Rubella control in Papua New Guinea: Age-specific immunity informs strategies for introduction of rubella vaccine

Aim

To determine the age specific immunity profile for rubella from three discrete study populations in Papua New Guinea, and to inform policy regarding the possible introduction of rubella vaccine.

Background

In 2005, the Western Pacific Region (WPR), of which Papua New Guinea (PNG) is a member state, declared the goal of regional measles elimination by 2012. Recently, WPR has incorporated an accelerated control goal for rubella and congenital rubella syndrome (CRS). PNG currently recommends two doses of measles vaccination at 6 and 9 months of age with a monovalent measles vaccine, which does not include rubella vaccine.

Methods

Convenience samples were collected from 1326 eligible participants in PNG and assessed for rubella immunity using the Dade Behring Enzygnost™ Anti-Rubella-Virus enzyme immunoassay. Nearly 34% were collected during an age stratified prospective survey of febrile patients in Madang Province; approximately 49% were collected from women of childbearing age in East Sepik and Milne Bay Provinces. Remaining specimens were collected from 6 to 7-month-old infants in Port Moresby prior to receiving the first dose of measles vaccine.

Findings

Of all samples tested, 65.2% (95% confidence interval (CI): 62.6–67.8) had evidence of immunity to rubella infection. Of women more than 15 years of age, 91.6% (95% CI: 89.4–93.5) were immune. The force of infection was highest between 5 and 19 years of age.

Conclusions

Although a population-based sample was not used, our multi-centre study of the population immunity profile suggests that immunity against rubella is extremely high in most women of childbearing age, but women who become pregnant at an early age may be at high risk of rubella infection during pregnancy and potential delivery of an infant with CRS. Routine measles vaccine coverage, a proxy for measles-rubella vaccine coverage, as measured in recently published studies, is well below the WHO target of 80% coverage. Introduction of a child or infant dose of rubella vaccine requires caution and further study.     

A systematic review of rubella vaccination strategies implemented in the Americas: impact on the incidence and seroprevalence rates of rubella and congenital rubella syndrome

Objective

To evaluate the impact of rubella vaccination strategies on the rates of acquired rubella and congenital rubella syndrome in the Americas.

Methods

We conducted a systematic review of the literature (MEDLINE, PubMed, EMBASE, Cochrane Library, Artemisa Database, LILACS Database, Evidence Portal, VHL-PAHO Portal, Scielo, and Grey-Literature sources) that was published from 1969–2010. We included studies on rubella incidence and seroprevalence rates that were associated with rubella vaccination. The quality of the studies was evaluated according to international guidelines.

Results

A total of 14 studies were identified: 2 clinical trials, 2 cohort studies, 3 transversal studies, 5 ecological studies, and 2 mathematical models. Childhood vaccination reduced the incidence of rubella by 23.6% to 99.6%, increased the occurrence of epidemic cycles in Argentina and in the United States, and shifted the illness to susceptible adults. Vaccination strategies that focused on women and children in Brazil were associated with a 5.5-fold greater incidence of rubella in men leading to new outbreaks and CRS. A combined vaccination strategy with a universal approach that included routine vaccination for boys, girls, women, and men in Mexico and in Costa Rica reduced the incidence of rubella by more than 98% and led to absence of CRS since 2008. A medium and a low risk of bias were found in 3 and 4 articles, respectively.

Conclusion

The results of this review demonstrate that the combined vaccination strategy with a universal approach was the most effective strategy as evidenced by a drastic reduction in the number of cases and the interruption of endemic transmission of rubella in the Americas.     

Prevention of perinatal hepatitis B virus transmission in the Netherlands, 2003-2007: children of Chinese mothers are at increased risk of breakthrough infection

Background

In the Netherlands, different hepatitis B vaccination schedules have been used for children born to HBV-infected mothers. All schedules included a birth dose of hepatitis B immunoglobuline (HBIg). We assessed determinants of perinatal HBV transmission and determinants of anti-HBs titers in infants born to HBsAg positive mothers.

Methods

We included infants born to HBV infected mothers between 1.1.2003 and 30.6.2007, using national databases and a separate database for Amsterdam. Risk factors for perinatal transmission and determinants of the anti-HBs titer were studied using logistic and linear regression, respectively.

Results

Of 2657 infants registered in the national database, 91% were registered to have received HBIg and at least three hepatitis B vaccinations. In Amsterdam, this coverage among 413 children at risk was higher (96%, p < 0.01). Serological test results for 2121 infants (80%) indicated that 13 (0.6%) were HBsAg positive. A mother of Chinese descent was the only risk factor for perinatal HBV infection identified (RR 9.1, 95% CI 3.1–26.8). Receiving a birth dose of hepatitis B vaccine later than in the first week of life was not associated with an increased risk of perinatal HBV infection. A shorter period between last vaccination and testing, and having received more doses of hepatitis B vaccine were independently associated with a higher anti-HBs titer.

Conclusions

Infants born to Chinese mothers were at increased risk of perinatal HBV infection. All HBsAg positive pregnant women of Chinese origin should be assessed to determine whether there is an indication for anti-viral treatment during pregnancy. Among infants who received HBIg at birth, we did not detect an increased risk of perinatal HBV infection when the first dose of hepatitis B vaccine was administered after the first week of life.     

Rubella seroprevalence in the first birth cohort reaching fertility age after 20 years of two dose universal vaccination policy in Israel

Background

A national program of a 2-dose universal childhood MMR vaccination policy has been in effect in Israel since 1988. As the 1988 birth cohort reached fertility age, questions regarding immunity against rubella were raised.

Objective

To assess the seroprevalence of rubella IgG antibodies among young Israeli adults born after 1987 in comparison to previous birth cohorts, in order to determine evidence based policy for prevention of rubella and congenital rubella syndrome.

Methods

We conducted a seroprevalence study of rubella IgG antibodies among 416 Israeli adults (42.5% females) born in 1988–1989, based on a representative sample of sera collected at age 18–19 upon recruitment to mandatory military service in 2007.

Results

In total, 87.7% were seropositive (>15 IU/ml) as compared with 84.8% in the 1999 recruitment (P = 0.26) and 93.4% in 1987 (P = 0.004). Yet there was a difference by gender. The proportion of seropositives among female young adults (92.7%) was significantly lower as compared to those measured in the 1999 (99.2%, P = 0.001) and 1987 (99.0%, P = 0.006) recruitments. The proportion of seropositives among males (84.1%) was significantly higher as compared to those measured in 1999 (73.0%, P < 0.001) but similar to those of 1987 (88.8%, P = 0.13). Females born in the FSU were found to be high risk groups as 11.5% were seronegative.

Conclusions

Our findings indicate that despite a successful program of congenital rubella syndrome prevention in Israel, there is a decline in seroprevalence among female young adults, especially immigrants from the FSU. A proactive catch-up program for females, especially for those of higher risk for susceptibility should be considered in Israel and in other countries.     

Seroprevalence of rubella in female migrant factory workers in Shenzhen, China

Background

Rubella remains a common disease in Mainland China and is a major cause of severe birth defects from Congenital Rubella Syndrome (CRS). Rubella-containing vaccines were not included in China's National Expanded Program of Immunization (NEPI) until December 2007. In Shenzhen, women of childbearing age make up a large percentage of its migrant factory worker population. Understanding their immunity to rubella is critical in furthering efforts towards rubella vaccination programs.

Objectives

To investigate the seronegativity of rubella antibodies and evaluate potential associates of rubella immunity among female migrant factory workers in Shenzhen, China.

Subjects and Methods

: Serum samples were collected from 518 female migrant workers, aged 18–55, working in 44 randomly selected factories in Shenzhen, China during May through June of 2009. Samples were tested for Rubella Immunoglobulin G (IgG) using a commercial Enzyme-linked immunosorbant assay kit. Self-reported vaccination histories and socio-demographic information were also collected.

Results

Of 518 female workers, 402 (77.6%) were immune to rubella. Significant differences in seronegativity were dependent on region of origin, being without a job contract, age group, marital status and seronegativity of measles.

Conclusions

Seroprevalence of antibodies to rubella in Shenzhen, China amongst female migrant workers is too low to provide immunity in the population. Given the high numbers of women of childbearing age amongst Shenzhen migrant factory workers coming from many provinces across China, local health authorities in Shenzhen should consider combining new rubella immunization programs with existing measles immunization efforts in this population.     

Brief report: Imported case of congenital rubella syndrome--New Hampshire, 2005

In 2004, an independent panel convened by CDC declared rubella no longer endemic in the United States. Nine cases of rubella were reported in 2004, and four cases of congenital rubella syndrome (CRS) were reported during 2001-2004. However, worldwide, an estimated 100,000 infants are born with CRS annually. This report describes a case of imported CRS diagnosed in an infant girl aged 10 weeks born in New Hampshire to Liberian refugee parents. To prevent transmission of rubella, clinicians should consider a diagnosis of CRS in infants with compatible clinical signs, particularly those born to mothers who recently immigrated from countries without rubella control programs, and rubella vaccine should be administered to susceptible persons.     

Using data to guide policy: Next steps for preventing perinatal hepatitis B virus transmission in Cambodia

Background

Cambodia is highly endemic for hepatitis B virus (HBV) infection. Preventing perinatal HBV transmission should be prioritized in health facilities by providing hepatitis B vaccination to all infants within 24 h of birth (timely birth dose coverage).

Methods

Teams assessed birth dose policy, practices and coverage in hospitals and health facilities in 10 provinces in Cambodia.

Results

Fifty-one sites were assessed. Median (interquartile range) timely birth dose coverage was 66% (48–92%); coverage was 88% (range = 60–96%) in facilities vaccinating on-site and 48% (range = 20–52%) in those referring off-site (p < 0.0001). Overall, 5 (29%) of 16 hospitals that referred vaccination off-site did not tell mothers vaccination should take place within 24 h of birth, and 6 (35%) discharged mothers when no vaccination services were available for infants to receive the birth dose.

Conclusions

Newborns can miss a time-sensitive opportunity to be protected against perinatal HBV infection when they are referred for vaccination off-site rather than being vaccinated in the delivery facility. These data support the case to strengthen policies and practices to provide hepatitis B birth dose vaccination in the delivery facility.     

Seroprevalence of measles and rubella antibodies in pregnant women Haiti, 2012

Background

Haiti had set a national goal to eliminate measles and rubella, as well as congenital rubella syndrome (CRS) by 2010. A 2007–2008 nationwide measles and rubella vaccination campaign targeting 1–19 years, however, reached only 79% of the target population. To assess whether population immunity was adequate to support elimination, we conducted a national serosurvey.

Methods

We systematically selected 740 serum specimens collected from pregnant women in a 2012 national antenatal HIV sentinel serosurvey across four age strata: 15–19, 20–24, 25–29 and 30–39 years. Sera were tested for measles and rubella specific immunoglobulin G antibodies (IgG) using commercial immunoassays. We classified sera as seropositive, seronegative or indeterminate per manufacturer's instructions, and analyzed seroprevalence according to age strata, and rural or urban residence. We assessed immunity by estimating antibody concentrations in international units per milliliter (IU/mL) for seropositive and indeterminate sera. Measles IgG concentrations >0.12 IU/mL and rubella IgG concentrations >10 IU/mL were considered clinically protective.

Results

Of 740 sera, 696 (94.1%) were seropositive and 20 (2.7%) were indeterminate for measles IgG; overall 716 (96.8%) sera had IgG concentrations >0.12 IU/mL. For rubella IgG, 691 (93.4%) sera were seropositive and 1 (0.1%) was indeterminate; a total of 687 (92.8%) had IgG concentrations >10 IU/mL. Measles seropositivity varied across age strata (p = 0.003); seropositivity increased from 88.6% among 15–19 year olds to 98.4% among 30–39 year olds (Cochran–Armitage trend test ≤ 0.0001). Rubella seropositivity did not differ across age strata. There were no statistically significant differences in measles or rubella seropositivity by urban versus rural residence.

Conclusion

Despite previous low vaccination coverage for measles, results from this serosurvey indicate high levels of measles and rubella seropositivity in pregnant women, and contribute to the evidence for measles, rubella and CRS elimination from Haiti by the target date.     

Economic evaluation of universal newborn hepatitis B vaccination in China

Objective

To estimate the long-term cost-effectiveness of universal newborn hepatitis B vaccination in China, an area of high endemicity.

Method

A decision tree was used to describe perinatal hepatitis B virus (HBV) transmission, early infection and impact of vaccination. A Markov model based on 1-year cycles was used to simulate these impacts for the lifetime of a cohort of 10,000,000 infants born in 2002 in China. We compared both cost and health outcomes for two strategies: universal newborn vaccination comprising a timely birth dose (HepB1) with a three-dose vaccination (HepB3) compared with no vaccination. Univariate and probabilistic sensitivity analyses using Monte Carlo simulations were performed to test parameter uncertainty.

Results

Over the cohort's lifetime, 79,966 chronic infections, 37,553 cases of hepatocellular carcinoma (HCC) and 130,796 HBV related deaths would be prevented by universal infant vaccination. The prevalence of HBV infection is reduced by 76%. Over 743,000 life-years and 620,000 quality adjusted life years (QALYs) would be gained and there would be monetary benefits of more than 1 billion US dollars in medical care costs and lost productivity avoided.

Conclusion

The newborn vaccination programme for Hepatitis B in China both gains QALYs and saves medical care costs. It is important to ensure that timely and comprehensive vaccination programmes continue.     

Modeling the potential impact of vaccination on the epidemiology of congenital cytomegalovirus infection

Background

Understanding the potential for vaccination to change cytomegalovirus (CMV) epidemiology is important for developing CMV vaccines and designing clinical trials.

Methods

We constructed a deterministic, age-specific and time-dependent mathematical model of pathogen transmission, parameterized using CMV seroprevalence from the United States and Brazil, to predict the impact of vaccination on congenital CMV infection.

Findings

Concurrent vaccination of young children and adolescents would result in the greatest reductions in congenital CMV infections in populations with moderate and high baseline maternal seroprevalence. Such a vaccination strategy, assuming 70% vaccine efficacy, 90% coverage and 5-year duration of protection, could ultimately prevent 30–50% of congenital CMV infections. At equilibrium, this strategy could result in a 30% reduction in congenital CMV infections due to primary maternal infection in the United States but a 3% increase in Brazil. The potential for an increase in congenital CMV infections due to primary maternal infections in Brazil was not predicted with use of a vaccine that confers protection for greater than 5 years.

Interpretation

Modeling suggests that vaccination strategies that include young children will result in greater declines in congenital CMV infection than those restricted to adolescents or women of reproductive age. Our study highlights the critical need for better understanding of the relative contribution of type of maternal infection to congenital CMV infection and disease, the main focus of vaccine prevention.     

Prevalence of chronic hepatitis B virus infection before and after implementation of a hepatitis B vaccination program among children in Nepal

Background

In Nepal, an estimated 2–4% of the population has chronic hepatitis B virus (HBV) infection. To combat this problem, from 2002 to 2004, a national three dose hepatitis B vaccination program was implemented to decrease infection rates among children. The program does not currently include a birth dose to prevent perinatal HBV transmission. In 2012, to assess the impact of the program, we conducted a serosurvey among children born before and after vaccine introduction.

Methods

In 2012, a cross-sectional nationally representative stratified cluster survey was conducted to estimate hepatitis B surface antigen (HBsAg) prevalence among children born from 2006 to 2007 (post-vaccine cohort) and among children born from 2000 to 2002 (pre-vaccine cohort). Demographic data, as well as written and oral vaccination history were collected. All children were tested for HBsAg; mothers of HBsAg positive children were also tested. Furthermore, we evaluated the field sensitivity and specificity of the SD Bioline HBsAg rapid diagnostic test by comparing results with an enzyme immunoassay.

Results

Among 2181 post-vaccination cohort children with vaccination data by either card or recall, 86% (95% confidence interval [CI] 77–95%) received ≥3 hepatitis B vaccine doses. Of 1200 children born in the pre-vaccination cohort, 0.28% (95% CI 0.09–0.85%) were positive for HBsAg; of 2187 children born in the post-vaccination cohort, 0.13% (95% CI 0.04–0.39%) were positive for HBsAg (p = 0.39). Of the six children who tested positive for HBsAg, two had mothers who were positive for HBsAg. Finally, we found the SD Bioline HBsAg rapid diagnostic test to have a sensitivity of 100% and a specificity of 100%.

Conclusions

This is the first nationally representative hepatitis B serosurvey conducted in Nepal. Overall, a low burden of chronic HBV infection was found in children born in both the pre and post-vaccination cohorts. Current vaccination strategies should be continued.     

Cost-effectiveness of routine vaccination of adolescent females against cytomegalovirus

Background

Congenital cytomegalovirus (CMV) infection is associated with significant infant morbidity and mortality. A prophylactic vaccine to prevent congenital CMV infection is expected to be available in the near future, and will likely be targeted to adolescent females.

Methods

Using a decision tree, we compared the costs, potential clinical impacts, and cost-effectiveness of the current strategy of no CMV vaccination versus a strategy where all adolescent females are vaccinated against CMV prior to their first pregnancy. Both maternal outcomes related to vaccination, and infant outcomes related to congenital CMV infection, were considered in the model.

Results

Under base-case conditions, our analysis suggested that vaccinating all adolescent females against cytomegalovirus would be both less costly and with greater clinical benefits than not vaccinating. Among a population of 100,000 adolescent females, the vaccination strategy cost $32.3 million dollars less than not vaccinating, and avoided substantial numbers of infants affected with hearing loss, vision loss, and mental retardation, and 8 infant deaths. Our model was most sensitive to variations in vaccine efficacy. When vaccine efficacy against disease was less than 61%, not vaccinating became the preferred strategy because it was less expensive than vaccinating, without substantial changes in clinical benefits to the population.

Conclusions

Under a wide variety of conditions, universal vaccination of adolescent females to protect their future children against congenital CMV infection was cost effective. However, for this to be preferred over not vaccinating, our results suggest that vaccine efficacy against disease would need to be at least 61%.     

The end of the Australia antigen? An ecological study of the impact of universal newborn hepatitis B vaccination two decades on

Background

A universal newborn hepatitis B (HBV) vaccination program was introduced in the Northern Territory of Australia in 1990, followed by a school-based catch-up program. We evaluated the prevalence of hepatitis B infection in birthing women up to 20 years after vaccination and compared this to women born before the programs commenced.

Methods

A cohort of birthing mothers was defined from Northern Territory public hospital birth records between 2005 and 2010 and linked to laboratory confirmed notifications of chronic HBV, based principally on a record of hepatitis B surface antigen detection. Prevalence of HBV was compared between women born before or after implementation of the newborn and catch-up vaccination programs.

Findings

Among 10797 birthing mothers, 138 (1.3%) linked to a chronic HBV record. HBV prevalence was substantially higher in Aboriginal women compared to non-Indigenous women (2.4% versus 0.04%; p < 0.001). Among 5678 Aboriginal women, those eligible for catch-up and newborn HBV vaccination programs had a significantly lower HBV prevalence than older women born prior to the programs: HBV prevalence respectively 2.2% versus 3.5%, (OR 0.61, 95%CI 0.43–0.88) and 0.8% versus 3.5% (OR 0.21, 95%CI 0.11–0.43). This represents a risk reduction of respectively 40% and 80% compared to unvaccinated women.

Interpretation

The progressively greater reduction in the prevalence of chronic HBV in adult Aboriginal women co-inciding with eligibility for catch-up and newborn vaccination programs is consistent with a significant impact from both programs. The use of data derived from antenatal screening to track ongoing vaccine impact is applicable to a range of settings globally.     

Mass Measles Rubella Immunization Campaign: Bhutan Experience

Background:

Bhutan has attained universal child immunization since 1991. Since then, immunization coverage is maintained at high level through routine immunization, periodic National Immunization Days, and mop up campaigns. Despite high immunization coverage, every year, significant numbers of clinically suspected measles cases were reported.

Objective:

To assess the cause of continuing high “suspected measles cases” and take appropriate public health measures.

Materials and Methods:

Febrile rash outbreaks occurred in several districts in 2003. These episodes were investigated. Simultaneously, a retrospective data search revealed evidence of congenital rubella syndrome (CRS) in the country.

Results:

Thirty five percent of the tested samples were positive for rubella but none for measles. There were evidences of the presence of CRS. This was discussed in the annual health conference 2004, amongst health policy makers and district heads who recommended that a possibility of inclusion of rubella as an antigen be looked into. A nationwide measles and rubella immunization campaign was conducted in 2006 followed by introduction of rubella vaccine in the immunization schedule.

Conclusion:

Febrile rash can be caused by a host of viral infections. Following universal measles immunization, it is pertinent that febrile rash be looked in the light of rubella infections. Following the introduction of rubella vaccination in the national immunization schedule, there has been significant reduction of febrile rash episodes, cases of rubella, and congenital rubella syndrome.     

A rubella outbreak investigation and BRD-II strain rubella vaccine effectiveness study,Harbin city,Heilongjiang province,China, 2010–2011

Background

In the 1990s, China introduced rubella vaccine into the private market using BRD-II virus strain, which is different than the globally used RA27/3 strain. In 2007, BRD-II rubella containing vaccine was introduced into the national immunization program and recommended for routine use. However, to our knowledge, there are no field vaccine effectiveness (VE) studies of BRD-II rubella vaccine. In April 2011, a rubella outbreak was detected in two daycare centers in Harbin city, China. We conducted an investigation to determine VE of BRD-II rubella vaccine.

Methods

Rubella cases were either laboratory-confirmed or epidemiologically linked to laboratory-confirmed cases. We collected demographic characteristics, migrant status, and history of rubella and measles vaccination from all children in the two daycare centers.

Results

The first case of rubella was on 22 November, 2010. Among the 143 children in the two daycare centers, 22 acquired rubella, for an overall attack rate (AR) of 15.4% (22/143). The AR in higher-grade classes (21.7%) was higher than in lower grade classes (3.9%). The AR among migrant children (47.8%) was higher than among local children (9.2%). Rubella vaccine coverage was 17% (24/143), while measles vaccine coverage was 100%. The AR among rubella-vaccinated children was 0% (0/24), and the AR among rubella-unvaccinated children was 18.5% (22/119), for a VE of 100% (P value = 0.025, 95% CI: 35–100%). Rubella vaccine coverage among children born before 2007 was 10.2% (10/98), and was lower than that for children born in 2007 or after (31.1% (14/45), RR = 0.33, 95%CI: 0.16–0.68). Emergency vaccination was conducted on 11 and 12 April 2011, and the outbreak stopped in one week later.

Conclusions

Domestic BRD-II strain rubella vaccine showed high vaccine effectiveness against rubella. Rubella vaccine coverage through routine immunization was insufficient. Consideration should be given for measuring rubella vaccine coverage to determine the need for catch-up vaccination in China.     

Surveillance and Control of Rubella in the Republic of Korea From 2001 to 2009: The Necessity for Enhanced Surveillance to Monitor Congenital Rubella Syndrome

Objectives

The aim of this study was to review the epidemiologic data of rubella and congenital rubella syndrome (CRS) supplied by surveillance systems from 2001 to 2009 and to propose measures to improve the quality of the surveillance system in the Republic of Korea.

Methods

The epidemiological data for rubella and CRS cases reported to the Korea Centers for Disease Control and Prevention from 2001 to 2009 were retrospectively reviewed, and insurance reimbursement data from the Korea National Health Insurance Review Agency were collected for comparison.

Results

The number of yearly reported rubella cases to the Korea Centers for Disease Control and Prevention from 2001 to 2009 was 128, 24, 8, 24, 15, 12, 35, 30, and 36, respectively. The occurrence of rubella shifted to a slightly higher age group during the 9-year period, i.e. from 0–9 years to 10–19 years. Among the 309 reported rubella cases, three were confirmed cases of CRS. In addition, according to data sourced from Health Insurance Review Agency, 24, 19, 19, 9, and 5 CRS cases were reported for medical insurance reimbursement from 2005 to 2009, respectively.

Conclusion

According to available surveillance data, the reported cases of rubella and CRS were not high, but a more detailed surveillance with emphasis on susceptible women of childbearing age is necessary for better monitoring and control of rubella and CRS in the Republic of Korea.Key words: congenital rubella syndrome, monitor, rubella, surveillance     

Pregnant women's intention to take up a post-partum pertussis vaccine,and their willingness to take up the vaccine while pregnant: A cross sectional survey

Introduction

Post-partum vaccination of new mothers is currently recommended in Australia to reduce pertussis infection in infants. Internationally, vaccination recommendations now include pregnant women in some countries. Understanding the awareness of pertussis vaccination recommendations among pregnant women, and their willingness to have the vaccine while pregnant is important for informing vaccine program implementation.

Objective

To determine awareness and intentions toward current recommendations for post-partum pertussis vaccination among Australian pregnant women, and their willingness to accept pertussis vaccine during pregnancy, should it be recommended in Australia in the future.

Design

Quantitative self-administered survey, using a non-random stratified sampling plan based on representative proportions by age, parity and region of residence.

Participants and setting

Pregnant women receiving antenatal care through three large, demographically diverse referral hospitals in metropolitan, urban and rural New South Wales, Australia.

Results

The response rate was 815/939 (87%). Most women (80%) reported willingness to have the pertussis vaccine during pregnancy, should it be recommended. Thirty four per cent of women intended to receive a pertussis vaccine post-partum, 17% had received it previously, while 45% had never heard of pertussis vaccine, had not thought about it, or were undecided about having it. Compared with those who had not received a recommendation to have the vaccine post-partum, women who had received a recommendation were 7 times more likely (95% CI 4–14) to report intention to have the vaccine.

Conclusions

Health care provider recommendation is paramount to raising awareness of pertussis vaccination recommendations among pregnant women. Women's willingness to have the vaccine while pregnant is encouraging, and indicates the potential for high pertussis vaccine coverage among pregnant women, should it be recommended in Australia.     

The epidemiology of rubella and congenital rubella in Australia, 1992 to 1997.

Selective rubella vaccination of schoolgirls commenced in 1971 and was followed by a significant reduction in congenital rubella. Infant vaccination with MMR was introduced in 1989 to interrupt circulation of the virus in young children, and in 1994/95 the adolescent school based rubella vaccination program was changed to MMR for both boys and girls. This report reviews the epidemiology of rubella and congenital rubella between 1992 and 1997 using reports to the National Notifiable Diseases Surveillance System (NNDSS) and the Australian Paediatric Surveillance Unit (APSU). Notification rates for rubella exceeded 20 per 100,000 in 1992, 1993 and 1995 and declined to 7.2 per 100,000 in 1997. Sixty-one per cent of notifications occurred between September and December and 68% occurred in males. The incidence rate in males aged 15-22 years peaked at 152.6 per 100,000 in 1995 reflecting the lack of immunisation in this cohort. From 1993 to 1997, 19 children were reported with congenital rubella syndrome, representing 1 in 67,000 live births. Of these, 17 had multiple defects (4 died) and 2 had deafness only. There were also 5 infants with congenital rubella infection but no defects. Australia's rate of congenital rubella syndrome exceeded that of the United Kingdom and the United States of America but this may be partly attributable to differences in reporting practices. The impact of changing the second dose of MMR vaccine to 4 years of age in 1998 will require careful monitoring.     

Sources of pertussis infection in young infants: A review of key evidence informing targeting of the cocoon strategy

Background

The relative contribution of different categories of contact in transmitting pertussis to very young infants, who experience the most severe morbidity, is the most important single factor determining the likely benefit of pertussis vaccination of their close contacts (the “cocooning” strategy).

Objective

To identify, evaluate the quality of and summarise existing data on potential sources of infant pertussis infection in high income countries, focussing on infants under 6 months old.Data sources: Online databases MEDLINE and EMBASE. Additional studies were identified from the reference lists of relevant articles.Study selection and analysis: Study quality was evaluated by standardised criteria, based on the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Pooled estimates of the proportion of pertussis cases attributable to various contact sources were calculated using data from the highest quality studies.

Results

Nine studies met the inclusion criteria; seven included data on contacts of hospitalised infants less than 6 months old. Case definitions and methods of contact ascertainment were variable. Most identified sources were from the household, of which 39% (95%CI 33–45%) were mothers, 16% (95%CI 12–21%) fathers, and 5% (95%CI 2–10%) grandparents. Estimates for siblings (16–43%) and non-household contacts (4–22%) were more heterogeneous. For 32–52% of infant cases, no source was identified. Asymptomatic pertussis infection was found in 8–13% of contacts evaluated.

Conclusions

These data suggest that the greatest potential impact of pertussis vaccination of adults to prevent severe disease in young infants comes from vaccinating mothers, followed by fathers, with grandparents having a minor role. Siblings varied in importance and, given recent data regarding waning immunity in vaccinated children, need further study. Non-household sources are also well documented, highlighting the potential limitations of the cocoon strategy to prevent severe infant disease.     

Long-term efficacy of 10-12 years after being immunized with Chinese hamster ovary cell derived hepatitis B vaccine in Chinese Rural Communities

Objective

To evaluate the long-term efficacy of Chinese hamster ovary (CHO) cell derived hepatitis B vaccine in country community in China.

Methods

A cross-sectional investigation was carried out. Children who were born between 1997 and 1999 and vaccinated with the three doses of CHO-derived hepatitis B vaccine were selected as study objects. Their serum samples were taken to test for hepatitis B virus (HBV) markers, and the results were compared to that before vaccination. In addition, for HBsAg positive children, their mothers were visited.

Results

1254 Children were enrolled in the study. The prevalence of HBsAg was 0.24% and the vaccine efficacy was 97.0%, similar to that of yeast derived hepatitis vaccines. Among 3 mothers of HBsAg positive children, 2 were HBsAg positive, indicating maternal HBV transmissions.

Conclusion

The long-term efficacy of the CHO-derived hepatitis B vaccine is good and after vaccination maternal transmission is the most important route of spreading HBV.