Burden of congenital rubella syndrome (CRS) in India: <Emphasis Type="Italic">A systematic review</Emphasis>

Background

Rubella, though a mild, vaccine-preventable disease, can manifest with severe teratogenic effects in the fetus labeled as congenital rubella syndrome (CRS) due to primary maternal rubella infection. Despite a reduction in disease burden of several vaccine-preventable diseases through childhood immunization, CRS continues to account for preventable severe morbidity including childhood blindness, deafness, heart disease, and mental retardation.

Objective

To conduct a systematic review to describe the prevalence of CRS and its contribution to major long-term handicaps in Indian population. Another objective was to estimate the susceptibility to rubella infection in Indian adolescent girls and women of reproductive age-group. We also explored strategies to decrease CRS in India by identifying the immunogenicity of rubella containing vaccines (RCV) in Indian children and women, as well as their coverage in India.

Methods

Publications reporting ‘CRS prevalence in general population as well as selected subgroups i.e., suspected intra-uterine infection, congenital ocular abnormalities, deafness, congenital heart disease, mental retardation, and congenital malformations’, ‘seroprevalence to rubella (IgG) amongst women and adolescents’, and ‘immunogenicity and coverage of RCVs’ in Indian population were retrieved through a systematic search. Primary databases employed were Medline through PubMed and IndMed, websites of the WHO, and UNICEF. No restrictions were applied in terms of study designs. The primary outcome measure was ‘congenital rubella syndrome’ (CRS) which was further categorized as ‘suspected CRS’ and ‘confirmed CRS’ as defined by World Health Organization (WHO).

Results

Comprehensive evidence about the true burden of CRS in India is not available. Almost all studies have been done in institutional/hospital set-ups and community-based studies are grossly lacking. There are no studies assessing the prevalence of CRS in general population. All studies have evaluated the CRS burden in symptomatic cohorts of children. 1–15% of all infants suspected to have intra-uterine infection were found to have laboratory evidence of CRS. About 3–10% of suspected CRS cases are ultimately proven to have confirmed CRS with the aid of laboratory tests. CRS accounts for 10–15% of pediatric cataract. 10–50% of children with congenital anomalies have laboratory evidence of CRS. 10–30% of adolescent females and 12–30% of women in the reproductive age-group are susceptible to rubella infection in India. RCVs are highly immunogenic in Indian adolescents and women. The coverage data of RCVs in India is not available. However, the coverage of MMR vaccine has been reported as 42%, 30% and 5% from Delhi, Chandigarh and Goa, respectively.

Conclusion

This systematic review identifies and explores factors associated with the prevalence of CRS in India. There is a need for urgent action in terms of revamping the national immunization policy and introduction of RCVs in the national immunization program. Active surveillance of rubella and CRS is needed to redress the burden of CRS in India.

     

Parenchymal calcification is associated with the neurological prognosis in patients with congenital rubella syndrome

Congenital rubella syndrome (CRS) results from maternal rubella virus infection in early pregnancy. Abnormal neuroimaging findings have been analyzed in a small number of CRS patients in the past; however, their clinical significance has been poorly addressed. Therefore, we have investigated the neuroimaging findings of 31 patients with CRS from previous studies. The most common finding was parenchymal calcification, which was observed in 18 of 31 patients (58.1%). A multivariable logistic regression model showed that it was associated with psychomotor or mental retardation (p = 0.018), suggesting that parenchymal calcification in CRS could be a prognostic factor.     

Estimating the burden of congenital rubella syndrome in Costa Rica, 1996-2001

BACKGROUND: The epidemiology of rubella in Costa Rica changed during recent decades, shifting the susceptible groups to the reproductive age. This study estimates the burden of congenital rubella syndrome (CRS) from 1996 to 2001 in this country. METHODS: Three methods to calculate CRS incidence were used. A retrospective search ("Observed cases") was conducted using hospital discharge records of children born from 1996 to 2001 with selected codes of ICD9 and ICD10 consistent with CRS and children <3 months of age with a positive serologic test for rubella IgM antibody at the National Children's Hospital (NCH). Cases were classified as either suspected, compatible or confirmed CRS and congenital rubella infection. "Expected" incidence of CRS was calculated using reported cases of rubella (women 15-45 years of age) and fertility rates, assuming CRS probability of 0.9 during the first trimester of pregnancy and 0.5 of asymptomatic rubella cases. "Estimated" CRS cases were calculated using incidence rates reported from modeling analysis during epidemic and endemic years. RESULTS: Of the 577 discharge charts reviewed and the 66 children reported as rubella IgM(+), 40 compatible CRS cases, 45 confirmed, and 4 with congenital rubella infection cases were identified. The range of annual incidence rate of CRS (per 1000 live births) was as follows: "Observed" = 0.00-0.33, "Expected" = 0.00-0.35 and "Estimated" = 0.5-1.5. Compared with the estimated number of CRS cases, only 27.2% of CRS cases were detected from the retrospective search and 10.1% would be expected when calculated using rubella reported cases. CONCLUSIONS: The under-detection of CRS cases using rubella reported cases in women of reproductive age and retrospective search of CRS reinforces the importance of suspecting CRS in the presence of a single compatible manifestation. Laboratory confirmation is indispensable to implement CRS elimination strategies and should be done in every suspected case.     

A Rubella Epidemic in Sasebo, Japan in 1957, with Various Complications

Though the rubella vaccination programme for adolescent girls was introduced in Japan in 1977, rubella epidemics have occurred repeatedly. Also in Sasebo, Japan in 1987, we experienced various complications as follows: encephalitis (five cases), meningitis (three), thrombocytopenic purpura (four), vascular purpura (four), hemolytic anemia (two), pneumonia (eight), protein-losing gastroenteropathy (one), multiple organ disorder with encephalitis, purpura, myocarditis, hepatic and renal dysfunction (one), and congenital rubella syndrome (CRS: three). Disorders ranging over multiple organs seem to occur in acquired as well as congenital rubella infection. The incidence of encephalitis was estimated to be 1: 1600 cases of rubella and two of five cases were apparently serious. Though the strategy for preventing rubella has been directed only against CRS, we should note the various and severe complications with acquired rubella infection, and should adopt two-stepped protection: vaccination of young children of both sexes and of adolescent girls.     

Congenital rubella syndrome after rubella vaccination in 1–4 weeks periconceptional period

Objective  To examine weather exposure to rubella vaccine during 1–4 wk periconceptional period can cause congenital rubella syndrome (CRS). Methods  This prospective study was performed in 60 pregnant women who received rubella vaccine inadvertently 1–4 wk pre or post conception. Time of conception was determined by last menstrual period (LMP) and first trimester sonography. In addition to gathering mother’s obstetric and demographic information, all neonates were evaluated for CRS signs by systemic physical examination and anti rubella IgG and IgM antibody titers in cord blood samples. Results  A total of 60 pregnant women with the median gestational age of 38 weeks were studied. The mean maternal age was 22 years and 58.3% of pregnancies were unintended. In 90% of mothers there were no post vaccination side effects (fever, lymphadenopathy, arthritis, arthralgia). None of the mothers had a history of drug abuse, smoking or teratogenic exposures. Mean neonatal weight was 3100grs and 6.7% of them were premature. No signs of CRS were found in the neonates based on systemic physical exam at birth and one month later. Mean value of cord blood anti rubella IgG titere was 148/28±67/26 lu/ml. cord blood anti rubella IgM was negative in all of the neonates. Conclusion  In this study inadvertent rubella vaccination 1–4 wk before and after conception did not cause CRS in neonates and according to all reasearches pregnancy termination is not indicated in these cases.     

Incidence, clinical features and estimated costs of congenital rubella syndrome after a large rubella outbreak in Recife, Brazil, 1999-2000

BACKGROUND: During 1998-2000, a large rubella outbreak was reported from Recife, the capital municipality of Pernambuco State, in northeastern Brazil. In 2002, a study was conducted to assess the burden of congenital rubella syndrome (CRS) after this outbreak. METHODS: To describe the rubella outbreak, we analyzed data available from the National Notifiable Disease System. A retrospective record review for CRS was conducted at 6 maternity hospitals where 53% of Recife's resident live births occurred during 1999-2000 and 1 tertiary health care center. Suspected CRS cases were infants with any manifestation of CRS or maternal infection during pregnancy. Standard international definitions for compatible and confirmed CRS cases were used. Direct CRS costs were based on reimbursements by the National Health System. RESULTS: From October 1998 to July 2000, Recife reported 681 confirmed rubella cases. The highest incidence of rubella was among children 5-11 years of age (5.4 per 1000 population). Forty-five suspected CRS cases were identified; 29 were clinically compatible and 2 were laboratory-confirmed. The average annual incidence of CRS was 0.9 per 1000 live births during 1999-2000. Overall costs for the first year follow-up were estimated at 61,824 US dollars in this cohort. CONCLUSIONS: High rubella vaccination coverage is required to prevent the severe congenital disabilities and high economic costs of CRS. Increased clinician awareness is critical for early CRS detection. Complete reporting is essential to evaluate the impact of vaccination programs and to document progress toward the goal of CRS elimination in the Americas by the year 2010.     

Incidence and Outcome of Acute Cardiorenal Syndrome in Hospitalized Children

Objectives

To determine the incidence, etiology and outcome of Cardiorenal syndrome (CRS) in hospitalized children.

Methods

A prospective cohort study was carried out in 242 children between 6 mo to 18 y of age hospitalized with primary cardiac, renal or any systemic disorder at a tertiary care center in India. The primary outcome was the development of CRS. Univariate and multivariate logistic regression analysis were performed to determine the risk of mortality secondary to CRS.

Results

Among 242 children, 67 (27.7%) children developed CRS and the rest 175 (72.3%) did not. Among those with CRS, 40.3%, 20.9%, and 38.8% had CRS-1, 3 and 5, respectively. Cardiac diseases leading to CRS were myocarditis (40.7%) followed by congenital heart disease (25.9%), rheumatic heart disease (18.5%), and dilated cardiomyopathy (7.4%); renal disease associated with CRS was acute glomerulonephritis (100%) and major systemic disorders leading to CRS were septicemia (53.8%), malaria (23.1%), scrub typhus (7.7%), and acute gastroenteritis (3.8%). The occurrence of CRS was associated with an increased risk of mortality (OR 6.3, 95% CI: 2.8, 14.1; p 0.000). A subgroup analysis revealed that children with CRS having acute kidney injury stage 2 and 3 also had a higher risk of mortality (p 0.001).

Conclusions

The incidence of CRS is quite high in children with cardiac, renal or systemic diseases and is associated with a significant risk of mortality. Children presenting with these illnesses should be monitored for the occurrence of CRS so that early intervention may reduce mortality.

     

Fetal risk associated with rubella vaccination during pregnancy

BACKGROUND: Costa Rica implemented a nationwide measles-rubella vaccination campaign among men and women (15-39 years old) in May 2001. A protocol was developed to follow-up the vaccinated women who were unknowingly pregnant, to determine the risk of congenital rubella syndrome (CRS) or congenital rubella infection only associated with the administration of the rubella vaccine RA27/3 during pregnancy. METHODS: To classify the prevaccination maternal immune status, a serum sample was taken at the initial evaluation to detect IgM and IgG rubella antibodies (enzyme-linked immunosorbent assay). All pregnancies were followed up and all newborns were evaluated. A cord serum sample of their children was taken at birth. We calculated odds ratio, OR (95% confidence interval, 95% CI) associated with miscarriage, stillbirth, prematurity, low birth weight, and the presence of defects compatible with CRS. RESULTS: The prevaccination immune status was established in 797 women and 1191 mother and child pairs were analyzed. Adjusted OR for miscarriage (OR = 0.60, 95% CI = 0.26-1.39), stillbirth (OR = 1.32, 95% CI = 0.10-16.81), prematurity (OR = 0.25, 95% CI = 0.03-2.39), low birth weight (OR = 0.25, 95% CI = 0.03-2.23) and defects compatible with CRS (OR = 1.09, 95% CI = 0.34-3.54) showed no association between immune and susceptible maternal status. There were no cases of CRS and no children were IgM positive. CONCLUSIONS: No adverse pregnancy outcome such as miscarriages or CRS was documented in women who were vaccinated and unknowingly pregnant. These results support RA27/3 rubella vaccine safety.     

Burden of congenital rubella syndrome after a community-wide rubella outbreak,Rio Branco,Acre, Brazil, 2000 to 2001

BACKGROUND: During 1999 and 2000 rubella outbreaks were reported in 20 of 27 states in Brazil, many among young adults. We investigated a large rubella outbreak in Rio Branco, Acre, in northwestern Brazil, where rubella vaccination targeting children 1 to 11 years old had been introduced in April 2000. Surveillance for congenital rubella syndrome (CRS) was initiated after the outbreak. METHODS: Suspected rubella cases were detected through active and passive surveillance. Confirmed rubella cases were patients with fever, rash and rubella-specific IgM antibodies. Suspected CRS cases were infants born with CRS-compatible defects or born to mothers with a history of rubella during pregnancy. Confirmed cases were infants with CRS-compatible defects and rubella-specific IgM antibodies. RESULTS: From April 1 to December 31, 2000, 391 confirmed rubella cases were reported. The incidence among persons ages 12 to 19 years (3.3 per 1000 population) was increased 3.7-fold relative to children ages 1 to 4 years (95% confidence interval, 2.4 to 5.8). Of 21 infants with suspected CRS cases, 17 (91%) were tested for rubella-specific antibodies, of whom 7 were IgM-positive and 5 had confirmed CRS. The peak incidence of confirmed CRS (4.3 per 1000) was in March 2001, 7 months after the outbreak peak, with an annualized incidence of 0.6 per 1000. CONCLUSIONS: Vaccination among school age children was insufficient to prevent a rubella outbreak among young adults that resulted in the occurrence of at least 5 cases of CRS. To prevent further cases of CRS, outbreak vaccination of young adults was conducted in November 2000 and among women ages 12 to 39 years in 2001 as part of a national campaign, with a coverage of 98% statewide.     

Rubella seroprevalence among Turkish adolescent girls living in Edirne, Turkey

This study was designed to estimate the rubella seroprevalence in unvaccinated Turkish adolescent girls in urban and rural areas of Edirne, and to create preventive strategies for congenital rubella syndrome (CRS). The sample, representing 12- to 17-year-old adolescent girls, consisted of 1,600 subjects selected from school lists by systematic and random sampling, which was matched by age and urban-rural residency strata proportional to the corresponding distributions in the Edirne population. For each participant, a questionnaire was completed and rubella-specific IgG antibodies were measured. After analysis of samples, seropositivity prevalence, equivocal and seronegative samples of adolescent girls in Edirne were determined as 93.1%, 0.6% and 6.3%, respectively. Data from the present study may indicate that 6.9% of adolescent girls have considerable risk for rubella infection during pregnancy. Eliminating rubella and CRS in Turkey will require national health service efforts, including vaccination of all adolescents and all susceptible women of childbearing age.     

Molecular epidemiology of rubella virus in Asia: Utility for reduction in the burden of diseases due to congenital rubella syndrome

BACKGROUND: Rubella is a mild disease mainly of infants, involving a rash and a fever. However, when women who have no immunity to rubella are infected during the early stage of pregnancy, their babies are often born with congenital rubella syndrome (CRS), which is characterized by a few disorders including deafness, cataracts and heart malformations. To prevent CRS, several strains of live attenuated rubella vaccine have been developed and introduced into immunization programs in many countries. In most Asian countries except Japan, Singapore and Taiwan, rubella remains uncontrolled, and the burden of diseases from CRS is high. In order to develop a control program to reduce the number of CRS cases in Asian countries, it is necessary to conduct a survey of rubella and CRS cases, and to then determine the genotype of the circulating rubella virus in each country. METHODS: Cases of rubella and CRS, based on national reporting systems or active surveillance in the Asian countries, are summarized. Sequences of the E1 gene of the virus isolates from the Asian countries were compared by phylogenic analysis. RESULTS: Recent studies of the molecular epidemiology of rubella virus worldwide revealed that there are two genotypes, and that genotype I is circulating almost worldwide, while genotype II is an Asian prototype restricted to the Asian continent. Genotype I viruses fall into a number of groups, some of which are geographically localized. Antigenically these two genotypes are cross-reactive and immunization with either virus results in immunity to all rubella viruses. DISCUSSION: The hypotheses that rubella virus has evolved on the Asian continent is proposed. The World Health Organization (WHO) has recognized that a rubella immunization program can be combined with the measles immunization program. Inclusion of rubella in the expanded program of immunization (EPI) of measles would be ideal in Asian countries, as it would be efficient and cost effective to administer one injection containing a three-combined vaccine (MMR). It would also be desirable given that WHO require laboratory tests to confirm the presence of measles or rubella as part of it's measles control project, because rubella is often misdiagnosed as measles.     

Chronic rhinosinusitis in young children differs from adults: a histopathology study

Objective

A histopathologic study of children with chronic rhinosinusitis (CRS) was undertaken to compare the sinus mucosa in pediatric and adult CRS.

Study design

CRS has been defined as persistent or recurrent sinusitis symptoms for ≥12 weeks despite conventional medical therapy, with abnormal computed tomography of the maxillary sinuses. Maxillary mucosal biopsies were obtained from pediatric CRS subjects for inflammatory cell and morphologic studies. Archival sinus mucosal tissues from adults with CRS were used as histologic controls. Sinus lavages were performed on children with and without CRS for microbiologic studies.

Results

Sinus mucosal biopsies were obtained from 19 children with CRS (median age, 3.0 years; range 1.4-8.2 years). Pediatric CRS biopsies, as compared with adult CRS controls, had a higher density of submucosal lymphocytes (median 469 versus 294 cells/mm² per 5 high-power fields [HPF]; P = .02), lower density of submucosal eosinophils (medians 13 versus 82 cells/mm² per 5 HPF; P = .01), thinner and more intact epithelium (P = .01 and .07, respectively), thinner basement membranes (P = .002), and fewer submucosal mucous glands (P = .004).

Conclusion

The sinus mucosa of young children with CRS has less eosinophilic inflammation, basement membrane thickening, and mucus gland hyperplasia characteristic of adult CRS.     

A randomized trial of the effectiveness of the neutropenic diet versus food safety guidelines on infection rate in pediatric oncology patients

1 Background

The neutropenic diet (ND) is prescribed to avoid introduction of bacteria into a host's gastrointestinal tract and reduce infection. Due to a lack of evidence to support the ND, there continues to be debate among pediatric oncologists regarding its usefulness. This prospective randomized controlled trial evaluated the difference in neutropenic infection rates in pediatric oncology patients randomized to Food and Drug Administration approved food safety guidelines (FSGs) versus the ND plus FSGs during one cycle of chemotherapy.

2 Procedure

Pediatric patients receiving cancer treatment with myelosuppressive chemotherapy were eligible. Neutropenic infection was the primary outcome and defined as (i) fever with neutropenia or (ii) hospital admission and treatment for clinical infection and neutropenia. The rate of neutropenic infection was compared with Student's t‐test for independent samples. Documented infections were identified by comprehensive chart review and compared between groups using a χ² test.

3 Results

: One hundred fifty patients were randomly assigned to FSGs (n = 73) or ND + FSGs (n = 77). The most common diagnoses were acute lymphoblastic leukemia (32%) and sarcoma (32%). There was no significant difference between the groups in the percentage of patients who developed neutropenic infection: FSGs 33% versus ND + FSGs 35% (P = 0.78). Patients randomized to ND + FSGs reported that following the diet required more effort than those on FSGs alone.

4 Conclusion

The ND offers no benefit over FSGs in the prevention of infection in pediatric oncology patients undergoing myelosuppressive chemotherapy and adherence requires more effort for patients and families. Institutions caring for children with cancer should consider replacing ND guidelines with FSGs.     

An epidemic of congenital rubella in Barbados

Rubella and congenital rubella syndrome (CRS) are preventable, but epidemics of rubella and CRS are not infrequent in the Caribbean and other developing countries. As a result of a surveillance system initiated after an epidemic of rubella in the Barbadian population in 1996, cases of CRS were identified and investigated. A total of seven cases of CRS were proven to be rubella IgM-positive. The infants were found to have a mean birthweight of 2587 g and a mean gestational age of 38 weeks. The clinical course, complications and outcome of those infants were documented and the cost of acute hospital care for each patient was also recorded. Cataracts in four infants, congenital heart disease in three and central nervous system abnormalities in five were the major clinical abnormalities. In four infants, two or more clinical systems were affected. The combined total hospital stay was 105 days (mean 15, range 0-44). A national effort to immunize all those at risk and a strict surveillance programme are essential to prevent future epidemics. This would lead to a significant reduction in the number of cases of rubella and CRS and could effect substantial savings in the national health budget.     

Study of Urinary Tract Infection and Bacteriuria in Neonatal Sepsis

Objective  

To determine magnitude of Urinary tract infection (UTI) in neonatal sepsis and to evaluate bacteriuria as indicator of neonatal urinary tract infection for use in resource limited settings.     

History of parvovirus B19 infection is associated with silent cerebral infarcts

1 Background

The relationship between silent cerebral infarcts (SCIs) and history of parvovirus B19 (B19V) has not been systematically evaluated. As an ancillary study from the Silent Cerebral Infarct Trial (SIT) (NCT00072761), we tested the hypothesis that a history of B19V infection is associated with an increased prevalence of SCIs in children with sickle cell anemia.

2 Procedure

We used a retrospective cross‐sectional cohort study design; each participant underwent a brain magnetic resonance imaging (MRI) scan and medical record review for prior B19V infection (n = 958).

3 Results

SCI was present in 30% (287 of 958) of participants and 17% (165 of 958) had a history of B19V infection. Based on prior evidence that low baseline hemoglobin (Hgb) levels are associated with increased odds of SCI, Hgb levels were divided into tertiles (<7.6 g/dl, ≥7.6–≤8.5 g/dl, ≥8.6 g/dl) and multivariable analysis was used to determine the relationship between the joint effect of prior B19V infection, Hgb levels, and SCI. Prior B19V infection and the lowest Hgb tertile were associated with increased risk of SCI (odds ratio [OR] 2.12; 95% CI, 1.17–3.84; P = 0.013); no prior B19V infection and the highest Hgb tertile were associated with a decreased risk (OR 0.56; 95% CI, 0.38–0.84; P = 0.004).

4 Conclusions

Efforts to decrease the incidence of B19V infection, such as the development of a B19V vaccine, may decrease SCI prevalence.     

Do pediatric emergency departments pose a risk of infection?

Background  

There is no data documenting the existence of a risk of infection transmission in ambulatory healthcare settings but concern remains. Our objective was to determine the risk of infection associated to a pediatric Emergency Department (ED) visit and the predictors of infection in children aged 5 years and less.     

Long-term Seroprotection Rates Following Second Dose of Measles as MMR Vaccine at 15 months in Indian Children

Objective

To find out seropositivity rates at 4-6 and 9-12 years of age; among those who received one-dose measles at 9 months and one-dose MMR at 15 months of age.

Methods

80 healthy children (53 males) at 4-6 or 9-12 years of age, attending outpatient department for vaccination were enrolled. Antibody titers were estimated using commercially available quantitative-IgG ELISA kits.

Results

The seropositivity rates against measles, mumps, rubella were 80% (40/50), 86% (43/50), and 96% (48/50), respectively at 4-6 years, and 83.3% (25/30), 96.7% (29/30) and 96.7% (29/30), respectively at 9-12 years of age.

Conclusion

Single dose of rubella vaccine seems to provide adequate long-term protection; however, measles vaccine requires more doses for similar protection.

     

Zinc Supplementation in Severe Acute Lower Respiratory Tract Infection in Children: A Triple-Blind Randomized Placebo Controlled Trial

Objective  

To evaluate the efficacy of zinc supplementation on duration of illness in children with severe acute lower respiratory tract infection (ALRTI).     

The contribution of single antigen measles, mumps and rubella vaccines to immunity to these infections in England and Wales

Objective

To obtain information on the use of single antigen measles, mumps and rubella vaccines to improve estimates of population immunity and help predict outbreaks.

Design

We requested information from providers of single antigen vaccines and from the Medicine and Healthcare products Regulatory Agency on requests for importation of single antigen measles and mumps vaccines.

Setting

England and Wales.

Main outcome measures

Number of doses of single measles, mumps and rubella vaccine, by age of child (in months), year given and area of residence, and number of children who have received all three single vaccinations.

Results

Of 27 providers identified, 13 held single site clinics: nine were individual general practitioners and five held clinics at multiple sites. Data were received from 9/27 (33%) providers operating 40/74 (54%) clinic sites. We received information on 60 768 vaccinations administered by single vaccine providers and 269 917 doses requested for importation. For children born in 2001/2002, the minimum estimates for the proportion who received single measles vaccine are 1.7% in 2001 and 2.1% in 2002, with a reasonable maximum estimate of 5.6% over the 2 years. For single mumps vaccine, the minimum estimates are 0.3% in 2001 and 0.02% in 2002, with a maximum estimate of 4.0%.

Conclusion

The contribution of single vaccines to immunity is small in comparison to that of the combined measles, mumps and rubella vaccine (MMR). For recent birth cohorts this contribution could increase routine coverage for measles‐containing vaccines by around 2%, still below the level of immunity required to sustain elimination.