Current status of measles in Japan

Achieving measles elimination and emerging modified measles: Longitudinal measles epidemiology from 1982 to 2021 in Osaka Prefecture, Japan

BACKGROUND

Measles is a contagious viral disease causing infant mortality in developing countries without vaccination programs. In Japan, measles vaccination was launched in 1978, surveillance commenced in 1981, and elimination was achieved in 2015. This was due to improved, legally required surveillance methods and vaccine programs.

METHODS

The data sets of sentinel (1982-2007) and notifiable (2008-2021) disease surveillance, as well as the vaccination coverage, detected genotypes, and seroepidemiology during the study period in Osaka Prefecture, were analyzed. Additionally, the trend under the current notifiable surveillance was compared before (2008-2014) and after (2015-2021) measles elimination.

RESULTS

Under sentinel surveillance, 51,107 cases were reported, predominantly infants aged 1-4 years (63.6 %). Under notifiable disease surveillance, the 781 patients were predominantly in their 20s-30s (43.7 %). From 2000, the age of the major susceptible group increased due to the rise in vaccination coverage, which exceeded 95% for the first dose in 1998 and 90% for the second dose in 2009. Consistent with these data, seroprevalence exceeded 95% in 2011. However, the geometric mean of the antibody titer showed a decreasing trend with a falling number of patients. Compared with before and after measles elimination, the number of modified measles cases increased from 10.1% to 48.2%. During the study period, 398 strains comprising eight genotypes were identified, and the dominant type changed over time. After measles elimination, genotypes B3 and D8, derived from imported cases, became predominant.

CONCLUSIONS

Improved vaccination coverage and surveillance reduced measles cases and increased herd immunity. However, the lack of a booster effect due to the low incidence of measles caused waning antibody titers despite high seroprevalence, which may contribute to the rising rate of vaccine failures causing modified measles. Careful monitoring of measles incidence and herd immunity are necessary for measles eradication.

Vaccine chronicle in Japan

The concept of immunization was started in Japan in 1849 when Jenner's cowpox vaccine seed was introduced, and the current immunization law was stipulated in 1948. There have been two turning points for amendments to the immunization law: the compensation remedy for vaccine-associated adverse events in 1976, and the concept of private vaccination in 1994. In 1992, the regional Court of Tokyo, not the Supreme Court, decided the governmental responsibility on vaccine-associated adverse events, which caused the stagnation of vaccine development. In 2010, many universal vaccines became available as the recommended vaccines, but several vaccines, including mumps, zoster, hepatitis B, and rota vaccines, are still voluntary vaccines, not universal routine applications. In this report, immunization strategies and vaccine development are reviewed for each vaccine item and future vaccine concerns are discussed.

Effect of early measles vaccination (AIK-C strain) for preterm infants

BACKGROUND

The level of maternal antibodies decreases more quickly in preterm than term infants, leaving them unprotected against measles. To protect premature infants from measles, an early vaccination trial was investigated.

METHODS

Changes in the serum measles neutralization test (NT) antibody titer were examined in 152 infants (average gestational period, 29 weeks; average birthweight, 1203 g).

RESULTS

The average antibody titer (2(n)) was 2(3.5) at birth and 2(2.2) at 1-3 months of age, and in all cases, NT antibody titer decreased to <1:4 (150 IU/mL). The AIK-C measles vaccine was given to 17 preterm infants at the age of 6 months, and induced sufficient serological responses without any serious adverse events. NT antibody level did not decay during 12 months after vaccination.

CONCLUSION

Early immunization at 6 months of age is effective to protect preterm infants in the outbreak setting.

No evidence for an association between persistent measles virus infection and otosclerosis among patients with otosclerosis in Japan

Otosclerosis, which is characterized by disordered bone remodeling, occurs exclusively in the human temporal bone. The etiology of the disease is unknown, but a popular hypothesis is that it is caused by persistent measles virus (MV) infection. Paramyxovirus-like filamentous structures were found in otosclerotic lesions of stapes footplates from patients with otosclerosis. Although MV RNAs have been detected in otosclerotic samples by using reverse transcription-PCR, no complete MV mRNA sequence has been reported, nor has infectious virus been isolated from clinical samples. Furthermore, one study failed to obtain evidence of MV infection in otosclerotic bone samples. In this study, we tested, by three different protocols, for the presence of MV in clinical samples from patients with otosclerosis in Japan. We used a highly sensitive reverse transcription-quantitative PCR method which is able to detect viral mRNA in cells infected with MV at around one infectious unit per well. We obtained no evidence of MV infection in bone samples, primary cell cultures derived from stapes bones, or MV-susceptible cell lines (Vero/hSLAM and II-18 cells) cocultured with bone samples or primary cell cultures derived from them. Thus, our results do not support the hypothesis that persistent MV infection is involved in the pathoetiology of otosclerosis.

Evaluating measles surveillance: comparison of sentinel surveillance, mandatory notification, and data from health insurance claims

Inadequate notification is a recognized problem of measles surveillance systems in many countries, and it should be monitored using multiple data sources. We compared data from three different surveillance sources in 2007: (1) the sentinel surveillance system mandated by the Act on Prevention of Infectious Diseases and Medical Care for Patients Suffering Infectious Diseases, (2) the mandatory notification system run by the Aichi prefectural government, and (3) health insurance claims (HICs) submitted to corporate health insurance societies. For each dataset, we examined the number of measles cases by month, within multiple age groups, and in two categories of diagnostic test groups. We found that the sentinel surveillance system underestimated the number of adult measles cases. We also found that HIC data, rather than mandatory notification data, were more likely to come from individuals who had undergone laboratory tests to confirm their measles diagnosis. Thus, HIC data may provide a supplementary and readily available measles surveillance data source.

Molecular evolution of measles viruses circulated in Taiwan 1992-2008

Genetic analyses of viral samples from 74 laboratory confirmed measles cases occurring in Taiwan during 1992-2008 identified six viral genotypes D3, D5, D9, G2, H1 and H2. The most frequently detected genotype, H1, was associated with outbreaks in 1994 and 2002, and was the likely indigenous genotype in 1992. In response to the outbreaks, two catch-up campaigns were launched and a routine second dose of measles, mumps, and rubella vaccine at entry to elementary school was introduced. The vaccination campaigns successfully reduced the number of measles cases in Taiwan, and many of the more recent cases can be traced to importations, primarily from other Asian countries. A number of measles genotypes which were associated with outbreaks in other Asian countries were detected among the more recent cases. The more recent genotype H1 viruses had sequences that were identical to those currently circulating in China or associated with international importation of virus.

Measles viruses of genotype H1 evade recognition by vaccine-induced neutralizing antibodies targeting the linear haemagglutinin noose epitope

The linear haemagglutinin noose epitope (HNE; aa 379–410) is a protective B-cell epitope and considered to be highly conserved in both the vaccine and the wild-type measles virus (MeV) haemagglutinin (H) proteins. Vaccine virus-derived monoclonal antibodies (mAbs) BH6 and BH216, which target the HNE, neutralized MeVs of genotypes B3, C2, D4, D5, D6, D7 and D8, and the vaccine strain Edmonston Zagreb. In the case of genotype H1, only strain Berlin.DEU/44.01 was neutralized by these mAbs, whereas strains Shenyang.CHN/22.99 and Sofia.BGR/19.05 were not. The H gene sequences of these two strains showed an exchange of proline 397 (P397) to leucine (L397). Mutated H proteins, with P397 exchanged to L and vice versa, were compared with original H proteins by indirect fluorescence assay. H proteins exhibiting P397 but not those with L397 were recognized by BH6 and BH216. This indicates that L397 leads to the loss of the neutralizing HNE. In contrast, human sera obtained from vaccinees (n=10) did not discriminate between genotype H1 variants P397 and L397. This concurs with the epidemiological observation that the live-attenuated vaccine protects against both H1 variants. Furthermore, we demonstrated that MeVs of genotype H1 also lack the neutralizing epitopes defined by the vaccine virus-induced mAbs BH15, BH125 and BH47. The loss of several neutralizing epitopes, as shown for H1 viruses currently circulating endemically in Asia, implies that epitope monitoring should be considered to be included in measles surveillance.

Measles resurgence associated with continued circulation of genotype H1 viruses in China, 2005

Measles morbidity and mortality decreased significantly after measles vaccine was introduced into China in 1965. From 1995 to 2004, average annual measles incidence decreased to 5.6 cases per 100,000 population following the establishment of a national two-dose regimen. Molecular characterization of wild-type measles viruses demonstrated that genotype H1 was endemic and widely distributed throughout the country in China during 1995-2004. A total of 124,865 cases and 55 deaths were reported from the National Notifiable Diseases Reporting System (NNDRS) in 2005, which represented a 69.05% increase compared with 2004. Over 16,000 serum samples obtained from 914 measles outbreaks and the measles IgM positive rate was 81%. 213 wild-type measles viruses were isolated from 18 of 31 provinces in China during 2005, and all of the isolates belonged to genotype H1. The ranges of the nucleotide sequence and predicted amino acid sequence homologies of the 213 genotype H1 strains were 93.4%-100% and 90.0%-100%, respectively. H1-associated cases and outbreaks caused the measles resurgence in China in 2005. H1 genotype has the most inner variation within genotype, it could be divided into 2 clusters, and cluster 1 viruses were predominant in China throughout 2005.

Molecular epidemiology of measles virus

Genetic characterization of wild-type measles viruses provides a means to study the transmission pathways of the virus and is an essential component of laboratory-based surveillance. Laboratory-based surveillance for measles and rubella, including genetic characterization of wild-type viruses, is performed throughout the world by the WHO Measles and Rubella Laboratory Network, which serves 166 countries in all WHO regions. In particular, the genetic data can help confirm the sources of virus or suggest a source for unknown-source cases as well as to establish links, or lack thereof, between various cases and outbreaks. Virologic surveillance has helped to document the interruption of transmission of endemic measles in some regions. Thus, molecular characterization of measles viruses has provided a valuable tool for measuring the effectiveness of measles control programs, and virologic surveillance needs to be expanded in all areas of the world and conducted during all phases of measles control.

Measles exportation from Japan to the United States, 1994 to 2006

BACKGROUND

Imported measles cases and outbreaks involving Japanese travelers have been reported from the United States and other countries. For the United States, Japan is the top country of origin. The aims of this study were to analyze measles exportation trends from Japan to the United States and to suggest recommendations for improving monitoring and control in both countries.

METHODS

Reviewing all exportation cases reported to the Centers for Disease Control and Prevention and sentinel measles activity data monitored by the Japanese Ministry of Health between January 1994 and December 2006 (observation period).

RESULTS

A total of 63 cases were reported (median = 4 cases per year). Cases ranged in age from 9 months to 53 years (median = 17 y). Peaks occurred at 13 to 26 years and 12 to 35 months. Six cases were US citizens and 57 Japanese. Ten cases were reported in July and August, followed by eight in February and March. Twenty-seven cases were reported from Hawaii, followed by 15 from California and 6 from New York. Seven cases developed the secondary spread. Three of the cases had previously received one dose of measles vaccine, compared to 35 who were never immunized (25 cases unknown). During the observation period, measles activity exceeded the warning level in 157 weeks, with measles exportation occurring the subsequent week for 30 of these weeks. In comparison, during the 521 weeks in which measles activity was below the warning level, exportation of measles the following week was observed for 21 of those weeks (OR = 5.62, 95% CI = 3.12-10.2, p < 0.001).

CONCLUSIONS

Trend of exported measles cases from Japan to the United States has corresponded with the measles activity trend in Japan. Most of the cases were unvaccinated. This international health problem should be solved by strong leadership of Japanese public health professionals.

Interplay of politics and law to promote health: improving economic equality and health: the case of postwar Japan

The health situation in Japan after World War II was extremely poor. However, in less than 35 years the country's life expectancy was the highest in the world. Japan's continuing health gains are linked to policies established at the end of World War II by the Allied occupation force that established a democratic government. The Confucian principles that existed in Japan long before the occupation but were preempted during the war years were reestablished after the war, facilitating subsequent health improvements. Japan's good health status today is not primarily the result of individual health behaviors or the country's health care system; rather, it is the result of the continuing economic equality that is the legacy of dismantling the prewar hierarchy.

Immune response to measles vaccine in primary school students

This cross sectional study was performed to estimate the prevalence of serological evidence of immunity to Measles in primary school students (age 6-12) that have a history of twice vaccination against measles, on 9 and 15 month old and determining the appropriate age to re-vaccination. Multistage sampling was used to select students to participate in the present study. Immunization status and documentary evidence of immunization was recorded from the Personal Health Record. Measles antibodies were measured using enzyme-linked immunosorbent assay (ELISA). Sufficient blood for antibody testing was obtained from 1665 children, 975 (57%) were girls and 720 (43%) were boys, respectively and mean age was 9.17 +/- 1.53 years. On the whole, 1198 subjects (72%) were seropositive and 467 (28%) were seronegative at all. Among girls and boys, 72 and 71%, were seropositive respectively. These differences were not statistically significant between the two sexes (p = 0.404). Antimeasles antibody titer decreased with increasing age from 6 to 10 years old, (76.5% in 6 years old group vs. 71% in 10 years old group) and then rise to 78% in 11-12 years old group. These differences were not statistically significant between age groups (p = 0.775). the immunity produced by the measles vaccine is not enough. Decrease of protective effect of measles vaccine, suggests the necessary of preschool revaccination.

Development of a new neutralization test for measles virus

Sero-epidemiological studies are required to identify populations susceptible to measles. The hemagglutination inhibition (HI) test is no longer sensitive enough to confirm immunity to measles, and at present the particle agglutination (PA) test and enzyme-linked immunosorbent assay (EIA) are employed. The most reliable method is the neutralization test (NT), but it is time-consuming and requires experience. To simplify the NT, a recombinant measles AIK-C virus expressing green fluorescence protein (GFP-MVAIK) was constructed and used as a challenge virus. Plaques and cytopathic effects were visualized under ultraviolet light and detected easily, and measuring the intensity of the fluorescence enabled a reduction in the time-consuming steps. Neutralizing antibody titers of a complete inhibition neutralization test were equivalent to those of a 90% plaque reduction neutralization test. Comparison of four methods, HI, PA, EIA and the complete inhibition neutralization test, showed that only the results of EIA correlated well with those of the complete inhibition neutralization test, but sera with borderline levels by EIA were sometimes negative by the complete inhibition neutralization assay.

Promoting measles vaccination in attendees not yet immunized at day-care centers in Kyoto City

BACKGROUND

Due to the low measles vaccination rate, localized measles epidemics occasionally occur in Japan with the majority of sufferers being children under 2 years of age. Despite an increased risk of infection at day-care centers, the measles vaccination coverage for day-care attendees is lower than children who are reared-at-home or attend kindergartens. This study aims to describe the current state of measles prevention policy at day-care centers and to examine factors associated with vaccine promotion.

METHODS

A cross-sectional study using anonymous self-administered questionnaires were distributed to the director or person-in-charge at 250 all licensed day-care centers in Kyoto City, Japan, in 2004. The preventive measures against measles at day-care centers and factors related to carrying out the promotion of measles vaccination were examined. Descriptive statistics and odds ratios (OR) using a logistical model were presented.

RESULTS

Out of 250 day-care centers, 187 questionnaires were returned (response rate, 74.8%). Measles vaccination history was taken at 161 day-care centers (86.1%) at the time of enrollment; only 61 day-care centers (32.6%) took a history during the school year. A total of 101 day-care centers (54.0%) promoted measles vaccination in day-care attendees who had not yet been immunized. Day-care centers which promoted it were more likely to be 'public facility' (OR, 3.09) and 'having opportunities to learn about vaccination' (OR, 5.55). After adjustment, 'having opportunities to learn about vaccination' and 'having knowledge that measles vaccination is best under the age of 15 months' were significantly related to carrying out the promotion of measles vaccination (OR, 6.47; 95% confidence interval, 2.52-18.61; OR, 3.12; 95% confidence interval, 1.45-6.95, respectively).

CONCLUSION

Preventive measures for measles at day-care centers are currently insufficient. Increasing opportunities to learn about vaccination may encourage promotional behavior.

Isolation of measles virus from middle ear fluid of infants with acute otitis media

Measles virus was isolated from the middle ear fluid (MEF) of two infant cases of acute otitis media (AOM) associated with measles. This is the first report on the isolation of measles virus from the MEF in patients with AOM, and possibility of the measles virus as a causative agent of AOM was suggested.

Review of the temporal and geographical distribution of measles virus genotypes in the prevaccine and postvaccine eras

Molecular epidemiological investigation of measles outbreaks can document the interruption of endemic measles transmission and is useful for establishing and clarifying epidemiological links between cases in geographically distinct clusters. To determine the distribution of measles virus genotypes in the prevaccine and postvaccine eras, a literature search of biomedical databases, measles surveillance websites and other electronic sources was conducted for English language reports of measles outbreaks or genetic characterization of measles virus isolates. Genotype assignments based on classification systems other than the currently accepted WHO nomenclature were reassigned using the current criteria. This review gives a comprehensive overview of the distribution of MV genotypes in the prevaccine and postvaccine eras and describes the geographically diverse distribution of some measles virus genotypes and the localized distributions of other genotypes.

A simple method for the detection of measles virus genome by loop-mediated isothermal amplification (LAMP)

Approximately 20,000-30,000 measles patients were reported in a surveillance of infectious diseases because of low vaccine coverage of 80% in Japan. Among them, some were thought to be secondary vaccine failure (SVF) with generally mild or non-typical measles illness and sometimes became a source of further transmission. We have developed a new, sensitive, and rapid method to detect the measles virus genome by reverse transcription loop-mediated isothermal amplification (RT-LAMP). We examined 50 nasopharyngeal secretion (NPS) samples that were obtained during the 1999 outbreak and stored at -70 degrees C and fresh NPS, lymphocytes and sera from 11 patients in 2003. Total RNA was extracted from the samples and subjected to reverse transcription-polymerase chain reaction (RT-PCR) and RT-LAMP. We detected the genomic RNA corresponding to at least 0.01-0.04 TCID50, 30-100 copies in samples by RT-LAMP within 60 min after extraction of RNA, and all four genotypes isolated in Japan were equally amplified. Specific DNA amplification was monitored spectrophotometrically by real time turbidimeter and the quantity of RNA was calculated. Measles virus genome was detected in 44 of 50 stored NPS by RT-PCR and in 49 by RT-LAMP. The vaccine strain was discriminated from wild strains after sequencing the LAMP products. RT-LAMP is a useful rapid diagnostic method for the detection of measles virus without any special apparatus, showing higher sensitivity than RT-PCR, and expected to be applied for hospital-based infection control and for laboratory-based measles surveillance.

Measles vaccine coverage and factors related to uncompleted vaccination among 18-month-old and 36-month-old children in Kyoto, Japan

BACKGROUND

Due to low vaccine coverage, Japan has not only experienced outbreaks of measles but has also been exporting it overseas. This study aims to survey measles vaccine coverage and the factors uncompleted vaccination among community-living children.

METHODS

Subjects were the parents whose children had undergone either an 18-month or a 36-month checkup publicly provided by Kyoto City during November 2001 to January 2002. An anonymous self-administered questionnaire survey was conducted.

RESULTS

The coverage was 73.2% among the 18-month-old children (n = 2707) and 88.9% among the 36-month-old children (n = 2340), respectively. The following characteristics of mothers were related to uncompleted measles vaccination: aged below 30, working, concerned about the adverse events of the vaccine, and had insufficient knowledge. Similarly, the following characteristics among children were related to uncompleted measles vaccination: not the first-born child, interacting with other children in group settings. The coverage was the lowest among the children whose mothers were concerned about the adverse events of the vaccine without proper knowledge of measles and its vaccination.

CONCLUSION

To increase vaccine coverage among children, parents' awareness about measles and vaccination against it should be promoted, especially for working mothers. Efforts to enhance access to vaccination services and to communicate with parents about changing vaccination schedules are necessary.

Measles virus genotype circulation in Spain after implementation of the national measles elimination plan 2001-2003

Molecular characterization of measles virus is important for disease surveillance and for monitoring elimination of the virus throughout the world. Furthermore, knowledge of genotype distribution in as many countries as possible, is useful for tracing the origin of a strain, especially in countries without endemic measles disease, where most cases are imported. Data on genotypes circulating in Spain from 1970 to 1997 showed the prevalence of genotypes C1, C2, and D6, with subsequent replacement of each other. After the establishment of the Spanish Measles Elimination Plan, genotyping with a new retrotranscriptase polymerase chain reaction (RT-PCR) was undertaken directly on 92 specimens, corresponding to 90 patients, which were positive for measles by a different diagnostic RT-PCR. Genotypes B3, D4, D8, A, C2, H1, and D7 were found in different autonomous communities (Madrid, Balearic Islands, Valencia Community, Extremadura, Andalusia, Canary Islands and Murcia) between 2001 and 2003 with none of these genotypes being prevalent. After the introduction of the vaccine in 1978, the incidence of the disease decreased from 150,000 cases in 1977 to 64 in 2002. This could be the reason for the change observed in the pattern of measles genotype circulation, since this pattern was reported in countries at an advanced stage of eradication of measles. This report considers that Spain is on the way to eradicating measles.

Prevalence of measles, rubella, mumps, and varicella antibodies among healthcare workers in Japan

OBJECTIVES

To evaluate the immune status of healthcare workers (HCWs) against measles, rubella, mumps, and varicella in Japan, and to promote an adequate vaccination program among HCWs.

SETTING

University of Tokyo Hospital.

PARTICIPANTS

Eight hundred seventy-seven HCWs.

DESIGN

Serologic screening for measles, rubella, mumps, and varicella was performed on HCWs. Antibodies against measles, rubella, and mumps were detected using hemagglutination inhibition (HI) assay ($4.20 per test). If serum was negative by HI assay, enzyme-linked immunosorbent assay (EIA) was performed ($12.60 per test). Anti-varicella antibodies were detected by EIA only.

RESULTS

Among tested HCWs, 98.5%, 90.4%, 85.8%, and 97.2% had immunity to measles, rubella, mumps, and varicella, respectively. All those born before 1970 were seropositive for measles. However, individuals susceptible to rubella, mumps, and varicella were present in all age groups. The sensitivities and negative predictive values of HI assay compared with EIA were 86.6% and 11.3% for measles, 99.1% and 92.2% for rubella, and 47.8% and 24.1% for mumps, respectively. For measles and mumps, prevaccination screening by HI assay in combination with EIA led to significant savings compared with EIA only. In contrast, it was estimated that prevaccination screening using only HI assay would be more economical for rubella.

CONCLUSIONS

Aggressive screening and vaccination of susceptible HCWs was essential regardless of age. Prevaccination serologic screening using a combination of HI assay and EIA was more economical for measles and mumps.

Measles vaccines and the potential for worldwide eradication of measles

The annual number of reported measles cases in the United States has declined from between 3 million and 4 million in the prevaccine era to <100 cases in association with the highest recorded immunization rates in history. Because of continued importation of measles into the United States, young children who are not vaccinated appropriately may experience more than a 60-fold increase in risk of disease. Unsubstantiated claims suggesting an association between measles vaccine and neurologic disorders have led to reduced vaccine use and a resurgence of measles in countries where immunization rates have declined below the level needed to maintain herd immunity. To address the possibility of worldwide control of measles, efforts to ensure high immunization rates among people in both developed and developing countries must be sustained.

Molecular epidemiology of measles virus in Japan

BACKGROUND

Measles virus has been classified into 22 genotypes. The present report examines the molecular epidemiology of measles virus in Japan from 1984 to 2002, and the epidemiological link between imported cases in several foreign countries and Japanese strains was elucidated from the literature.

METHODS

B95a or Vero cells was used to isolate the measles virus. The measles virus genome was amplified in the N and H genes by reverse transcriptase-polymerase chain reaction and were partially sequenced. Phylogenetic analysis of a partial sequence of the N gene, from position 1230 to 1685, of the recent measles strains was performed in comparison with the World Health Organization reference strains.

RESULTS

There were large outbreaks of measles in Japan in 1984, 1987-1988, 1991-1993, and 2001-2002 and each outbreak was caused by a different genotype. Genotype C1 was an indigenous strain for a long period before 1985, while D3 was isolated in 1987-1988 and D5 in 1991-1993 outbreaks. In addition, the Chicago-type D3 caused sporadic regional outbreaks from 1998 to 1999. After 2000, H1 became the dominant circulating strain. It should be noted that the Japanese strains were detected as imported cases by epidemiological linkage in several countries.

CONCLUSIONS

Among the recent circulating strain of measles virus in Japan the genotype H1 was dominant after 2000 and the Japanese strains D3, D5, and H1 were exported to several countries. It is recommended that Japan should adopt a more extensive and active vaccination strategy for measles elimination in line with other countries in the world.

Placental transfer of measles antibodies: effect of gestational age and maternal vaccination status

Despite nationwide measles vaccination coverage in Israel of over 90%, repeated outbreaks of measles have spread from isolated communities with poor immunization uptake. Some severely affected individuals were children under 1 year of age, including premature infants. We evaluated the serological status of 195 newborn infants and their 161 mothers divided into four groups: vaccinated mothers (VMs) and premature infants, VM and full term infants, naturally immunized mothers (NIMs) and premature infants, NIM and full term infants. Maternal and cord blood measles antibody titers were determined by haemagglutination inhibition (HI) test and microneutralization test (mNT). Fewer than 40% of preterm infants of VM and less then 70% of preterm infants of NIM had protective titers at birth. The results of this study may aid in formulating new measles vaccination recommendations for preterm infants.