Impact of rubella vaccination in Australia

Systematic Review of Measles and Rubella Serology Studies

Serological tests provide information about individual immunity from historical infection or immunization. Cross-sectional serological studies provide data about the age- and sex-specific immunity levels for individuals in the studied population, and these data can provide a point of comparison for the results of transmission models. In the context of developing an integrated model for measles and rubella transmission, we reviewed the existing measles and rubella literature to identify the results of national serological studies that provided cross-sectional estimates of population immunity at the time of data collection. We systematically searched PubMed, the Science Citation Index, and references we identified from relevant articles published in English. We extracted serological data for comparison to transmission model outputs. For rubella, serological studies of women of child-bearing age provide information about the potential risks of infants born with congenital rubella syndrome. Serological studies also document the loss of maternal antibodies, which occurs at different rates for the different viruses and according to the nature of the induced immunity (i.e., infection or vaccine). The serological evidence remains limited for some areas, with studies from developed countries representing a disproportionate part of the evidence. The collection and review of serological evidence can help program managers identify immunity gaps in the population, which may help them better understand the characteristics of individuals within their populations who may participate in transmission and manage risks.

Screening, rubella vaccination, and childhood hearing impairment in Taiwan

Childhood hearing impairment (CHI) is a major developmental disability, but data at the national level are limited, especially those on the changes in the prevalence over time. In Taiwan, the government began to certify disabled residents for providing various services in 1980 and maintains a registry of certified cases, which provides a rare opportunity for studying the trends of CHI prevalence. Using the registry data, we estimated the prevalence of CHI by age and severity and explored factors affecting its changes over time. From 2000 to 2011, the registered cases under 17 years old ranged from 3427 to 4075. The overall prevalence increased from 2000 to 2006, but then decreased till 2011. While the prevalence of mild CHI increased over the years, such a pattern was not observed in moderate or severe CHI. In general, the overall prevalence increased over the years in the age groups <3 years, 3-5 years, and 6-11 years (p<0.01), and the largest increase was observed in the age group <3 years, particularly after the promotion of screening by the government in 2003. The decrease after 2006 was mainly attributable to decreases in the age groups 12-14 (with a decreasing trend from 2001, p<0.01) and 15-17 years (with a decreasing trend from 2004, p<0.01). The timing was related to the implementation of a nationwide rubella vaccination program. Similar decreases had been observed in countries with rubella vaccination programs.

The impact of rubella immunisation on the incidence of rubella, congenital rubella syndrome and rubella-related terminations of pregnancy in South Australia

OBJECTIVES

To describe the impact of rubella immunisation on the incidence of rubella, congenital rubella syndrome and rubella-related terminations of pregnancy in South Australia, and to identify factors associated with a re-emerging problem.

DESIGN AND METHODS

A population-based descriptive study using data from South Australian notifications of disease, births and terminations of pregnancy, the rubella immunisation programme, antenatal rubella antibody screening and paediatric hospital case records.

SETTING

South Australia (population 1.48 million people; 20,000 births per year).

MAIN OUTCOME MEASURES

Incidence of rubella (age-sex specific), congenital rubella syndrome and rubella-related terminations of pregnancy; antenatal rubella sero-positive rates; rubella immunisation uptake rates.

RESULTS

Rubella notification rates in 1990-1996 were significantly higher for males than females for ages 15-34 years. There were five cases of congenital rubella syndrome notified in 1980-1996 compared with at least 20 confirmed or compatible cases in 1965-1979. Rubella-related terminations of pregnancy are now rare, with the last termination for maternal rubella being in 1993. The antenatal rubella sero-positive rate in 1995 was 96.7%, but was significantly lower among Asian women born overseas (78.6% among those 30 years or older). Vaccination uptake rates in schoolgirls decreased between 1990 and 1994 (91.2% to 86.9%).

CONCLUSIONS

Since the introduction of rubella immunisation, the incidence of rubella infection among women of reproductive age, and of rubella-related terminations, has fallen. Congenital rubella syndrome has not been notified since 1990 but its risk persists with a recent increase in rubella notifications, a fall in school immunisation rates, a relatively low antenatal sero-positive rate among older Asian women born overseas and the trend towards giving birth at older ages. Effective immunisation programmes must be maintained, particularly in schools and for young children and migrant women.

Hearing impairment among 10-year-old children: metropolitan Atlanta, 1985 through 1987

The prevalence of hearing impairment among 10-year-old children in metropolitan Atlanta between 1985 and 1987 was evaluated. Hearing-impaired children were identified by reviewing records at public schools and health and social service agencies. The prevalence was 1.1 per 1000 and was slightly higher among Blacks and boys than among Whites and girls. The most common known causes of hearing impairment were meningitis (0.3 per 1000), genetic and hereditary conditions (0.2 per 1000), and congenital rubella syndrome (0.1 per 1000). For 55% of the children, the etiology of the hearing loss could not be determined. Most (74%) of the children were diagnosed after the age of 2, suggesting that methods of early identification need to be improved.

Seroepidemiology, morbidity and vaccination strategies against rubella infection. Eight years experience in Oltrepò Pavese

Selective rubella vaccination of schoolgirls in Italy started 14 years ago following the United Kingdom strategy that was adopted in 1970. The aims of this program were to eliminate the risk of rubella among women of childbearing age, encourage the acquisition of immunity by natural infection during early childhood and allow the vaccine-induced antibody production by the circulating virus. On the basis of this program, between 1982 to 1990, a prospective serosurvey for rubella antibody in the province of Pavia was performed. The results showed a decline in the overall seropositivity rate for rubella antibodies from 57.7% in 1982 to 41.9% in 1984 followed by a remarkable increase in 1985 (53.3%) and in 1987 (56.5%). This trend was confirmed by the number of cases reported to the local Public Health Service. The results of this study provide further evidence of the need to change the current selective immunization policy in order to obtain a significant reduction of risk of the infection in the population.

Rubella in the developing world

Before Gregg's historic observation [1] rubella was not considered to have clinical or epidemiological importance in any country. In the western world epidemics occurred at varying intervals but with little morbidity and apparently only minor complications. Despite confirmation of Gregg's findings from many quarters, it was not until the worldwide outbreaks in the 1960s that the aftermath of rubella infection in pregnancy was fully realized. As a result of the 1964 outbreak in New York City, more than 1000 children were born with congenital rubella syndrome (CRS) and over 300 pregnancies either aborted spontaneously or were terminated for rubella infection [2]. The number of children affected represented 1% of births in the city; if extrapolated to the whole country this gave an estimated total of 30000 cases of CRS. No such disasters have so far been reported from the developing world.

Evaluation of rubella immune status by three commercial enzyme-linked immunosorbent assays

Three commercial indirect enzyme-linked immunosorbent assays (ELISAs) (Enzygnost-Rubella, RUBELISA, and ORTHO Rubella) were evaluated for the determination of immune status by testing 1,090 serum specimens, 410 of which were from nonimmune patients. In comparison with the standard reference technique, the hemagglutination inhibition (HAI) test, the sensitivities of ORTHO Rubella (100%) and Enzygnost-Rubella (99.26%) were excellent, whereas the sensitivity of RUBELISA (95.60%) was marginally lower because of the inability of this assay to detect antibody in 22% of the serum specimens with HAI titers of 10 and 11% of sera with HAI titers of 20. The specificity of all three systems was greater than 97%. There was a linear correlation between mean ELISA values and increasing HAI titers (r greater than or equal to 0.94). Both ORTHO Rubella and Enzygnost-Rubella were shown to be suitable replacements for the HAI test, provided that an equivocal zone is incorporated in the ORTHO system and only unheated sera are used in the Enzygnost system.

The decline in congenital rubella syndrome in Western Australia: an impact of the school girl vaccination program?

Rubella vaccination became available in 1970 in Australia. In Western Australia (WA), a school girl vaccination program was well established by 1971. Mothers under 26 years of age in 1983 would have been eligible for this program and they constitute 40 per cent of WA births. Data on Congenital Rubella Syndrome (CRS) cases were obtained for years of birth 1968-83 inclusive to ascertain if there had been an impact of the program on the CRS rate. Epidemics of rubella occurred in 1970-71, 1974, and 1979-80. The CRS rate has fallen steadily; it did not rise during the 1979-80 epidemic and was less than one in each year after 1977. All CRS cases born since 1974 were to mothers too old to have been eligible for the program. The data suggest that the vaccination program is effective, but this cannot be proven until data become available on pregnancy terminations.

Rubella in teenagers: epidemiology and prophylaxis in Siena, Italy

Six hundred and fifty-three teenagers (aged 11-13 year) living in Siena and its surroundings (Tuscany, Italy) were the sample for serological screening intended to ascertain immunity to rubella. It was found that 324 of the teenagers (49.62%) lacked antibodies and, hence, were unprotected against the infection. Out of the 324 girls, 196 (around 3/5) were vaccinated using live vaccine. Post-vaccinal complications, with clinical signs of rubella infection, were recorded in almost one third of the vaccinees. Virus isolation from the blood was, in every case, not possible after either 10 or 30 days from vaccination. The serological findings, expressed in hemagglutination inhibition antibodies, could be summarized in the following way: (i) antibodies at low titre were found in only eight out of 184 girls (4.35%) ten days after vaccination; (ii) serological conversion was recorded in 187 out of 188 girls (99.47%) 30 days after vaccination; (iii) the titres were moderately high but much lower than those recorded for the natural infection. The results are discussed in the context of their implications for the strategies of rubella vaccination as far as the safety and the effectiveness of the vaccine are concerned, with emphasis on the duration of the protective immunity.