The effectiveness of maternal pertussis vaccination in protecting newborn infants in Brazil: A case-control study

doi:10.1016/j.vaccine.2019.03.049

Vaccine

Volume 37, Issue 36, 23 August 2019, Pages 5481-5484

https://doi.org/10.1016/j.vaccine.2019.03.049 Get rights and content

Abstract

Introduction

In 2014, the Brazilian Ministry of Health (MoH) recommended Tdap to pregnant women in response to a significant increase in the incidence of pertussis among infants. The present study assessed the effectiveness of maternal immunization in preventing pertussis in infants.

Methods

An unmatched case-control study was undertaken in São Paulo State, Brazil from February 2015 to July 2016. Cases were infants aged <8 weeks at onset of pertussis reported to the Surveillance System and confirmed by real-time polymerase chain reaction or culture. Four to six healthy infants were selected as controls per case from birth certificates in the Information System on Live Births database. General characteristics and mother’s vaccination status were compared between cases and controls. The vaccine effectiveness (VE) was calculated as 1 – odds ratio (OR). For the adjusted VE, the OR was calculated using logistic regression analysis.

Results

Forty-two cases and 248 controls were enrolled in the study. Mothers of 8 cases (19.1%) and 143 controls (57.4%) were vaccinated during pregnancy, resulting in an unadjusted VE of 82.6% (95% confidence interval [CI], 60.8–92.3%). The VE was unchanged after adjusting for maternal age and monthly household income.

Conclusion

Maternal pertussis vaccination during pregnancy was effective in protecting infants aged <8 weeks from pertussis.

Introduction

Pertussis is a highly contagious respiratory disease caused by Bordetella pertussis (1, 2). The disease most commonly affects infants and young children and can induce uncontrollable violent coughing for long periods [1], [2]. Globally, the childhood vaccination with pertussis-containing vaccines has reduced the incidence of the disease [2], [3].

In Brazil, the current routine childhood vaccination schedule includes three doses of the diphtheria-tetanus-whole-cell pertussis + Haemophilus influenzae b + hepatitis B (DTwP-Hib-HBV) pentavalent vaccine, given at 2, 4 and 6 months of age, followed by two boosters doses of DTwP at 15 months and 4 years of age [4], [5]. DTwP vaccine coverage reached the national goal of 95% during the 1990s, resulting in a great decrease of the number of pertussis cases. However, a significant increase in pertussis incidence rates was observed in this country from 2011 to 2014 [4], [5]. As a result, the Brazilian Ministry of Health (MoH) recommended Tdap be given to women between the 27th and 36th week of pregnancy, in 2014 [4], [5]. In 2017, the MoH extended the recommendation to the 20th week of pregnancy [4].

Considering the limited data available concerning effectiveness of maternal pertussis vaccination when vaccination during pregnancy was introduced into the national vaccination schedule, the Immunization Program of São Paulo State, Brazil, developed studies of the effectiveness and immunogenicity of Tdap in pregnant women for post implementation evaluation.

The present study is an unmatched case-control evaluation aimed to assess the effectiveness of maternal Tdap vaccination during pregnancy in preventing pertussis in infants younger than 2 months of age in São Paulo State, Brazil.

Section snippets

Settings and study population

São Paulo State has a population of 45.5 million accounting one-fifth of Brazilian population. This is the wealthiest state of Brazil and responsible for one-third of nationaĺs gross domestic product. The study included under-2-months of age cases and controls from the metropolitan areas of São Paulo, Sorocaba and Campinas. These metropolitan regions together have a population of 33.4 million inhabitants (74.2% of the State population) [6].

Case and control definitions

A case of pertussis was defined as clinically

Results

During the study period of February 1st 2015 to July 31th 2016, 53 (54.6%) of 97 pertussis cases aged <2 months in São Paulo State were from the metropolitan areas of São Paulo, Sorocaba and Campinas. A total of 42 incident, laboratory-confirmed cases of pertussis was enrolled in the study. Among the 11 excluded cases, 9 were not found at the addresses registered in SINASC, 2 were <37 weeks’ gestational age or weight <2500 g at birth, and one mother refused to participate in the study. As

Discussion

We found a high level of effectiveness (83%) for maternal Tdap vaccination during pregnancy in preventing pertussis in infants before their first dose of DTwP, a result consistent with those of earlier studies. An assessment of the maternal vaccination program in England showed a vaccine effectiveness of 91% (95% CI, 84 to 95%) among infants <3 months of age [7], while another case-control in England estimated that maternal vaccination with Tdap had an effectiveness of 93% in protecting infants

Funding source

This work was supported by the Fundo Especial de Saúde para Imunização em Massa e Controle de Doenças (FESIMA), Instituto Adolfo Lutz, Coordenadoria de Controle de Doenças, Secretaria de Estado da Saúde de São Paulo – SP, and the São Paulo Research Foundation, FAPESP [2015/16157-1].

Contributors' statement

Drs Fernandes, Sato, Vaz-de-Lima, de Brito, Luna, Sato, and Dr de Castilho conceptualized and designed the study, drafted the initial manuscript, and reviewed and revised the manuscript.
Dr Sato, Rodrigues, Dr Carvalhanas, Ramos, and Leite selected possible cases and controls in the databases.
Dr Fernandes, Dr Sato, Dr Vaz-de-Lima, Rodrigues, Dr Carvalhanas, Dr Sato and Ramos designed the data collection instruments.
Dr Fernandes, Ramos, Leite, Dr Carvalhanas, and Dr Sato coordinated the fieldwork.

Acknowledgments

We would like to thank the Fundo Especial de Saúde para Imunização em Massa e Controle de Doenças (FESIMA), Instituto Adolfo Lutz, Coordenadoria de Controle de Doenças, and the São Paulo Research Foundation, FAPESP [2015/16157-1] for supporting this study. The Maternal Pertussis Vaccine Working Group also consists of: Edna M. de Souza, Jane H. Atobe, Carmem A F Oliveira (Centro de Imunologia, Instituto Adolfo Lutz), José Cassio de Moraes (Faculdade de Ciências Médicas da Santa Casa de São

Conflicts of interest

The authors have no conflicts of interest relevant to this article to disclose.

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The objective of the article is to describe the main results of pertussis surveillance in Catalonia and to evaluate its evolution in recent years.
According to the case definition in Catalonia, suspicious and confirmed cases notified to the Obligatory Disease Declaration System (MDO) for the period 2011-2018 have been included, after the validation of the notification made by health professionals to this system has been completed.
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Effectiveness of maternal immunisation with a three-component acellular pertussis vaccine at preventing pertussis in infants in the United States: Post-hoc analysis of a case-control study using Bayesian dynamic borrowing
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Effectiveness of third-trimester pregnancy immunisation with Td3ap at preventing infant pertussis in the US is very likely to be ≥ 50% and is most likely ∼ 80%. Bayesian dynamic borrowing of non-US VE data allowed overcoming the limited power (due to small sample size) of a brand-specific sub-analysis by considering additional evidence.
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The effectiveness of maternal pertussis vaccination in protecting newborn infants in Brazil: A case-control study

Abstract

Introduction

Methods

Results

Conclusion

Introduction

Section snippets

Settings and study population

Case and control definitions

Results

Discussion

Funding source

Contributors' statement

Acknowledgments

Conflicts of interest

Lancet

Molecular pathogenesis, epidemiology, and clinical manifestations of respiratory infections due to Bordetella pertussis and other Bordetella subspecies

Clin Microbiol Rev

Pertussis in Latin America: epidemiology and control strategies

Expert Rev Anti-Infective Ther

Challenges of interpreting epidemiologic surveillance pertussis data with changing diagnostic and immunization practices: the case of the state of Sao Paulo, Brazil

BMC Infect Dis

Increasing incidence of pertussis in Brazil: a retrospective study using surveillance data

BMC Infect Dis