Effect of selective vaccination on rubella susceptibility and infection in pregnancy.

The effect of school and adult vaccination on susceptibility to rubella in women of childbearing age was assessed in the Manchester area, where the population attending antenatal clinics is over 40 000 a year. Between 1979 and 1984 the proportion susceptible fell from 6.4% to 2.7%. In 1984, 4.2% of nulliparous women were susceptible compared with 1.4% of women in their second or subsequent pregnancy. Eighty five per cent of pregnant women screened and found to be non-immune were vaccinated post partum before leaving hospital. Requests for prevaccination screening of non-pregnant women increased in response to a national campaign and at the time of local outbreaks of rubella but only two thirds of those found to be nonimmune were subsequently vaccinated. During 1983 and 1984 infection was confirmed in 57 pregnant women--2% of those non-immune. Selective vaccination has reduced susceptibility to rubella in the childbearing population, but it is suggested that mass vaccination of children of both sexes should be added to the existing policy to control circulation of wild rubella virus and reduce the risk of infection to pregnant women who remain susceptible.     

Role of the occupational health service in screening and increasing the uptake of rubella immunisation.

An occupational health department in a district general hospital in Newcastle upon Tyne screened 487 women of childbearing age for rubella immunity who were prospective employees and whose immunity state was unknown. Ninety per cent of these women were immune. Of the 51 who were found to be susceptible, 29 accepted vaccination.     

Immunity to rubella in women of childbearing age in the United Kingdom.

In the first three years of a surveillance scheme for susceptibility to rubella in women aged 15-44 the results of over 1.3 million serological tests were collected by 80 laboratories throughout the United Kingdom. Seventy eight per cent of the results, or an average of 340,000 a year, were from pregnant women, so that just under half of all pregnant women in the United Kingdom were reported on. Eighteen per cent of results were from women tested before vaccination and the remainder were from diagnostic and other tests. Pregnant women showed an overall downward trend in susceptibility to rubella (from 4.2% at the beginning of 1984 to 3.0% at the end of 1986), and a similar decline was seen in the two other categories. Regional data showed a significant negative correlation between the proportion of pregnant women aged 15-19 who were susceptible to the virus and rate of uptake of vaccine in 14 year old schoolgirls. Women aged 25-29 were least susceptible. This form of laboratory surveillance is feasible and representative; it should be continued to monitor the effect of introducing the measles, mumps, and rubella vaccine.     

Immunity to rubella in prepubertal girls in Prince Edward Island.

A survey of rubella immunity was conducted among prepubertal girls in Prince Edward Island. Of the 431 girls enrolled in grade 4 in a random sample of schools 83% had a school record of having been vaccinated after their first birthday. A screening test of finger-prick samples revealed that 95% of the girls with a written history of vaccination after their first birthday were immune, 79% of those vaccinated before their first birthday or for whom the date of vaccination was uncertain were immune, and 40% of unvaccinated girls were immune. Of the 49 susceptible girls 43 were vaccinated; all but 2 were found to be immune on retesting. The findings support the recommendation of the National Advisory Committee on Immunization to vaccinate all prepubertal girls without a written history of rubella vaccination after their first birthday.     

Rubella antibody titres and immunization status in a family practice.

Rubella vaccination status and immunity to rubella were studied in 230 "active patients" aged 8 to 22 years in a teaching family practice by means of a chart review and measurement of the rubella antibody titre in a blood sample. Of the 200 patients who submitted a blood sample 161 (80%) were found to be immune, having a rubella hemagglutination-inhibiting antibody titre of 1:16 or greater. Log linear analysis showed that immunity to rubella was independent of a history of rubella, and that 94% of the vaccinated patients versus 74% of the unvaccinated patients (a significant difference; P = 0.007) were immune. In retrospect we estimated that 80% of the study group were protected at the start of the study. After surveillance and follow-up, with vaccination of 27 of the 39 patients identified as susceptible to rubella, this estimated proportion increased to 90%. The study showed that there is nothing to be gained by asking about a history of rubella but that vaccination against this disease is increasing among children aged 5 to 9 years.     

Prevention of congenital rubella.

The vaccine of choice for rubella vaccination is considered to be RA 27/3, based on frequency of side effects, duration of immunity, antigenic potential and rate of reinfection by wild virus. The most appropriate individuals to be vaccinated are prepubertal schoolgirls and susceptible members of other high-risk groups, and a nationwide immunization program is suggested. Premarital determination of rubella-immune status should be mandatory for all women of childbearing age. A favourable cost/benefit ratio for rubella vaccination seems highly probable. The use of a rubella "fact sheet" to provide education and information for those at risk is strongly recommended.     

Rubella screening and immunisation of schoolgirls: results six to seven years after vaccination.

A long term follow-up study was carried out of girls given RA27/3 or Cendehill rubella vaccine in their 13th-14th year compared with a group of girls who had been found to be naturally immune at the age. A high proportion of the girls in all groups had persistent rubella antibody six to seven years after inclusion in the study, although some of these would have been considered to be susceptible to rubella by methods currently in use for screening for rubella antibody. Great care should be taken in interpreting the efficiency of the schoolgirl immunisation policy in the United Kingdom; women in their childbearing years who may have received vaccine but are found by a screening test to be seronegative should be retested by a more sensitive procedure before a final report is made.     

Can we prevent an increase in the incidence of congenital rubella syndrome in the next decade?

The immunity to rubella of 115 girls aged 10 to 14 years was tested in 1978. The proportion of girls found to be immune was 80%, similar to rates in the prevaccination era. Nearly half of the immunity was from documented vaccination, and the other half was presumably from infection with wild rubella virus. The vaccination failure rate was 12%. Because of declining immunity to rubella of women of child-bearing age, detecting low levels of immunity in these women is becoming increasingly important. Immunization of 12- to 15-month-old children has not been effective. Vaccinating all girls 10 to 12 years old would likely be the most effective method of preventing an increase in the incidence of congenital rubella syndrome in the next decade.     

Evaluation of rubella screening in pregnant women

BACKGROUND: The rationale for rubella vaccination in the general population and for screening for rubella in pregnant women is the prevention of congenital rubella syndrome. The objective of this study was to evaluate the effectiveness of the prenatal rubella screening program in Quebec. METHODS: A historical cross-sectional study was designed. Sixteen hospitals with obstetric services were randomly selected, 8 from among the 35 "large" hospitals in the province (500 or more live births/year) and 8 from among the 50 "small" hospitals (fewer than 500 live births/year). A total of 2551 women were randomly selected from all mothers of infants born between Apr. 1, 1993, and Mar. 31, 1994, by means of stratified 2-stage sampling. The proportions of women screened and vaccinated were ascertained from information obtained from the hospital chart, the physician''s office and the patient. RESULTS: The overall (adjusted) screening rate was 94.0%. The rates were significantly different between large and small hospitals (94.4% v. 89.6%). Five large hospitals and one small hospital had rates above 95.0%. The likelihood of not having been screened was statistically significantly higher for women who had been pregnant previously than for women pregnant for the first time (4.8% v. 1.4%; p < 0.001). Of the 200 women who were seronegative at the time of screening (8.4%), 79 had been vaccinated postpartum, had a positive serological result on subsequent testing or did not require vaccination, and 59 had not been vaccinated postpartum; for 62, subsequent vaccination status was unknown. INTERPRETATION: Continued improvement in screening practices is needed, especially in small hospitals. Because vaccination rates are unacceptably low, it is crucial that steps be taken to address this issue.     

Rubella immunity in pregnant women in a north London practice.

Congenital malformations due to rubella embryopathy are preventable. All women embarking on pregnancy should be immune and know that they are immune to rubella to guard against the risk of contracting the disease during pregnancy. A previous history of clinical rubella or rubella vaccination is not reliable, and women should be screened for antibodies when possible before planning to conceive, and particularly before a first pregnancy. As general practitioners committed to the practice of prevention, we should undertake rubella screening for all our women patients before they conceive. This could easily be incorporated into our contraceptive services. We will be greatly helped if family planning clinics adopted a policy of screening for rubella antibodies, always remembering that good documentation and communication will avoid duplication and confusion and reduce costs.     

Absence of cell-mediated immunity to rubella virus 5 years after rubella vaccination.

The long-term effectiveness of rubella vaccination in childhood is particularly important because the ultimate goal of immunization is the prevention of infection during pregnancy. Of 25 healthy children tested 4 to 5 years after rubella vaccination, 19 showed no evidence of cell-mediated immunity (CM) to rubella virus despite the presence of hemagglutination-inhibition or complement-fixation antibodies or both. Twenty-two of 25 seropositive, naturally infected young adults showed evidence of CMI. These results indicate that fetuses of women who have been vaccinated against rubella may not be protected against damage by wild rubella infection during the pregnancy, when CMI is physiologically depressed.     

Avidity of immunoglobulin G to rubella virus in post-vaccination and post-infection immunity

Comparative evaluation of avidity of IgG to rubella virus in vaccinated persons, in patients with rubella or other exanthematous illness, and in healthy persons revealed similar patterns in post-vaccination and post-infection immunity. Virus specific low avidity IgG (index of avidity < or =30%) were detected in patients with rubella during 7 weeks after symptoms appeared as well as in vaccinated persons which were tested 6 weeks after vaccination. Low avidity antibodies in sera were detected in 96% of patients with rubella and in 75% of vaccinated persons which were not immune before immunization. Live attenuated vaccines Ervevax, Priorix, and MMR-II had similar ability to induce low avidity IgG to rubella virus. Increase of low avidity antibodies concentration was noted after immunization of children with low levels of antibodies before vaccination. After immunization of persons with high avidity antibodies in serum, index of avidity remained above threshold. Anamnestic high avidity IgG (index of avidity 51-100%) were detected in majority of immune healthy persons (96.4%) as well as in patients with exanthematous illnesses not related to rubella infection (93.6%). ELISA test-systems for detection of low avidity IgG to rubella virus allow to obtain reliable information about seroconversion rate and characteristics of immune response in vaccines. Detection of low avidity IgG in serum obtained 5-6 weeks after immunization points to primary immune response, whereas identification of high avidity antibodies reveals already immune persons.     

Simulations of rubella vaccination strategies in China

Many infants whose mothers have rubella infections during their first trimester of pregnancy have birth defects called congenital rubella syndrome (CRS). China does not routinely vaccinate against rubella in the public sector, but may need to start as its 'one child per couple' policy changes the population age distribution and the dynamics of rubella epidemiology, so that the incidence of rubella in pregnant women increases. Computer simulations with demographic transitions and rubella transmission dynamics predict that, with no or limited rubella vaccination, CRS incidence in China in the 30 years after 2020 will be more than twice the level in 2005. Comparisons of rubella vaccination strategies using computer simulations show that routine vaccination of over 80% of 1-year-old children would be effective in reducing total CRS cases in 2005-2051 and eliminating rubella in China by 2051. Routine immunizations at higher levels and the addition of early mass vaccinations of 2-14-year-old children and women of childbearing ages would further reduce total CRS cases and speed up the elimination of rubella.     

Fetal infection after maternal reinfection with rubella: criteria for defining reinfection.

Five cases of asymptomatic maternal reinfection with rubella are described that occurred in England and Wales during 1985-8 and resulted in intrauterine infection. The criteria for diagnosing reinfection are described. In four cases the rubella contact was with the woman''s own children. Two women had therapeutic abortions, rubella virus being recovered from the products of conception, and three were delivered of infants with congenitally acquired disease. Though the risks associated with maternal reinfection with rubella are very small and being measured in a prospective study, it is hoped that the recently introduced augmented programme of rubella vaccination will reduce rubella in the community and therefore this small risk still further.     

Rubella Epidemic in a Maternity Unit

Four cases of rubella, the last confirmed by laboratory tests, occurred among the nurses of a large obstetric unit. Immediate measures were taken to prevent the spread of the infection to pregnant patients and staff, and none was in fact infected.Persons susceptible to rubella and who become infected may pose a real danger to women in early stages of gestation during the incubation period. We recommend that the immune status of medical and nursing personnel working in obstetric departments should be ascertained serologically, and that rubella vaccine should be offered to those who are susceptible.     

Swedish experience of two dose vaccination programme aiming at eliminating measles,mumps, and rubella.

In 1982 a two dose regimen was introduced in Sweden for the combined vaccination against measles, mumps, and rubella of children aged 18 months and 12 years. Since 1977 about half of the preschool children were vaccinated against measles annually, and since 1974 about 80% of 12 year old girls were vaccinated against rubella. During the period 1982 to 1985 90-93% of the eligible age cohorts of 18 month old children and 88-91% of the 12 year old children were immunised with the new combined vaccine. A study in 1982 of about 140 18 month old children who were nearly all seronegative before vaccination showed that 96%, 92%, and 99% seroconverted against measles, mumps, and rubella, respectively. A second study was carried out in 1983 of 247 12 year old children, of whom 11% lacked antibodies to measles, 27% to mumps, and 45% to rubella. This showed seroconversion in 82% and 80% against measles and mumps, respectively, and all children seroconverted against rubella. In the latest study in 1985 of 496 12 year olds 9% and 13% were seronegative against measles and mumps before vaccination, and 41% against rubella. Of these, 88% seroconverted to measles and 80% to mumps, and all converted to rubella when sera were tested by the haemolysis in gel method. After a neutralisation test against measles as well all children showed immunity to the disease. A low incidence of measles and declining figures for mumps and rubella were reported in 1984 to 1986. An outbreak of rubella during 1985 affected mainly boys in age cohorts in which only the girls had been vaccinated during the 1970s.     

Surveillance of antibody to rubella virus in Grampian: closing the immunity gap.

OBJECTIVES--To identify causes for the continuing deficit of rubella immunity in women of childbearing age with a view to further reducing the risk of the congenital rubella syndrome. DESIGN--A questionnaire was sent to the general practitioner and a laboratory follow up study conducted in a one year cohort of women found on screening to have inadequate protection against rubella. SETTING--Virus laboratory of the department of medical microbiology, Aberdeen, serving the health board areas of Grampian, Orkney, and Shetland. PATIENTS--239 women whose concentration of antibodies to rubella virus was either absent or below standard (15,000 IU/l) and whose general practitioner could be contacted to supply a history of infection, immunisation, pregnancy, and antibody testing. MAIN OUTCOME MEASURES--Whether rubella vaccination was given and whether those vaccinated were tested for seroconversion. RESULTS--Only 122 (55%) of the women for whom information was available received the recommended vaccine; only 74 (61%) of these were tested for seroconversion. Oversight was the reason given for not vaccinating 64 (65%) of the women who remained at risk. Women who were pregnant when tested were significantly less likely to receive vaccine (odds ratio 3.36) than women who were not pregnant, and even if vaccinated were less likely to have a follow up antibody test (odds ratio 1.94). CONCLUSION--Once women are identified as being unprotected against rubella they are often overlooked and not vaccinated. Prompting mechanisms aimed at general practitioners, such as the one recently set up in Grampian, should reduce the immunity gap and help to eradicate rubella in pregnancy.     

Congenital rubella in babies of south Asian women in England and Wales: an excess and its causes.

The incidence of congenital rubella was found to be 2.3 times higher in Asian than non-Asian births in England and Wales. This was attributed in part to higher susceptibility to rubella in Asian than non-Asian women, as shown by antenatal serological data from public health laboratories in Leeds, Luton, and Manchester. Examination of the ethnic origin of pregnant women requesting laboratory testing after contact with rubella or rash and of women with laboratory confirmed rubella in pregnancy also suggested that the disease was being underdiagnosed in pregnant Asian women. Failure to prevent congenital rubella by termination of infected pregnancies may therefore contribute to the increased incidence of the syndrome in Asians. Health education programmes about the dangers of rubella in pregnancy and of the need for vaccination can readily be promoted in the Asian community through existing ethnic organisations. Protection of other ethnic minorities likely to be at similar increased risk may require a vaccination programme aimed at national elimination of rubella.     

Increase in congenital rubella occurrence after immunisation in Greece: retrospective survey and systematic review

ObjectiveTo describe the events leading to the epidemic of congenital rubella syndrome in Greece in 1993 after a major rubella epidemic.DesignRetrospective survey and systematic review.SettingGreece (population 10 million), 1950-95.SubjectsChildren, adolescents, and women of childbearing age.ResultsAround 1975 in Greece the measles, mumps, and rubella vaccine started being given to boys and girls aged 1 year without policies to attain high vaccination coverage and to protect adolescents and young women. During the 1980s, vaccination coverage for rubella remained consistently below 50%, and the proportion of pregnant women susceptible to rubella gradually increased. In 1993 the incidence of rubella in young adults was higher than in any previous epidemic year. The epidemic of congenital rubella that followed, with 25 serologically confirmed cases (24.6 per 100 000 live births), was probably the largest such epidemic in Greece after 1950.ConclusionsWith low vaccination coverage, the immunisation of boys and girls aged 1 year against rubella carries the theoretical risk of increasing the occurrence of congenital rubella. This phenomenon, which has not been previously reported, occurred in Greece.