Elsevier

Vaccine

Volume 36, Issue 2, 4 January 2018, Pages 280-284
Vaccine

Early impact of universal varicella vaccination on childhood varicella and herpes zoster hospitalizations in Brazil

https://doi.org/10.1016/j.vaccine.2017.11.057Get rights and content

Highlights

  • VZV-related hospitalization decreased after MMRV introduction.

  • An indirect effect in unvaccinated children was not detected.

  • This data is an evidence of the health public impact of this varicella vaccine.

Abstract

Introduction

The Brazilian childhood National Immunization Program (NIP) introduced live and attenuated varicella vaccination in a single dose, combined as tetraviral vaccine, at 15 months of age in the whole country, during September to December of 2013. The aim of this study was to report trends in incidence of childhood hospital admissions related to varicella and zoster in Brazil from 2003 to 2016, including the first three years after vaccine introduction.

Methods

The number and incidence of hospital admission in patients aged less than 20 years in Brazilian public health system with an admission diagnosis of varicella and zoster from 2003 to 2016 were analyzed and pre (2003–2013) and post-vaccination periods (2014–2016) were compared. The data were obtained from DATASUS, a Brazilian government’s open-access public health database system, and analyzed adjusting for secular trend and seasonality if a statistically significant change was found.

Results

During the study period, 69,791 admissions due to varicella and herpes zoster occurred in the children younger than 20 years. After adjusting for seasonality, the incidence of hospitalizations decreased from 27.33 to 14.33 per 100000 per year, which corresponds to a reduction of 47.6% (95% confidence interval 18.19–77.04%, p < 0.001) in the vaccinated age group (1–4 years) in 2014–2016 compared to pre-vaccination period. The changes were not significant in the unvaccinated age groups.

Conclusion

The hospitalizations due to varicella and herpes zoster were decreased by half early after the introduction of a single dose of tetraviral vaccine in NIP in the vaccinated children. Further studies may assess duration and intensity of this effect, as well as the indirect effect in the unvaccinated age groups.

Introduction

Primary infection due to varicella-zoster virus (VZV), also known as chickenpox, is very common in children. It is a highly contagious illness, spreading through direct contact and aerosols, with a secondary attack index higher than 70% in unvaccinated groups [1]. Although it usually manifests as a mild and self-limited disease, complications such as pneumonitis, encephalitis, secondary bacterial infections and deaths can occur [2]. Morbimortality is higher among adults, as well as in immunocompromised patients. During childhood, those aged less than four years have a higher incidence of hospitalizations and death [3]. The incidence of varicella peaks in November in Brazil. The reported estimates show a mortality rate of 0.88/100000/year in infants younger than 12 months and 0.40/100000/year in children aged 1–4 years [3], [4].

The introduction of live, attenuated vaccination against varicella is a preventive strategy adopted in several countries. The schedules are variable regarding the number of doses (one or two), the combination with other vaccines and age of immunization [5]. The overall effectiveness of single dose varicella vaccine in preventing infection and severe disease is estimated to be 81 and 98%, respectively [6]. In a two doses schedule, the effectiveness against all forms of disease increases to more than 90%, with most of the data obtained from high-income countries, as United States of America, Australia, Germany, Italy, Spain and Canada [6], [7], [8], [9], [10], [11], [12].

In 2013, a tetraviral combined live and attenuated vaccine including measles, mumps, rubella and varicella (MMRV) was introduced in the Brazilian National Immunization Program (NIP), including all Brazilian states. The introduction occurred from September to December in children in a single dose regimen, at 15 months of age. The first dose of MMR (measles, mumps, and rubella) at one year of age, which was previously part of Brazilian NIP schedule, was also maintained. Both MMR and MMRV are being manufactured in Brazil, at Institute of Technology in Immunobiologicals (Bio-Manguinhos/Fiocruz), after a technology transfer from GlaxoSmithKline (GSK) [3], [5]. The estimated coverage of MMRV vaccination according to the Brazilian Ministry of Health from 2014 to 2016 was 60% [13]. Previously, varicella or MMRV vaccines were available only in private health system to a small subset of the Brazilian population and in a few municipalities [14].

The primary aim of this study was to assess the direct and indirect impacts of tetraviral vaccine by comparing the incidence of varicella and herpes zoster admissions in children before (2003–2013) and after (2014–2016) MMRV introduction. The description of deaths and costs due to VZV-related admission during the same period were the secondary aims.

Section snippets

Materials and methods

This observational study was based on the analysis of data on admissions and deaths due to varicella and herpes zoster. The data were obtained from the Department of Informatics of Brazilian Public Health System (DATASUS) through the Health Information section (http://www2.datasus.gov.br/DATASUS/index.php?area = 0203, last accessed in September, 10th, 2017). The DATASUS database provides a universal coverage of Brazilian population. Further information about DATASUS is described elsewhere [15].

Results

From 2003 to 2016, a total of 69,791 admissions due to VZV were identified in patients aged less than 20 years. Comparing pre and post-vaccination periods, the incidence of hospitalizations in the vaccinated group (1–4 years) significantly decreased from 27.33 to 14.33 per 100000 per year, a reduction of 47.60% (95% confidence interval (CI) 18.19–77.04%, p < 0.001), as shown in Fig. 1. The changes were not significant in other age groups. The percentage change in admissions was (mean and CI95%)

Discussion

This is the first study showing an early nationwide impact of a universal single dose of varicella vaccine on VZV-related hospitalizations in a large, middle-income country as Brazil. Although previous evidences about VZV vaccination effectiveness are available, the nationwide data on the impact of universal VZV immunizations on hospitalizations are derived mostly from high-income countries such as USA, Germany, Canada and Australia, with few data from Latin America [7], [9], [10], [12], [18],

Conflict of interests

The authors declare no conflict of interests.

Acknowledgements

The authors acknowledge the Brazilian Health Institutions that have developed DATASUS database and make it available for universities and researchers: Department of Informatics of SUS and Brazilian Ministry of Health.

Funding

The authors declare that our study had no funding.

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    Contributions of each author: All authors have approved the final version of our manuscript. The following authors: Marcelo C. Scotta, Rolando Paternina-de la Ossa Marcus H Jones, Rita Mattiello and Leonardo A. Pinto had active role in conception and design of our study. Rolando Paternina-de la Ossa and Magali S. Lumertz collected data, Marcelo C. Scotta checked data quality and Rita Mattiello analyzed them. Marcelo C. Scotta, Magali S. Lumertz, Marcus H. Jones and Leonardo A. Pinto had more active role in drafting the article and all other authors critically reviewed the article and contributed to the final content.

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