Estimating the burden of rubella virus infection and congenital rubella syndrome through a rubella immunity assessment among pregnant women in the Democratic Republic of the Congo: Potential impact on vaccination policy

Tuesday, 20th of December 2016 Print

Vaccine, Volume 34, Issue 51, 12 December 2016, Pages 6502–6511

Estimating the burden of rubella virus infection and congenital rubella syndrome through a rubella immunity assessment among pregnant women in the Democratic Republic of the Congo: Potential impact on vaccination policy

 


Excerpts below; full text is at http://dx.doi.org/10.1016/j.vaccine.2016.10.059

 

Abstract

Background

Rubella-containing vaccines (RCV) are not yet part of the Democratic Republic of the Congo´s (DRC) vaccination program; however RCV introduction is planned before 2020. Because documentation of DRC´s historical burden of rubella virus infection and congenital rubella syndrome (CRS) has been minimal, estimates of the burden of rubella virus infection and of CRS would help inform the country´s strategy for RCV introduction.

Methods

A rubella antibody seroprevalence assessment was conducted using serum collected during 2008–2009 from 1605 pregnant women aged 15–46 years attending 7 antenatal care sites in 3 of DRC´s provinces. Estimates of age- and site-specific rubella antibody seroprevalence, population, and fertility rates were used in catalytic models to estimate the incidence of CRS per 100,000 live births and the number of CRS cases born in 2013 in DRC.

Results

Overall 84% (95% CI 82, 86) of the women tested were estimated to be rubella antibody seropositive. The association between age and estimated antibody seroprevalence, adjusting for study site, was not significant (p = 0.10). Differences in overall estimated seroprevalence by study site were observed indicating variation by geographical area (p ⩽ 0.03 for all). Estimated seroprevalence was similar for women declaring residence in urban (84%) versus rural (83%) settings (p = 0.67). In 2013 for DRC nationally, the estimated incidence of CRS was 69/100,000 live births (95% CI 0, 186), corresponding to 2886 infants (95% CI 342, 6395) born with CRS.

Conclusions

In the 3 provinces, rubella virus transmission is endemic, and most viral exposure and seroconversion occurs before age 15 years. However, approximately 10–20% of the women were susceptible to rubella virus infection and thus at risk for having an infant with CRS. This analysis can guide plans for introduction of RCV in DRC. Per World Health Organization recommendations, introduction of RCV should be accompanied by a campaign targeting all children 9 months to 14 years of age as well as vaccination of women of child bearing age through routine services.


1. Introduction

Rubella is a vaccine-preventable disease with safe and effective vaccines available since 1969. In the absence of vaccination, infection with the rubella virus usually occurs in childhood and causes a mild, self-limited illness characterized by rash and fever. However, if rubella virus infection occurs in a susceptible woman during the first trimester of pregnancy, miscarriage, fetal death, or congenital rubella syndrome (CRS) in the surviving infant often occurs. CRS can result in hearing impairment, blindness, congenital heart disease, mental retardation, and/or other manifestations [1] and [2].

A single dose of the most common rubella vaccine, RA27/3, is highly efficacious in providing lifelong protection against disease. Prevention of congenital rubella virus infection, including CRS, is the primary goal of rubella vaccination. The preferred approach for prevention of rubella and CRS is for countries to introduce a rubella-containing vaccine (RCV) through a wide-age range campaign and then incorporate it into the national childhood vaccination schedule [2].

In recent years, several World Health Organization (WHO) regions have established rubella/CRS elimination or accelerated control goals [2], [3], [4], [5] and [6]. In 2003 the WHO region of the Americas set a rubella/CRS elimination goal, achieved the goal in 2009, and in April 2015, was declared free of endemic rubella and CRS [2], [3], [4], [5] and [7]. The WHO European region set a 2015 rubella elimination goal [3], [4] and [8]. In October 2014, a regional rubella elimination goal for the WHO Western Pacific Region was endorsed by its Regional Committee [6]. The WHO African region has not yet established a rubella elimination goal but recommends that countries document the burden of rubella virus infection/CRS and, when feasible, introduce RCVs [9].

RCVs have not been widely administered in the Democratic Republic of the Congo (DRC) nor introduced into the country´s national vaccination program [10]. However, there are tentative plans for introduction into the childhood vaccination schedule before 2020 [10]. Documentation of DRC´s historical burden of rubella virus infection and CRS has been minimal [1], [11] and [12]. Moreover, DRC has no surveillance system for either disease, but rubella virus transmission within the country has been documented by a rubella antibody seroprevalence assessment conducted in Kinshasa city in 1987–1988 and by measles case-based surveillance since 2005, with serological testing for rubella-specific immunoglobulin type M (IgM) when suspected measles cases are negative for measles IgM [1], [11] and [12]. Considering the interest in rubella control/elimination in the WHO African region, estimates of the burden of rubella virus infection/CRS in DRC are urgently needed [8] and [9]. We describe analyses of sera from 1605 pregnant women aged 15–46 years from 3 provinces in DRC which were available from a human immunodeficiency virus (HIV) sentinel survey among women attending antenatal care (ANC) sites [13], [14] and [15]. Estimates of age- and site-specific rubella antibody seroprevalence, population, and fertility rates were used in catalytic models to estimate the incidence of CRS per 100,000 live births and the number of CRS cases born in 2013 in DRC. These estimates will be valuable to DRC´s Ministry of Public Health (MOPH) in planning for RCV introduction [10].b

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