Epidemiological characteristics of rubella and congenital rubella syndrome in the 2012-2013 epidemics in Tokyo, Japan

Vascular cutaneous manifestations of COVID-19 and RNA viral pathogens: a systematic review

BACKGROUND

COVID-19, the widely recognized and highly contagious respiratory tract infection, has had a substantial impact on the field of dermatology since its emergence in 2019. SARS-CoV-2, the causative virus of COVID-19, is classified as an RNA virus. Various skin-related symptoms have been reported in patients with COVID-19, most notably the distinctive purple-red acral rash resembling chilblain lesions, commonly referred to as 'COVID toe'; similarly, skin-related symptoms have been observed in connection with other RNA viruses.

OBJECTIVES

To explore the relationship between RNA viruses and their associated vascular cutaneous manifestations vs. those observed in patients infected with SARS-CoV-2.

METHODS

A systematic literature review was conducted using PubMed and medical subject heading terms related to RNA viruses and related skin manifestations.

RESULTS

In total, 3994 patients diagnosed with COVID-19 presenting with skin rashes were included. Chilblain-like lesions were most frequently observed (30.2%), followed by erythematous maculopapular/morbilliform rashes (9.1%) and urticarial rashes (4.7%). Of 8362 patients diagnosed with RNA viruses, more than half of the skin findings reported were erythematous/maculopapular/morbilliform rashes (52.3%), followed by unspecified (11.3%) and purpuric rashes (10.6%).

CONCLUSIONS

When comparing RNA viral infections with COVID-19 infection, we observed similarities in the reported skin manifestations and their presumed pathways, with many implicated in the proinflammatory response. Owing to the wide range of cutaneous symptoms associated with RNA viruses and our currently limited understanding of the underlying mechanisms, additional research is warranted to investigate the pathology behind viral-induced skin lesions.

A Study Prevalence of Congenital Rubella Syndrome Cases Before and After Rubella Vaccination Campaign

Rubella is a vaccine-preventable disease and is the leading cause of congenital disabilities. This study was performed to identify the congenital rubella syndrome (CRS) patients before and after the Rubella Vaccination Campaign in the Outpatient Unit of the Audiology Department at Dr. Soetomo General Hospital Surabaya. This was a descriptive study that used secondary data from a CRS surveillance case investigation form and medical records from 2015 to 2020 at Dr. Soetomo Hospital. A total of 346 suspected CRS cases were included in this study. According to the final classification, 145 (41.9%) patients had clinical CRS, 65 (18.8%) had confirmed CRS, and 136 (39.3%) had discarded CRS. The majority of the suspected cases were in the < 1-month age group (27.4%). Hearing loss was the most prevalent symptom in both the pre and post-rubella vaccination campaign (RVC) introduction periods campaign among groups. A patient with suspected CRS clinical signs.

Crystal structure of the Rubella virus protease reveals a unique papain-like protease fold

Rubella, a viral disease characterized by a red skin rash, is well controlled because of an effective vaccine, but outbreaks are still occurring in the absence of available antiviral treatments. The Rubella virus (RUBV) papain-like protease (RubPro) is crucial for RUBV replication, cleaving the nonstructural polyprotein p200 into two multifunctional proteins, p150 and p90. This protease could represent a potential drug target, but structural and mechanistic details important for the inhibition of this enzyme are unclear. Here, we report a novel crystal structure of RubPro at a resolution of 1.64 Å. The RubPro adopts a unique papain-like protease fold, with a similar catalytic core to that of proteases from Severe acute respiratory syndrome coronavirus 2 and foot-and-mouth disease virus while having a distinctive N-terminal fingers domain. RubPro has well-conserved sequence motifs that are also found in its newly discovered Rubivirus relatives. In addition, we show that the RubPro construct has protease activity in trans against a construct of RUBV protease–helicase and fluorogenic peptides. A protease–helicase construct, exogenously expressed in Escherichia coli, was also cleaved at the p150–p90 cleavage junction, demonstrating protease activity of the protease–helicase protein. We also demonstrate that RubPro possesses deubiquitylation activity, suggesting a potential role of RubPro in modulating the host's innate immune responses. We anticipate that these structural and functional insights of RubPro will advance our current understanding of its function and help facilitate more structure-based research into the RUBV replication machinery, in hopes of developing antiviral therapeutics against RUBV.

Rubella

Rubella is an acute illness caused by rubella virus and characterised by fever and rash. Although rubella is a clinically mild illness, primary rubella virus infection in early pregnancy can result in congenital rubella syndrome, which has serious medical and public health consequences. WHO estimates that approximately 100 000 congenital rubella syndrome cases occur per year. Rubella virus is transmitted through respiratory droplets and direct contact. 25-50% of people infected with rubella virus are asymptomatic. Clinical disease often results in mild, self-limited illness characterised by fever, a generalised erythematous maculopapular rash, and lymphadenopathy. Complications include arthralgia, arthritis, thrombocytopenic purpura, and encephalitis. Common presenting signs and symptoms of congenital rubella syndrome include cataracts, sensorineural hearing impairment, congenital heart disease, jaundice, purpura, hepatosplenomegaly, and microcephaly. Rubella and congenital rubella syndrome can be prevented by rubella-containing vaccines, which are commonly administered in combination with measles vaccine. Although global rubella vaccine coverage reached only 70% in 2020 global rubella eradiation remains an ambitious but achievable goal.

Temporary Fertility Decline after Large Rubella Outbreak, Japan

Japan experienced 2 large rubella epidemics in 2004 and 2012–2014. Because of suboptimal immunization levels, the country has been experiencing a third major outbreak during 2018–2020. We conducted time series analyses to evaluate the effect of the 2012–2014 nationwide rubella epidemic on prefecture-level natality in Japan. We identified a statistically significant decline in fertility rates associated with rubella epidemic activity and increased Google searches for the term “rubella.” We noted that the timing of fertility declines in 2014 occurred 9–13 months after peak rubella incidence months in 2013 in 4 prefectures with the highest rubella incidence. Public health interventions should focus on enhancing vaccination campaigns against rubella, not only to protect pregnant women from infection but also to mitigate declines in population size and birth rates.

Persistence of anti-rubella immunoglobulin G antibody titers in young adults involved in a short-term periodic immunization in Japan

In Japan, several rubella outbreaks in adults have erupted due to insufficient immunity against rubella virus (RUBV). Although selective immunization is being promoted in addition to a routine rubella vaccine program as a rubella eradication strategy, serosurveillance against RUBV needs to be implemented in the generations corresponding to the transition period of vaccination. In this study, a survey of anti-rubella immunoglobulin G (IgG) antibody titers was conducted among young adults involved in the transitional periods of the routine rubella vaccine program. Serosurveillance was performed in 370 healthy young adults aged 18-20 years, and their serum samples were analyzed using an enzyme immunoassay to determine rubella-specific IgG antibody titers. Although multiple regression analysis revealed significant differences only in medical history, more than 90% of participants exhibited seropositivity, excluding those who received single-dose vaccine alone. Based on elapsed periods after the last vaccination, rubella-specific IgG antibody titers in less than a 6-year period were higher compared to that in the more than 10-year period. Although almost all study participants in the transitional period had seropositivity, the results may indicate that the persistence of seropositivity is related to past rubella outbreaks.

Population-based study of a free rubella-specific antibody testing and immunization campaign in Chiba city in response to the 2018-2019 nationwide rubella outbreak in Japan

Japan has not been able to eliminate rubella; as a result, the large rubella epidemic has occurred. Considering the complicated history of the vaccine policy in Japan, some susceptible populations became infected with rubella, resulting in an outbreak. We conducted a large serosurveillance against rubella in Chiba city after initiating free rubella-specific antibody testing and an immunization campaign during 2018-2019. The total number of rubella specific antibody tests that was conducted in the nationwide campaign and Chiba city original campaign was 8277 and 6104, respectively. The proportion of participants with an antibody titer of ≤1:16 using the hemagglutination inhibition (HI) test was higher in those in their 20-30s. On the contrary, the proportion of participants with an antibody titer of <1:8 using the HI test was higher in men in their 40-50s. This discrepancy possibly reflects the complicated history of the vaccine policy. The number of participants in the nationwide immunization campaign in this city was 1517, whereas that in the Chiba city campaign was 3607. The Chiba city campaign was effective against women in their 20-30s (child-bearing generation); however, the nationwide campaign was not sufficiently effective against men in their 40-50s because many workers were did not visit medical facilities to receive the measles-rubella vaccine.

Rubella outbreak among workers in three small- and medium-size business establishments associated with imported genotype 1E rubella virus-Shizuoka, Japan, 2015

On 12 February 2015, a local health department (LHD) in Shizuoka prefecture identified two reported rubella cases in its jurisdiction as employees of the same company. As other employees at the company resided both inside and outside of the health department's jurisdiction, it began collaborating with two additional LHDs and the National Institute of Infectious Diseases to investigate and respond to the outbreak, which subsequently identified cases in two additional companies. We obtained epidemiological, clinical, and outbreak response information from the national epidemiological surveillance of infectious disease system's database, the local health departments, and the associated companies. One specimen for genetic sequencing was collected from each of the three companies. The outbreak included a total of twenty-five cases, with seventeen confirmed and eight probable cases from three companies. Among them, 24 (96%) were male, 22 (88%) were employees of one company (Company X), and none had rubella vaccination history. The median age was 45 years (interquartile range: 40-51). Epidemiological information did not reveal the source of infection nor transmission route. All rubella viruses sequenced from the three specimens were classified into genotype 1E. The nucleotide sequences in the 739 bp-window region were completely identical in two specimens, with only one nucleotide difference in the third specimen. According to phylogenetic analysis, these strains were closely related to the Southeast and East Asian lineage. This rubella outbreak at three companies, ranging in size from small- to medium-size, in Japan occurred among unvaccinated employees aged at least 30 years, most of whom were male. Virologic analyses suggest all cases were infected with the same viral strain imported from Southeast Asia. Similar to these companies, most employees at small- and medium-size businesses in Japan are males with no vaccination history for rubella, which poses a serious risk for associated cases of congenital rubella syndrome (CRS).

Comparing catch-up vaccination programs based on analysis of 2012-13 rubella outbreak in Kawasaki City, Japan

During the 2012–13 rubella outbreak in Japan, local governments implemented subsidy programs for catch-up vaccination to mitigate the rubella outbreak and prevent congenital rubella syndrome (CRS). In most local governments, to prevent CRS, eligible persons of the subsidy program were women who were planning to have a child and men who were partners of pregnant women. On the other hand, in Kawasaki City, unimmunized men aged 23–39 years were additionally included in the eligible persons, because they were included in an unimmunized men group resulting from the historical transition of the national routine vaccination in Japan. The number of rubella cases in the city decreased earlier than that in the whole Japan. First, in order to estimate the effect of the catch-up vaccination campaign in Kawasaki City on the epidemic outcome, we performed numerical simulations with a Susceptible-Vaccinated-Exposed-Infectious-Recovered (SVEIR) model incorporating real data. The result indicated that the catch-up vaccination campaign showed a beneficial impact on the early decay of the rubella cases. Second, we numerically compared several different implementation strategies of catch-up vaccinations under a fixed amount of total vaccinations. As a result, we found that early and intensive vaccinations are vital for significant reduction in the number of rubella cases and CRS occurrences. Our study suggests that mathematical models with epidemiological and social data can contribute to identifying the most effective vaccination strategy.

Congenital Rubella Syndrome profile of audiology outpatient clinic in Surabaya, Indonesia

Congenital Rubella Syndrome (CRS) consists of hearing impairment, ophthalmology abnormalities, and congenital heart disease in children, resulting from rubella infection during pregnancy. Rubella vaccine has been implemented as national immunization program in Indonesia since 2017, and needed to be evaluated. This study aimed to report the CRS patients' profile of Audiology Outpatient Clinic in Surabaya. A descriptive study from patient's medical record was conducted in Dr. Soetomo Hospital Surabaya from January 2016 to December 2017. CRS was categorized using World Health Organization classification. Suspected infants with CRS burden were assessed by Otoacoustic Emission and rubella antibody test. Ninety five infants suspected with CRS classified as laboratory- confirmed CRS (58.95%), clinically confirmed CRS (15.79%), and discarded CRS (25.26%). Clinical manifestations included combination of congenital heart disease and hearing impairment (17.89%), congenital heart disease, ophthalmology abnormalities, and hearing impairment (16.84%), and hearing impairment and ophthalmology abnormalities (13.68%). The data show a high burden of CRS in Surabaya. These implies the urgent need for national rubella immunization program.

Strategies for elimination of rubella in pregnancy and of congenital rubella syndrome in high and upper-middle income countries

Rubella infection generally leads to mild symptoms; otherwise, in pregnant women it can cause severe damages. The only way to prevent rubella is vaccine. Before the introduction of the vaccine, up to 4 babies in 1000 live births were born with CRS.

This work aims to review the most important strategies for the elimination of CRS in upper and high-income countries.

Papers were selected through a PubMed search up to January 2019, using keywords rubella, congenital rubella syndrome and epidemiology. Articles published in the last 12 years and referred to upper income and high-income countries in title or abstract were included.

Sixty-five papers were selected dealing with one or more of the following strategies: increasing of rubella vaccination coverage in childbearing age women, males, immigrants; exploitation of all appropriate occasions; improving of rubella surveillance.

Despite numerous suggestions and indications for valid strategies to eliminate rubella in pregnancy and congenital rubella syndrome, a practical application is often missing.

Diagnosis and medical care for congenital cytomegalovirus infection: An observational study using claims data in Japan, 2010 to 2017

Although early detection and intervention may improve the outcome of the congenital cytomegalovirus (cCMV) infection, few studies assessed the real-world clinical practice for cCMV patients. We analyzed medical claims data to assess the patterns of diagnoses and medical care for cCMV patients.We used a subset of medical claims database (JMDC Claims Database) in Japan, covering 207,547 newborns between April 2010 and March 2017 and observed for at least 6 months. The diagnosis of cCMV and related symptoms and sequelae and medical care, including essential examinations and antiviral treatment, were identified using standardized codes.Overall, we identified 53 (25.5 per 100,000 newborns) cCMV patients diagnosed within 6 months after birth; of these, 83% were diagnosed within 1 month and 68% had at least 1 cCMV-related symptom at birth. Objective hearing tests and fundus examinations were performed within 6 months in 60% and 30% of patients, respectively. Antivirals were prescribed in 26% of patients. During the observation period (median = 33 months), sensorineural hearing loss (49%) and developmental problems (28%) were commonly identified as cCMV-related sequelae. The proportions of the patients continuously followed up with objective hearing tests up to 36 months were 30% in total and 56% in antiviral-treated patients, respectively.The cCMV patients did not necessarily receive a timely diagnosis nor continuous follow-ups in usual clinical practice. Although the universal screening for cCMV may, if implemented, facilitate early diagnosis, it should be accompanied by strategic follow-up plans to support timely interventions.

Phylogeography of rubella virus in Asia: Vaccination and demography shape synchronous outbreaks

Rubella virus causes mild disease in children but for women in the early stages of pregnancy, it can cause spontaneous abortion, congenital rubella syndrome (CRS) and associated birth defects. Despite the availability of an effective vaccine, rubella virus continues to circulate endemically in several regions of the world. This is particularly true in East and Southeast (E/SE) Asia, where control efforts vary widely among countries that are well connected through travel and immigration. It is therefore important to understand how the regional persistence of rubella is affected both by dynamics occurring across countries and susceptibility within countries. Here, we use genetic and epidemiological data from countries in E/SE Asia to explore the phylogeography of rubella virus in this region. Our results underline that metapopulation dynamics are key for rubella persistence and highlight the source-sink population structure of the region. We identify countries that contribute to the regional metapopulation network and link epidemic dynamics to susceptibility profiles within each country. Our results indicate that human movement plays an important role in driving epidemic dynamics in E/SE Asia.

Enhancing Preparedness against Rubella at the Workplace: Proactive Prevention Efforts by the Tokyo Metropolitan Government

In the 2012-2013 rubella epidemic in Japan, most transmissions in Tokyo occurred at workplaces, especially among men aged 20-49 years. This tendency was likely related to previous rubella immunization policies that prioritized female adolescents. Since 2015, the Tokyo Metropolitan Government has been promoting a project to prevent rubella and other infectious diseases in workplaces. Companies participate by choosing one or more of three options: (i) acquire fundamental understanding of infectious diseases, (ii) develop a Business Continuity Plan (BCP) for infectious diseases in the workplace, and (iii) increase rubella antibody prevalence in employees.Criteria for accomplishment are (i) at least 80% of employees complete the infectious disease training modules or (ii) produce a BCP and (iii) at least 90% of employees demonstrate the presence of antibodies at levels sufficient for preventing rubella. As of July 2018, 39.8% (n ＝ 90) of the 226 companies that began participating in 2015-2017 had met at least one accomplishment criteria (Option I, 42.7% of 192 companies; Option II, 19.3% of 140; and Option III, 17.0% of 53). The main project challenges were recruiting companies and following participating companies. Although early in its implementation, this project has made considerable contributions toward rubella elimination in Japan.

Anti-Jo-1 Antibody-positive Interstitial Pneumonia in an Elderly Patient with Congenital Rubella Syndrome

A 71-year-old woman with congenital rubella syndrome (CRS) presented with prolonged cough. No physical findings suggested the presence of any connective tissue diseases. Chest computed tomography showed ground-glass opacities and consolidations in the bilateral lower lobes. She had elevated serum Krebs von den Lungen-6, hypoxemia and positive serum anti-Jo-1 antibody. Bronchoalveolar lavage fluid revealed lymphocytosis with a decreased CD4/CD8 ratio. A transbronchial lung biopsy specimen revealed organizing pneumonia. Based on a diagnosis of interstitial pneumonia with autoimmune features (IPAF), systemic corticosteroids were administered, and a good outcome was obtained. A possible relationship between CRS and IPAF is herein discussed.

Rubella seroprevalence among pregnant women in Beijing, China

Background

Rubella infection in pregnant women can result in serious effects, such as miscarriages, stillbirths, and congenital rubella syndrome (CRS). However, very little is known about the rubella seroprevalence among pregnant women in China.

Methods

This is a cross-sectional and hospital-based study. From June 2016 through March 2017, a total of 324 serum samples from healthy pregnant women were collected in the Shunyi Women and Children’s Hospital of Beijing Children’s Hospital. Rubella-specific IgG antibody was determined by ELISA (Euroimmun, Lübeck, Germany) kits. International assigned cut-off values of ≥10 IU/ml were used to assess the percentage of pregnant women with protective IgG concentrations.

Results

The total rate of protected individuals was 83.3% (95% CI: 78.9%–87.0%). The protective rates of pregnant women in 17–26 years group, 27–36 years group and 37–46 years group were 84.0% (95% CI: 75.3%–90.1%), 81.9% (95% CI: 74.9%–87.4%) and 84.9% (95% CI: 75.8%–90.9%) respectively. No significant difference in protective rates among the three age groups was found (P = 0.83). There were also no statistically significant correlations between protective rates and gravidity (P = 0.84), parity (P = 0.84), birth place (P = 0.16), residence area (P = 0.58), education (P = 0.40) or occupation (P = 0.65).

Conclusions

Despite the generally low vaccination coverage for rubella, most of Chinese pregnant women had potent rubella immunity. However, at least 16.7% of pregnant women were susceptible to rubella, which suggested rubella immunization in Chinese women at or before child-bearing age.

Molecular Epidemiology of Rubella Virus Strains Detected Around the Time of the 2012-2013 Epidemic in Japan

A nationwide rubella epidemic occurred from 2012 to 2013 in Japan, resulting in around 17,000 rubella cases and the birth of 45 infants with congenital rubella syndrome. The aim of this study was to genetically characterize the rubella viruses (RVs) circulating around the time of the epidemic in Japan. In total, 221 RV strains detected from 14 prefectures in Japan between 2010 and 2014 were sequenced in the 739 nucleotide-window region within the E1 gene. The virus strains were chronologically and geographically characterized into groups based on phylogenetic analysis. Among the 221 strains analyzed, 192 (87%), 26 (12%), and 3 (1%) strains were classified into genotypes 2B, 1E, and 1J, respectively. The majority (n = 184) of the genotype 2B strains belonged to lineage 2B-L1 and shared nucleotide homology with the strains detected in Southeast and East Asian countries. Phylogenetic analyses demonstrated that at least six distinct clusters of RV strains (clusters 1-6) induced outbreaks in Japan between 2010 and 2014. Among them, strains from clusters 3, 4, and 6 circulated almost simultaneously during 2012-2013. The cluster 3 strains circulated locally, whereas strains from cluster 4 spread nationwide. The findings suggest that RVs were introduced into Japan many times from neighboring countries. The 2012-2013 epidemic was a complex of outbreaks induced by at least three clusters of RV strains.

Rubella Immune Status in Pregnant Women in a Northern Mexican City

BACKGROUND

The seroepidemiology of rubella virus infection in pregnant women in northern Mexico is largely unknown. We sought to determine the seroprevalence of rubella virus infection in pregnant women in the northern Mexican city of Durango, Mexico. Seroprevalence association with the socio-demographic, clinical and behavioral characteristics of the pregnant women was also investigated.

METHODS

Through a cross-sectional study, we determined the seroprevalence of IgG and IgM anti-rubella virus in 279 pregnant women (mean age 29.17 ± 5.96 years; range 15 - 43 years) attending in a clinic of family medicine using enzyme-linked fluorescent assays. A questionnaire was used to obtain the socio-demographic, clinical and behavioral characteristics of the pregnant women. The association of rubella seropositivity and characteristics of the women was assessed by bivariate and multivariate analyses.

RESULTS

Anti-rubella IgG antibodies (≥ 15 IU/mL) were found in 271 (97.1%) of the 279 pregnant women examined. None of the 279 pregnant women were positive for anti-rubella IgM antibodies. Multivariate analysis of socio-demographic, clinical and behavioral variables showed that seroreactivity to rubella virus was positively associated with national trips (OR = 7.39; 95% CI: 1.41 - 38.78; P = 0.01), and negatively associated with age (OR = 0.26; 95% CI: 0.06 - 0.99; P = 0.04).

CONCLUSIONS

Rate of rubella immunity in pregnant women in the northern Mexican city of Durango is high. However, nearly 3% of pregnant women are susceptible to rubella in our setting. Risk factors associated with rubella seropositivity found in this study may be useful for optimal design of preventive measures against rubella and its sequelae.

Assessing herd immunity against rubella in Japan: a retrospective seroepidemiological analysis of age-dependent transmission dynamics

OBJECTIVE

We aimed to epidemiologically assess rubella herd immunity as a function of time, age and gender in Japan, with reference to the recent 2012-2014 rubella epidemic.

DESIGN

This study is a retrospective seroepidemiological analysis.

MAIN OUTCOME MEASURES

The susceptible fraction of the population was examined as a function of age and time. The age at infection was assessed using reported case data.

RESULTS

Whereas 30 years ago rubella cases were seen only among children, the median (25-75th centiles) age of cases in 2014 was elevated to 32.0 (17.0-42.0) years among males and 27.0 (7.0-37.0) years among females. Susceptible pockets among male birth cohorts 1989-1993 and 1974-1978 were identified, with seropositive proportions of 70.0% and 68.0%, respectively. The majority of female age groups had greater seropositive proportions than the herd immunity threshold, with a minor susceptible pocket for those born from 1989 to 1993 (78.3% seropositive). The age-standardised seronegative proportion decreased to 18.3% (95% CI 16.8% to 19.8%) among males and 15.6% (95% CI 10.0% to 21.2%) among females in 2013, and the immune fraction was not sufficiently below the herd immunity threshold. While the number of live births born to susceptible mothers in 1983 was estimated at 171,876 across Japan, in 2013 it was reduced to 23,698.

CONCLUSIONS

An elevated age at rubella virus infection and the presence of susceptible pockets among adults were observed in Japan. Although, overall, the absolute number of rubella cases has steadily declined in Japan, the elevated age of rubella cases, along with increased numbers of susceptible adults, contributed to the observation of as many as 45 congenital rubella syndrome (CRS) cases, which calls for supplementary vaccination among susceptible adults. Assessing herd immunity is considered essential for routinely monitoring the risk of future rubella epidemics and CRS cases.

Shedding of Rubella Virus among Infants with Congenital Rubella Syndrome Born in Tokyo, Japan, 2013-2014

Rubella is usually a mild illness, with febrile rash being its main symptom. However, serious consequences of rubella infection can result when the infection occurs during the early stages of pregnancy. After the occurrence of a rubella outbreak in Japan that was observed from 2012 to 2013, 45 infants were reportedly born with congenital rubella syndrome (CRS). We prospectively followed the 15 CRS cases reported in Tokyo to determine the virus shedding periods by using nested reverse transcriptase-polymerase chain reaction to detect rubella virus genes. Throast swabs were used for virus detection. The virus shedding period was measured from birth until the time when the sample last tested positive followed by 2 consecutive negative samples. Kaplan-Meier method was used to estimate the proportion of cases remaining positive for rubella virus genes over time. The proportion of CRS cases shedding virus dropped steadily after birth, dropping to 33.8% at 6 months and 16.9% at 12 months. Our findings also suggested that the earlier the mother's onset of rubella during pregnancy, the longer the infant remained positive. Based on our findings, we believe that infants with CRS should be monitored for rubella virus shedding until 1 year of age.

Rubella specific cell-mediated and humoral immunity following vaccination in college students with low antibody titers

OBJECTIVE

This study measured cell-mediated immunity (CMI) and antibodies to clarify the basis of rubella reinfection after vaccination.

METHODS

In a pool of 65 college students, 39 who exhibited hemagglutination-inhibition (HI) antibody titers against rubella of ≤ 1:16 were vaccinated with a rubella vaccine. The CMI was assessed with interferon-gamma release assay.

RESULTS

There was low correlation (r = 0.24) between the antibody titers and interferon-gamma levels at pre-vaccination status. Preexisting interferon-gamma levels were low in some subjects with low HI antibody titers of 1:8 and 1:16. Fifty-seven percent (4/7) of the subjects who were antibody-negative with past history of rubella vaccination at entry onto the study exhibited CMI. And 57% (4/7) of the subjects remained antibody-negative following a second vaccination, despite exhibiting CMI. HI antibody titers increased significantly after vaccination, whereas post-vaccination interferon-gamma levels did not exhibit significant increases. When subjects were divided (based on their past history of vaccination and antibody values) into natural infection and vaccination groups, HI antibody titers (mean ± SD) increased to 1:2(4.4 ± 1.4) from 1: 2(3.2 ± 0.4) (p = 0.065) in the natural infection group and to 1:2(4.4 ± 1.0) from 1:2(3.0 ± 0.8) (p < 0.00001) in the vaccination group following vaccination. The same classification revealed that interferon-gamma values did not increase significantly in either group following vaccination, but the interferon-gamma values at pre- and post-vaccination in the natural infection group were significantly higher than those at pre- and post-vaccination in the vaccination group (p < 0.05 and p < 0.05, respectively).

CONCLUSION

Pre-vaccination interferon-gamma levels in each HI antibody titer group were similar. And there were some subjects with antibody-positive exhibited CMI-negative. These data may explain why rubella reinfection can occur in vaccinated seropositive individuals.