesfaye TD, Temesgen WA, Kasa AS. Vaccination coverage and associated factors among children aged 12 - 23 months in Northwest Ethiopia. Hum Vaccin Immunother 2018; 14(10): 2348-354. https://doi.org/10.1080/21645515.2018.1502528
https://doi.org/https://doi.org/10.1080/... .

Around 14 million children worldwide did not receive vital vaccines, such as the measles vaccine, which resulted in outbreaks recorded in Venezuela, in 2017; Madagascar, the Philippines, and Brazil between 2018 and 2019²³23. Fundo das Nações Unidas para a Infância. Surto global de sarampo, uma ameaça crescente para crianças [Internet]. 2019 [acessado em 10 fev. 2022]. Disponível em: Disponível em: https://www.unicef.org/brazil/comunicados-de-imprensa/surto-global-de-sarampo-uma-ameaca-crescente-para-criancas
https://www.unicef.org/brazil/comunicado... ^,2424. Organização Pan-Americana da Saúde. Dados preliminares da OMS apontam que casos de sarampo em 2019 quase triplicaram em relação ao ano passado [Internet]. 2019 [acessado em 10 fev. 2022]. Disponível em: Disponível em: https://www.paho.org/pt/noticias/12-8-2019-dados-preliminares-da-oms-apontam-que-casos-sarampo-em-2019-quase-triplicaram-em
https://www.paho.org/pt/noticias/12-8-20... . In Ukraine, in 2016, only 42% of newborns and 31% of children up to six years of age were vaccinated against measles²⁵25. Wadman M. Measles cases have tripled in Europe, fueled by Ukrainian outbreak. Science [Internet]. 2019 [acessado em 10 fev. 2022]. Disponível em: Disponível em: https://www.science.org/content/article/measles-cases-have-tripled-europe-fueled-ukrainian-outbreak
https://www.science.org/content/article/... . In England, there was a 19.8% drop in the applied doses of the MMR vaccine between 2019 and 2020. In the United States of America, coverage for hepatitis A was below the Healthy People 2020 goal of 85%, reaching about 76.6% among children born in 2015-2016²⁷27. Hill HA, Singleton JA, Yankey D, Elam-Evans LD, Pingali SC, Kang Y. Vaccination coverage by age 24 months among children born in 2015 and 2016 - National Immunization Survey-Child, United States, 2016-2018. MMWR Morb Mortal Wkly Rep 2019; 68(41): 913-18. https://doi.org/10.15585/mmwr.mm6841e2
https://doi.org/https://doi.org/10.15585... .

According to official records from the Brazilian Ministry of Health, the decrease in vaccination coverage in Brazil was demarcated from 2016 onwards, with about 10 to 20 percentage points²⁸28. Brasil. Ministério da Saúde. Programa Nacional de Imunização. Sistema de Informação do Programa Nacional de Imunizações - SI-PNI. Brasília: Ministério da Saúde [Internet]. 2018 [citado em 10 set. 2021]. Disponível em: Disponível em: http://sipni.datasus.gov.br/si-pni- web/faces/inicio.jsf
http://sipni.datasus.gov.br/si-pni- web/... . A reduction was also observed in the present investigation for MMR and hepatitis A coverage in 2020.

With the COVID-19 pandemic, it is estimated that the probability of a child up to five years of age receiving all vaccines is 20%²⁹29. Bonani LO, Souza GS. A importância da vacinação infantil para a erradicação do Sarampo. Brazilian Journal of Health Review 2021; 4(3): 9731-5. https://doi.org/10.34119/bjhrv4n3-011
https://doi.org/https://doi.org/10.34119... . Attendance at health centers dramatically decreased this year, including for childhood vaccinations, due to social distancing measures to mitigate the transmission of the Sars-CoV-2 virus³⁰30. Abbas K, Procter SR, van Zandvoort K, Clark A, Funk S, Mengistu T, et al. Routine childhood immunization during the COVID-19 pandemic in Africa: a benefit-risk analysis of health benefits versus excess risk of SARS-CoV-2 infection. Lancet Global Health 2020; 8(10): e1264-e1272. https://doi.org/10.1016/S2214-109X(20)30308-9
https://doi.org/https://doi.org/10.1016/... .

Moreover, the growing anti-vaccine movement, intensified with the vaccination against COVID-19, the circulation of fake news about immunobiological agents, and vaccine hesitancy are some of the determinants pointed out in the literature that accentuate the drops in vaccination coverage, already verified since 2016³3. Frugoli AG, Prado RS, Silva TMR, Matozinhos FP, Trapé CA, Lachtim SAF. Fake news sobre vacinas: uma análise sob o modelo dos 3Cs da Organização Mundial da Saúde. Rev Esc Enferm USP 2021; 55: e03736. https://doi.org/10.1590/S1980-220X2020028303736
https://doi.org/https://doi.org/10.1590/... ^,3131. Sato APS. What is the importance of vaccine hesitancy in the drop of vaccination coverage in Brazil? Rev Saude Publica 2018; 52: 96. https://doi.org/10.11606/S1518-8787.2018052001199
https://doi.org/https://doi.org/10.11606... ^,3232. Santana E, Braz CLM, Vital T, Gurgel H. Cobertura vacinal da poliomielite na região Nordeste do Brasil no primeiro ano de pandemia por Covid-19. Estrabão 2022; 3: 1-15. https://doi.org/10.53455/re.v3i.29
https://doi.org/https://doi.org/10.53455... .

However, this decline was not observed for the varicella vaccine, applied together with the MMR vaccine at 15 months of age (replacing the MMRV one), considering that this vaccine has not been available in the state of Minas Gerais since 2017³³33. Brasil. Ministério da Saúde. Nota Informativa no 17-SEI/2017-CGPNI/DEVIT/SVS/MS. Informa acerca da situação da distribuição de imunobiológicos na rotina do mês de julho/2017. [Internet]. 2017 [acessado em 18 out. 2021]. Disponível em: Disponível em: http://www.mt.gov.br/documents/21013/5691628/Nota+do+Ministério+da+Saúde/dbebb981-0f18-4fe8-9501-a574f46558ed
http://www.mt.gov.br/documents/21013/569... . It is assumed that some professionals are registering the second dose of the MMR vaccine instead of the MMRV vaccine. This assumption points to underestimated coverage of this vaccine, which is consistent with the findings of the present study, in which the MMR vaccine was the one with the greatest decrease in vaccination coverage.

Furthermore, it is worth mentioning the change in the SI-PNI that took place in 2014. The system, which used to be fed according to the applied doses, changed to the nominal record. This change posed difficulties because, in addition to the equipment and all the necessary logistics, it was necessary to have trained personnel to feed the system³⁴34. Cruz A. A queda da imunização no Brasil. Saúde em Foco. Revista Consensus 2017; 25: 20-9. [acessado em 10 out. 2021]. Disponível em: Disponível em: https://portal.fiocruz.br/sites/portal.fiocruz.br/files/documentos/revistaconsensus_25_a_queda_da_imunizacao.pdf
https://portal.fiocruz.br/sites/portal.f... ^,3535. Silva BS, Guimarães EAA, Oliveira VC, Cavalcante RB, Pinheiro MMK, Gontijo TL, et al. National Immunization Program Information System: implementation context assessment. BMC Health Serv Res 2020; 20(1): 333. https://doi.org/10.1186/s12913-020-05175-9
https://doi.org/https://doi.org/10.1186/... . Currently, the registration of administered doses is made in the Citizen’s Electronic Health Record (Prontuário Eletrônico do Cidadão), a software developed based on the e-SUS Primary Care strategy³⁶36. Brasil. Ministério da Saúde. Secretaria de Atenção Primária à Saúde. e-SUS Atenção básica: manual do sistema com prontuário eletrônico do cidadão PEC - Versão 3.2. Brasília: Ministério as Saúde; 2020. Disponível em: http://189.28.128.100/dab/docs/portaldab/documentos/esus/Manual_Pec_3_2.pdf
http://189.28.128.100/dab/docs/portaldab... . These factors may have resulted in lower registration of the administered doses, making data on vaccination coverage inaccurate in some places¹⁵15. Brito WI, Souto FJD. Vacinação universal contra hepatite A no Brasil: análise da cobertura vacinal e da incidência cinco anos após a implantação do programa. Rev Bras Epidemiol 2020; 23: E200073. https://doi.org/10.1590/1980-549720200073
https://doi.org/https://doi.org/10.1590/... .

Seeking to reduce the distortions of analysis of places with great territorial extension, the analyses of this study were carried out per region, which allowed the identification of important heterogeneities within the state of Minas Gerais. In addition, more than delimiting geographic differences, it was possible to diagnose the rate of increase, decrease, or stabilization of the coverage of an area over time through regression models.

The North, East, South, and Jequitinhonha Valley regions stand out, which had downward trends for MMR and/or hepatitis A vaccines. These areas should be considered the most at risk for the transmission of measles, mumps, rubella, and hepatitis A, precisely because of the low vaccination coverage.

Despite the decrease in the incidence of hepatitis A, vaccination coverage in the year of its implementation was low across the country, suggesting the impact of improvements in health conditions³⁷37. Migueres M, Lhomme S, Izopet J. Hepatitis A: epidemiology, high-risk groups, prevention and research on antiviral treatment. Viruses 2021; 13(10): 1900. https://doi.org/10.3390/v13101900
https://doi.org/https://doi.org/10.3390/... or even underreporting of the disease¹⁵15. Brito WI, Souto FJD. Vacinação universal contra hepatite A no Brasil: análise da cobertura vacinal e da incidência cinco anos após a implantação do programa. Rev Bras Epidemiol 2020; 23: E200073. https://doi.org/10.1590/1980-549720200073
https://doi.org/https://doi.org/10.1590/... . Moreover, the lack of the hepatitis A vaccine, which occurred from the beginning of 2016 to the end of 2017, also contributed to the reduction of vaccination coverage¹⁵15. Brito WI, Souto FJD. Vacinação universal contra hepatite A no Brasil: análise da cobertura vacinal e da incidência cinco anos após a implantação do programa. Rev Bras Epidemiol 2020; 23: E200073. https://doi.org/10.1590/1980-549720200073
https://doi.org/https://doi.org/10.1590/... . Nevertheless, the shortage of hepatitis A vaccine does not seem to be associated with the low vaccination coverage in the state of Minas Gerais, as the downward trend was only restricted to three regions of the state, and the lack of the vaccine affected the entire national territory.

The childhood vaccines recommended worldwide are based on the scientific principle of their preventive effect³⁸38. La Torre G, Saulle R, Unim B, Megiollaro A, Barbato A, Mannocci A, et al. The effectiveness of measles-mumps-rubella (MMR) vaccination in the prevention of pediatric hospitalizations for targeted and untargeted infections: a retrospective cohort study. Hum Vaccin Immunother 2017; 13(8): 1879-83. https://doi.org/10.1080/21645515.2017.1330733
https://doi.org/https://doi.org/10.1080/... . Measles, mumps, and rubella are other highly contagious vaccine-preventable childhood diseases. Although not always serious, these diseases can cause disabilities (such as deafness), complications, and death¹⁰10. Di Pietrantonj CD, Rivetti A, Marchione P, Debalini MG, Demicheli V. Vaccines for measles, mumps, rubella, and varicella in children. Cochrane Database Syst Rev. 2020; 4(4): CD004407. https://doi.org/10.1002/14651858.CD004407.pub4
https://doi.org/https://doi.org/10.1002/... .

In Minas Gerais, the North, East, and Jequitinhonha Valley regions have high levels of poverty³⁹39. Minas Gerais. Secretaria de Estado de Planejamento e Gestão. Plano Mineiro de Desenvolvimento Integrado 2016 a 2027. Perfis Territoriais [Internet]. 2015 [acessado em 14 mar. 2022]. Disponível em: Disponível em: https://www.mg.gov.br/sites/default/files/transicao-governamental/Catálogo%20PMDI%20Volume%201.pdf
https://www.mg.gov.br/sites/default/file... , which could explain the drops in vaccination coverage for MMR and/or hepatitis A. However, this phenomenon should be cautiously analyzed. Low coverage is also verified among the population strata with greater purchasing power⁴⁰40. Olive JK, Hotez PJ, Damania A, Nolan MS. The state of the antivaccine movement in the United States: a focused examination of nonmedical exemptions in states and counties. PLoS Med 2018; 15(6): e1002578. https://doi.org/10.1371/journal.pmed.1002578
https://doi.org/https://doi.org/10.1371/... .

Other important elements for the low vaccination coverage are the shortage of vaccines³³33. Brasil. Ministério da Saúde. Nota Informativa no 17-SEI/2017-CGPNI/DEVIT/SVS/MS. Informa acerca da situação da distribuição de imunobiológicos na rotina do mês de julho/2017. [Internet]. 2017 [acessado em 18 out. 2021]. Disponível em: Disponível em: http://www.mt.gov.br/documents/21013/5691628/Nota+do+Ministério+da+Saúde/dbebb981-0f18-4fe8-9501-a574f46558ed
http://www.mt.gov.br/documents/21013/569... and the difficulty in accessing healthcare services (distance between the residence and the health center, lack of public transport, reduced service hours of the health center, deficiency in the continuing education of healthcare professionals)⁷7. Duarte DC, Oliveira VC, Guimarães EAA, Viegas SMF. Acesso à vacinação na Atenção Primária na voz do usuário: sentidos e sentimentos frente ao atendimento. Esc Anna Nery 2019; 23(1): e20180250. https://doi.org/10.1590/2177-9465-EAN-2018-0250
https://doi.org/https://doi.org/10.1590/... .

Thus, promoting intersectoral involvement, such as awareness-raising actions in churches and schools⁴⁰40. Olive JK, Hotez PJ, Damania A, Nolan MS. The state of the antivaccine movement in the United States: a focused examination of nonmedical exemptions in states and counties. PLoS Med 2018; 15(6): e1002578. https://doi.org/10.1371/journal.pmed.1002578
https://doi.org/https://doi.org/10.1371/... , monitoring coverage through periodic household surveys, and expanding the supply of vaccines to bring them closer to communities⁴¹41. Ryman TK, Dietz V, Cairns KL. Too little but not too late: results of a literature review to improve routine immunization programs in developing countries. BMC Health Services Research 2008; 8: 134. https://doi.org/10.1186/1472-6963-8-134
https://doi.org/https://doi.org/10.1186/... , are some key interventions.

The low vaccination coverage in some regions of Minas Gerais is of great concern, considering the possibility of the resurgence of diseases hitherto eliminated or controlled. This scenario can be well illustrated by recalling the measles outbreak that occurred in 2018 in the states of Roraima and Amazonas⁴²42. Elidio GA, França GVA, Pacheco FC, Ferreira MM, Pinheiro JS, Campos EN, et al. Measles outbreak: preliminary report on a case series of the first 8,070 suspected cases, Manaus, Amazonas state, Brazil, February to November 2018. Euro Surveill 2019; 24(2): 1800663. https://doi.org/10.2807/1560-7917.ES.2019.24.2.1800663
https://doi.org/https://doi.org/10.2807/... .

In this sense, it is worth mentioning that, even in countries with effective immunization programs, such as Brazil, the advances achieved in previous years can be easily lost without constant monitoring²2. Arroyo LH, Ramos ACV, Yamamura M, Weiller TH, Crispim JA, Cartagena-Ramos D, et al. Áreas com queda da cobertura vacinal para BCG, poliomielite e tríplice viral no Brasil (2006-2016): mapas da heterogeneidade regional. Cad Saúde Pública 2020; 36(4): e00015619. https://doi.org/10.1590/0102-311x00015619
https://doi.org/https://doi.org/10.1590/... . Access to immunization must be universal, regardless of geographic location; hence, policies and programs should take more effective measures to reduce inequities in vaccination. Equity must remain as a strong motivator aspect to ensure that everyone enjoys the benefits of immunization, including the most disadvantaged and marginalized populations⁸8. World Health Organization. Implementing the immunization agenda 2030: a framework for action through coordinated planning, monitoring & evaluation, ownership & accountability, and communications & advocacy. Genebra: World Health Organization [Internet]. 2021 [acessado em 18 out. 2021]. Disponível em: Disponível em: https://cdn.who.int/media/docs/default-source/immunization/strategy/ia2030/ia2030_frameworkforactionv04.pdf?sfvrsn=e5374082_1&download=true
https://cdn.who.int/media/docs/default-s... .

Among the limitations of this study, it is noteworthy that the use of secondary data can often result in inconsistencies in the estimated indicator (vaccination coverage), but, despite this, the choice of this type of source reduces operational costs and does not make the performance of analyses unfeasible. To minimize this limitation, a database consistency analysis was conducted.

The study presents evidence on reduction in the vaccination coverage of hepatitis A in the South, East, and North regions; and of MMR in the Jequitinhonha Valley, East, and North regions of the state of Minas Gerais. Conversely, increasing coverage was observed only for varicella in eight regions of the state. Therefore, it was verified that the heterogeneity in the temporal behavior of vaccination coverage requires strategic planning consistent with the characteristics of each location.

For future studies, it would be opportune to understand the factors associated with the temporal behaviors identified, including the development of field research. In addition, the vaccination records of the SI-PNI require attention and must be continuously monitored to improve the quality of the information used in services and research.

ACKNOWLEDGMENTS

The authors would like to thank the support received from Universidade Federal de São João Del Rei, Minas Gerais State Department of Health, Coordination for the Improvement of Higher Education Personnel (CAPES - code 001), and Minas Gerais Research Funding Foundation.

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