Low measles seropositivity rate among children and young adults: a sero-epidemiological study in southern China in 2008

One single-center serological survey on measles, rubella and mumps antibody levels of people in Youyang, China

Although measles, rubella and mumps elimination had achieved great progress in recent years, outbreaks were still reported worldwide. Serological surveillance on the remaining susceptibility in the population is essential to evaluate the preventive policy, estimate the current risk of infection, and predict evolutions in the future. In this study, we aimed to investigate the prevalence of seropositivity of antibodies against measles, rubella and mumps in a population of all ages in Youyang, southwest China. A cross-sectional hospital-based study was conducted among 657 cases who attended to Youyang Hospital from Sep 2018 to Aug 2019. Sero IgG antibodies were measured by ELISA. No difference in the seropositivity of antibodies against measles, rubella and mumps was found between neither urban vs. rural, nor male vs. female. The overall seropositivity of anti-measles, rubella, mumps IgG antibodies was 81.1% (95% CI: 78.0-83.9), 65.9% (95% CI: 62.2-69.4) and 63.2% (95% CI: 59.4-66.8), respectively. The IgG seropositivity varied with age significantly. In this study, the seropositivity of antibodies against measles, rubella and mumps among the participants was insufficient in the population, especially among infants, teenagers and productive women, who were suggested to booster the immunity. To better control and eliminate measles, mumps and rubella-related diseases, nation-wide active laboratory-supported surveillance, outbreak investigation and revaccination for vulnerable population are needed.

Risk of Absence of Measles Antibody in Healthcare Personnel and Efficacy of Booster Vaccination

We aimed to identify the presence of the measles IgG antibody (mIgG-Ab) in healthcare personnel and finding out who needs the measles vaccination. The history of measles vaccination was obtained from the national vaccine registry. A baseline mIgG-Ab test was performed, and the measles vaccine was administered to participants who tested negative or equivocal for mIgG-Abs. During the study, 2885 (87.3%) of the 3303 employees were tested for measles serostatus. The baseline seropositivity rate for mIgG-Abs was 91.9%. Among the 234 seronegative cases, 82.9% were born after 1985. The seroprevalence rate was lower in those who received the measles–mumps–rubella (MMR) vaccine >10 years before the testing time, especially if they were born after 1985 and if there was only one previous record of vaccination. Among the 234 seronegative cases, MMR vaccination was administered in 174 cases, of which serostatus was evaluated in 146 cases. After the first dose, positive seroconversion was achieved in 126 participants (86.3%). After a second dose, 15 achieved (75.0%) positive seroconversion. In healthcare personnel born after the period when measles incidence significantly decreased, it may be necessary to reassess their immune status for measles if more than 10 years have elapsed since the last vaccination.

Measles Outbreak in a Rural Population in Bahar District, Hamadan Province, West of Iran in 2018

Background: Measles is in elimination phase in Iran. Following occurrence of two cases of measles in two children under six years old with the history of measles immunization in one of the villages affiliated to Bahar District, west of Hamadan Province, northwest of Iran, this study was conducted to determine the immunity status of people living in the village affected by the measles outbreak in spring of 2018.

Study design: A cross-sectional (descriptive-analytical) study.

Methods: Overall, 272 populations of 0-40 yr old in the village affected by outbreak were enrolled. Multistage sampling was used for choosing participants. The data collection tool was a researcher-made checklist used to collect epidemiological data including demographic characteristics and vaccination status. Blood samples were taken from them and sent to the measles reference laboratory for IgG testing. The amount of optical density (OD) greater than 0.2 was considered as positive and less than 0.1 negative, respectively.

Results: The mean age of the study population was 17.4 ±11.8 yr and the sex ratio was almost the same. Levels of antibodies against measles were positive in 63.24%, intermediate in 12.5% and negative in 24.26%. There was no significant difference between the immunity status of the subjects with gender (P=0.236) and age group (P=0.113). Pearson correlation results showed that in males there was a significant positive correlation between the age of the participants and the serum IgG level (r = 0.26, P=0.003).

Conclusion: Measles immunity in communities is not sufficient to prevent outbreaks and small epidemics, and it is recommended that periodically, serological assessments carried out at community level and especially at high-risk groups.

Measles immunity in the China-Myanmar border region, Lincang city, Yunnan province, 2017

Background: A recent measles importation-related outbreak in the China-Myanmar border region required outbreak response immunization to stop the outbreak, raising the question of measles immunity in the area. We conducted two measles serological surveys to develop a seroepidemiological profile of native Chinese citizens and registered Myanmar immigrants to identify strategies to promote measles elimination in the border region.Methods: We conducted a clinic-based measles serosurvey of Myanmar registered immigrants (n = 300) and a population-based serosurvey of Chinese Lincang residents (n = 355). Serum samples were tested with enzyme-linked immunosorbent assays to assess immunity to measles.Results: We found that Myanmar immigrants had a seropositivity rate of 85.3% (95% CI: 81.3-89.4) with a GMT of 924.9 mIU/ml, and Lincang Chinese nationals had a seropositivity rate of 94.6% (95% CI:92.3-97.0) with a GMT of 1363.3 mIU/ml. Myanmar children 2-6 years of age and 7-14 years of age were more likely to be susceptible to measles than same-aged Chinese children: odds ratios 23.00 (95% CI: 5.10-103.69, P < .001) and 7.95 (95% CI: 1.66-38.01,P = .009), respectively.Conclusions: We recommend conducting a catch-up vaccination program for Myanmar children ≤15 years old.

Were infections in migrants associated with the resurgence of measles epidemic during 2013-2014 in southern China? A retrospective data analysis

OBJECTIVE

The 2009 province-wide and 2010 nationwide supplementary immunization activities (SIAs) greatly reduced measles prevalence in Guangdong, a province in southern China with the largest migrant population. However, during 2013-2014, Guangdong experienced a resurgence of the measles epidemic. This study was performed to examine the association between infections in migrants and the resurgence of the measles epidemic.

METHODS

The records of 22 362 clinically and laboratory-confirmed measles cases from the years 2009 to 2014 were extracted from the National Infectious Disease Monitoring Information System. The epidemiological characteristics of infections in migrants during 2009-2012 were compared to those during 2013-2014.

RESULTS

Infections in migrants were not significantly associated with the resurgence of the measles epidemic in 2013-2014 (p=0.98). Nevertheless, for infections among locals and migrants during 2009-2012 and 2013-2014, substantial increases in the proportion of infection were detected among children aged <8 months and the unvaccinated population (p<0.01).

CONCLUSIONS

The study findings suggest that infections in migrants might not have been the major cause of the epidemic resurgence of measles. Instead, the resurgence was likely due to infections among children aged <8 months and the unvaccinated. Thus, officials are advised to give higher priority to appropriate populations when formulating control measures, and to strengthen routine surveillance of vaccination coverage among them.

Genome-wide association study of an unusual dolphin mortality event reveals candidate genes for susceptibility and resistance to cetacean morbillivirus

Infectious diseases are significant demographic and evolutionary drivers of populations, but studies about the genetic basis of disease resistance and susceptibility are scarce in wildlife populations. Cetacean morbillivirus (CeMV) is a highly contagious disease that is increasing in both geographic distribution and incidence, causing unusual mortality events (UME) and killing tens of thousands of individuals across multiple cetacean species worldwide since the late 1980s. The largest CeMV outbreak in the Southern Hemisphere reported to date occurred in Australia in 2013, where it was a major factor in a UME, killing mainly young Indo-Pacific bottlenose dolphins (Tursiops aduncus). Using cases (nonsurvivors) and controls (putative survivors) from the most affected population, we carried out a genome-wide association study to identify candidate genes for resistance and susceptibility to CeMV. The genomic data set consisted of 278,147,988 sequence reads and 35,493 high-quality SNPs genotyped across 38 individuals. Association analyses found highly significant differences in allele and genotype frequencies among cases and controls at 65 SNPs, and Random Forests conservatively identified eight as candidates. Annotation of these SNPs identified five candidate genes (MAPK8, FBXW11, INADL, ANK3 and ACOX3) with functions associated with stress, pain and immune responses. Our findings provide the first insights into the genetic basis of host defence to this highly contagious disease, enabling the development of an applied evolutionary framework to monitor CeMV resistance across cetacean species. Biomarkers could now be established to assess potential risk factors associated with these genes in other CeMV-affected cetacean populations and species. These results could also possibly aid in the advancement of vaccines against morbilliviruses.

Measles Antibodies in Mother-Infant Dyads in Tianjin, China

Background

Many measles cases in Tianjin, China, occur in infants whose mothers were born after widespread vaccination programs. We assessed age-specific decreases in maternal measles antibodies in infants and examined maternal and infant characteristics in relation to infant antibody titers.

Methods

Infant and mother dyads were enrolled from a sample of immunization clinics in all Tianjin districts. Participants' antibody titers were measured from dried blood spots. A multivariable log-linear model regressed infant antibody titers onto infant and mother characteristics.

Results

Among 551 infants aged ≤8 months, protective levels of measles antibodies were observed in infants whose mothers had measles titers ≥800 IU/mL (mean antibody titer, 542.5 IU/mL) or 400 to <800 IU/mL (mean, 202.2 IU/mL). Compared with infants whose mothers had no history of disease or vaccination, those with a history of disease had 1.60 times higher titers (95% confidence interval, 1.06-2.43).

Conclusions

Limited vaccination programs in the 1980s have resulted in many Chinese women with inadequate protection against measles and an accordingly low efficiency of transplacental transmission to a fetus. Current vaccination programs, which target children aged 8 months through adolescence may be ineffective in controlling transmission of measles to infants.

Identify the susceptibility profile to measles in the general population: Serological survey of measles antibodies in Shaanxi province, China, in 2016

The reported coverage with two doses of the measles vaccine (MCV) in Shaanxi Province, China, is greater than 95%, but the measles incidence over the whole province remains high. Cross-sectional serological surveys of measles antibodies in Shaanxi Province were conducted in 2016 to assess the population's immunity. The measles IgG levels were measured in serum samples using ELISA. The geometric means concentration (GMC) levels and seroprevalence rates with 95% CIs were calculated by region, gender, and age. A total of 3574 serum samples were collected from participants aged from 2 months to 49 years. The GMC of measles antibodies was 471.3 mIU/ml (95% CI: 445.9-498.2 mIU/ml), and the seroprevalence was only 85.9% (95% CI: 84.8-87.1%). A significant difference in the GMC (P < .05) but not the seroprevalence (P > .05) was observed among the 3 regions. The report measles incidences were high in individuals aged 0-7 months (33.2/100 000) and 8-17 months (26.8/100 000). Although both measles immunity (90.7%) and MCV coverage (89.7%) were low in children aged 8-17 months, the measles seroprevalence in adults was high at greater than 90%. These results revealed that further actions may be taken to increase vaccination coverage in children aged 8 months to 5 years over the whole province and teenagers in the south region. In particular, timely administration of the first MCV dose should be emphasized to prevent measles epidemics in children aged 8-17 months. Vaccination strategies may be varied by age and region.

Pre-vaccination evolution of antibodies among infants 0, 3 and 6months of age: A longitudinal analysis of measles, enterovirus 71 and coxsackievirus 16

BACKGROUND

Due to waning levels of maternal antibodies (measles; enterovirus 71, EV71; and coxsackievirus A16, CoxA16), some infants may lose protection against infection prior to vaccination. Using a longitudinal design, we examine how maternal antibody levels evolve over time in infants prior to vaccination.

METHODS

In 2013-2014, we collected sera at ages 0, 3 and 6months from infants. We assayed for levels of measles IgG antibody (717, 233 and 75 sample sera tested at months 0, 3 and 6, respectively), and neutralizing antibodies for EV71 and CoxA16 (225, 217, and 72). Demographic and health information were collected, and a linear mixed model (LMM) was used to describe antibody levels over time.

RESULTS

Pre-vaccination monotonic antibody decreases were observed for measles (1410, 195 and 22mIU/ml, p<0.001), EV71 (1:19.9, 6.3 and 4.5, p<0.001) and CoxA16 (1:16.3, 5.9, and 4.5, p<0.001). At 6months of age, only 2.7% (95%CI, 0.6-8.3), 6.8% (95%CI, 2.7-14.4) and 5.6% (95%CI, 1.9-12.7) of infants were antibody positive for measles, EV71 and CoxA16, respectively. LMM findings indicated that infants with higher antibody titers at birth experienced a greater loss of antibody level. An infection rate of 1.3% (95%CI, 0.1-6.1) was reported for both EV71 and CoxA16.

CONCLUSIONS

Further modifications of vaccination strategies for measles, earlier vaccination for EV71 infection, and deployment of a CoxA16 vaccine need to be considered to limit infection among the very young.

Seroprevalence of Measles Antibodies and Predictors for Seropositivity among Chinese Children

Background: Supplementary measles immunization has been implemented since 2010 throughout China, yet few studies have reported its effect in the northwest regions. Methods: A cross-sectional study was conducted among children aged 2 to 4 years old (n = 755) from February to September 2014 in 25 towns of Qian County, Shaanxi Province. Blood samples were analyzed for measles antibodies using enzyme-linked immunosorbent immunoglobulin G (IgG) assays. Socio-demographic factors were assessed by questionnaire. Data on vaccine dose were collected from town medical records. Univariate and logistic regression analyses were used to determine factors associated with measles antibody seropositivity. Results: Measles antibody seroprevalence was 91.13% (95% CI: 89.52-92.83) in our sample. Compared with children whose mother's highest education was primary school, seroprevalence was higher in children whose maternal education was middle school (adjusted OR: 1.4, 95% CI: 0.7-2.8), high school (adjusted OR: 2.4, 95% CI: 1.3-7.7), and college/university (adjusted OR: 2.9, 95% CI: 1.2-9.3). Vaccine dose was positively associated with seropositivity. Conclusions: Measles seroprevalence is high in China and is associated with the mother's education and vaccine dose.

Measles epidemics and seroepidemiology of population in Wujin, Changzhou city, Jiangsu province, China 2015

The measles epidemic was rather severe in Wujin 2015, and a seroprevalence survey of measles antibody was conducted during June to September 2015 in Wjin district of Changzhou city. Blood samples were collected from community health population and convenient samples of residual blood from hospitals. Measles-specific IgG levels were measured by ELISA assay. A total of 122 measles cases were reported 2015 in Wujin district with an incidence of 8.31 per 100000 populations. A large proportion of measles cases were adults ≥20years (62.30%) and infants aged <18months (28.69%). Floating population accounted for 68.57% of all cases. 1070 blood samples aged from 9months to 49years old were collected and the overall seroprevalence and geometric mean titer (GMT) of measles were 82.71% and 551.19mIU/ml, respectively. Although the seroprevalence among children aged 9months to 4years was consistently over 90%, it began to decrease since 24months, and till the age of ≥10years, the seroprevalences were all <80%, however, the seroprevalence rised to above 80% in people over 40years. There were no significant differences between the two blood sample sources in the level of seroprevalence and GMT. Also no significant differences were observed in the seroprevalence of measles and GMT levels between genders. The seroprevalence and GMT in people with measles vaccination were higher than those without measles vaccination or people whose measles vaccination are unknown (P<0.001). Our study indicated that the adult measles cases have become a serious problem in Wujin district, which may mainly relate to the increasing size of the floating population with low measles vaccine coverage. The seroprevalence of measles decreased dramatically with increasing age since teenagers, which may mainly caused by waning vaccine-induced immunity. Therefore, it is necessary to strengthen measles vaccine in these people especially floating population.

Association between seroprevalence of measles and various social determinants in the year following a measles outbreak in Turkey

OBJECTIVES

Despite an ongoing measles elimination programme, a measles outbreak occurred in 2013 in Turkey. Population-based seroprevalence studies are needed to determine seronegativity and explore the reasons for this outbreak. This study aimed to explore the seroprevalence of measles and its association with various social determinants in a provincial population in Turkey in the year following a measles outbreak.

STUDY DESIGN

Cross-sectional study.

METHODS

This study was conducted in Manisa Province in 2014 in a sample of 1740 people aged >2 years. The dependent variable was the seroprevalence of measles. Independent variables were sex, age, migration, household size, household density, income, education level, existence of chronic disease and occupational class. Blood samples were collected from participants at family health centres. The presence of specific measles antibodies in serum samples was determined using an anti-measles virus IgG enzyme-linked immunosorbent assay test. Chi-squared test and logistic regression analysis were performed.

RESULTS

Overall, data from 1250 people were analysed. The seroprevalence of measles in the whole study population was 82.2% (95% confidence interval 80.0-84.2). Seroprevalence was 55.4% among subjects aged 2-9 years, 48.7% among subjects aged 10-19 years, 74.1% among subjects aged 20-29 years and 93.6% among subjects aged 30-39 years (P < 0.01). Seroprevalence in subjects aged >40 years was >95%. The lowest seroprevalence was found in primary school children (40.2%), followed by those below the age for primary education (69.8%) and secondary school graduates (75.1%). The prevalence of measles seronegativity was not associated with any of the social determinants when adjusted for age.

CONCLUSIONS

The seroprevalence of measles was lower than expected in the study population and was particularly low in subjects aged <30 years of age despite previous vaccination. Seroprevalence was not associated with social determinants of health that confirmed either an even distribution of virus exposure or fair access to vaccination services. However, the current seroprevalence cannot be sufficiently effective to reach the measles elimination targets, suggesting that it may be necessary to re-evaluate the need for an extra dose of measles vaccine.

Placental antibody transfer efficiency and maternal levels: specific for measles, coxsackievirus A16, enterovirus 71, poliomyelitis I-III and HIV-1 antibodies

Maternal antibodies transported across the placenta can provide vital immunity against infectious pathogens for infants. We here examine maternal antibody (MA) levels and their association with neonatal antibody levels. Pregnant women of gestational age ≥35 weeks were enrolled at a Guangzhou China hospital and mother-infant paired sera were collected. Measles IgG antibody was detected using ELISA assay, neutralizing antibodies titers against coxsackievirus A16 (CA16), enterovirus 71 (EV71), PV I-III and HIV-1 were performed. 711 mother-infant pairs were enrolled and positive relationships for paired serums were found (r: 0.683-0.918). 81.6%, 87.0%, and 82.3% of mothers, and 87.3%, 72.7%, and 72.2% of newborns were positive for measles, CA16 and EV71 antibodies respectively. The highest Neonatal: maternal ratio (NMR) was found in measles (1.042) and the ratios for the other pathogens ranged from 0.84 to 1.00. Linear regressions showed that log(NMR) decreased by a factor of 0.04-15.43 as log(MA) levels increased. A second analysis restricted to maternal positive measles sera revealed that MA measles of was still inversely associated with NMR. Low NMR was found in high MA HIV + serums among 22 paired sera. MA levels appear to play a role determining transplacental antibody transfer; further study is needed to reveal the mechanism.

Seroepidemiology for measles among elementary school children in Northern Taiwan

BACKGROUND

Despite the high vaccination coverage in Taiwan, sporadic cases or small cluster of measles still occur every year. Nevertheless, few studies provided information about the serostatus for measles in recent years. This cross-sectional survey aimed to establish the seroepidemiologic data of measles among elementary school children in New Taipei City, Taiwan during 2012-2013.

METHODS

A multistage stratified sampling design using 14 variables was employed to obtain samples. All selected schoolchildren were bled for the serologic tests of measles by both chemiluminescence immunoassay (CLIA) and enzyme immunoassay (EIA).

RESULTS

A total of 856 schoolchildren from 14 schools were recruited in this study. Among these individuals, the overall seropositive rates for measles were 82.24% and 92.17% by the Liaison and NovaLisa assays, respectively. For schoolchildren in each grade, the seropositive rates were > 90% for Grade 1, and then decreased gradually to 70-80% for Grade 6 (p < 0.001 for both methods). A decay of measles-specific immunoglobulin G titers was also observed with the maximum drop between Grade 1 and Grade 2 (declining trend of p < 0.001 for both).

CONCLUSION

Although the seropositive rate of measles was > 90% for Grade 1, the rate for Grade 6 was only in the range of 70-80%, which may be a challenge to prevent outbreaks of measles in the future and should be monitored meticulously.

Systematic Review of Measles and Rubella Serology Studies

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

A 16-year review of seroprevalence studies on measles and rubella

The determination of the seroprevalence of vaccine-preventable diseases is critical in monitoring the efficacy of vaccination programmes and to assess the gaps in population immunity but requires extensive organisation and is time and resource intensive. The results of the studies are frequently reported in peer-reviewed scientific, government and non-government publications. A review of scientific literature was undertaken to advise the development of WHO guidelines for the assessment of measles and rubella seroprevalence. A search of the National Library of Medicine's PubMed online publications using key words of 'measles', 'rubella', combined with 'serosurvey', 'seroprevalence', 'immunity' and 'population immunity' was conducted. A total of 97 articles published between January 1998 and June 2014 were retrieved, 68 describing serosurveys for measles and 58 serosurveys for rubella, conducted in 37 and 36 different countries respectively. Only 13 (19%) and 8 (14%) respectively were UN classified "least developed countries". The study sample varied markedly and included combinations of male and female infants, children, adolescents and adults. The study sizes also varied with 28% and 33% of measles and rubella studies respectively, having greater than 2000 participants. Microtitre plate enzyme immunoassays were used in 52 (76%) measles studies and 40 (69%) rubella studies. A total of 39 (57%) measles and 44 (76%) rubella studies reported quantitative test results. Seroprevalence ranged from 60.8% to 95.9% for measles and 53.0% to 99.3% for rubella studies. The review highlighted that infants lost maternally-acquired immunity within 9months of birth and were unprotected until vaccination. Two groups at higher risk of infection were identified: young adults between the ages of 15 and 30years and immigrants.

Epidemiological investigation of Measles in Bozhou City, China, from 2005 to 2015

BACKGROUND

Measles is one of the most highly contagious diseases which have not been eliminated in China. This study aimed to investigate the epidemiological characteristics of measles in Bozhou city, China between 2005 and 2015 and provide scientific basis for the prevention, control and elimination of measles.

METHODS

Cases of measles derived from the China Information System for Disease Prevention and Control, and demographic data were obtained from the Public Security Bureau of Bozhou city.

RESULTS

Among the 2934 cases, the average annual incidence of measles was 45.934 (per 1,000,000 persons) and no death occurred. The incidence of males was higher than females (Z = 10.794, p < 0.05). Scattered children accounted for 63.2% (1854/2934) in occupation distributing. In terms of immunization history of cases, 57.5% had 0 doses, 15.0% had one dose, 7.5% had two doses and others were uncertain.

CONCLUSIONS

Our study has investigated the epidemiological characteristics of measles in Bozhou City. To eventually eliminate measles in Bozhou city, improving measles vaccination coverage and quality of routine immunization services were important.

A population profile of measles susceptibility in Tianjin, China

BACKGROUND

Measles is a highly infectious illness requiring herd immunity of 95% to interrupt transmission. Measles is targeted for elimination in China, which has not reached elimination goals despite high vaccination coverage. We developed a population profile of measles immunity among residents aged 0-49 years in Tianjin, China.

METHODS

Participants were either from community population registers or community immunization records. Measles IgG antibody status was assessed using dried blood spots. We examined the association between measles IgG antibody status and independent variables including urbanicity, sex, vaccination, measles history, and age.

RESULTS

2818 people were enrolled. The proportion measles IgG negative increased from 50.7% for infants aged 1 month to 98.3% for those aged 7 months. After 8 months, the age of vaccination eligibility, the proportion of infants and children measles IgG negative decreased. Overall, 7.8% of participants 9 months of age or older lacked measles immunity including over 10% of those 20-39 years. Age and vaccination status were significantly associated with measles IgG status in the multivariable model. The odds of positive IgG status were 0.337 times as high for unvaccinated compared to vaccinated (95% CI: 0.217, 0.524).

CONCLUSIONS

The proportion of persons in Tianjin, China immune to measles was lower than herd immunity threshold with less than 90% of people aged 20-39 years demonstrating protection. Immunization programs in Tianjin have been successful in vaccinating younger age groups although high immunization coverage in infants and children alone would not provide protective herd immunity, given the large proportion of non-immune adults.

Difficulties in eliminating measles and controlling rubella and mumps: a cross-sectional study of a first measles and rubella vaccination and a second measles, mumps, and rubella vaccination

Background

The reported coverage of the measles–rubella (MR) or measles–mumps–rubella (MMR) vaccine is greater than 99.0% in Zhejiang province. However, the incidence of measles, mumps, and rubella remains high. In this study, we assessed MMR seropositivity and disease distribution by age on the basis of the current vaccination program, wherein the first dose of MR is administered at 8 months and the second dose of MMR is administered at 18–24 months.

Methods

Cross-sectional serological surveys of MMR antibodies were conducted by collecting epidemiological data in Zhejiang province, China in 2011. In total, 1015 participants were randomly selected from two surveillance sites. Serum MMR-specific immunoglobulin G levels were tested by enzyme-linked immunosorbent assay. The geometric mean titers and seroprevalence with 95% confidence intervals (CIs) were calculated by age and gender. Proportions of different dose of vaccine by age by vaccine were also identified. Statistically significant differences between categories were assessed by the Chi-square test.

Results

Over 95% seroprevalence rates of measles were seen in all age groups except <7 months infants. Children aged 5–9 years were shown lower seropositivity rates of mumps while elder adolescences and young adults were presented lower rubella seroprevalence. Especially, rubella seropositivity was significantly lower in female adults than in male. Nine measles cases were unvaccinated or unknown vaccination history. Among them, 66.67% (6/9) patients were aged 20–29 years while 33.33% (3/9) were infants aged 8–12 months. In addition, 57.75% (648/1122) patients with mumps were children aged 5–9 years, and 50.54% (94/186) rubella cases were aged 15–39 years.

Conclusions

A timely two-dose MMR vaccination schedule is recommended, with the first dose at 8 months and the second dose at 18–24 months. An MR vaccination speed-up campaign may be necessary for elder adolescents and young adults, particularly young females.

Measles epidemic from 1951 to 2012 and vaccine effectiveness in Guangzhou, southern China

BACKGROUND

Since the National Expanded Program on Immunization was implemented in China, considerable progress has been made in reducing the incidence of measles. However, the incidence of measles increased again in 2004. Few post-marketing studies on measles vaccine effectiveness were reported in China. In this study, we aimed to describe the measles epidemic and to evaluate the effectiveness of the measles vaccine in Guangzhou, southern China.

METHODS

Based on the surveillance data for measles, we investigated the epidemiology during different periods between 1951 and 2012. We analyzed the clinical characteristics of laboratory-confirmed cases of measles between 2009 and 2012 and conducted a case-control study using test-negative cases as controls. We determined the protective effect of measles vaccine.

RESULTS

The highest annual incidence in Guangzhou was 2187.15/100,000 in 1964, and the lowest was 0.32/100,000 in 2011. The average incidence of measles from 1951 to 2012 was 306.27/100,000. There was a significant tendency of decline in recent years. From 2009 to 2012, there are 700 laboratory-confirmed cases were reported with an average onset age of 2.5 (median) years. The non-vaccinated target population (age<8 months and ≥ 15 years) accounted for 56.7% of the cases. The transient (non-resident) population accounted for 51.3% of the cases. Fewer cases were observed in the population targeted for measles vaccine (aged 8 months to 14 years). The effectiveness of a single dose of the measles vaccine was 89.1% (95% confidence interval (CI), 44.5-97.9), and the effectiveness of ≥ 2 doses of the measles vaccine was 97.8% (95% CI, 88.3-99.6) in children aged 8 months to 14 years old.

CONCLUSIONS

There is a significant overall decline in the incidence of measles (including clinical and laboratory confirmed cases) in the measles vaccine targeted population in Guangzhou. Two doses of measles vaccine are more effective than one dose in preventing measles in China. In order to accelerate the elimination of measles, vaccination should also be given to the transient and the non-vaccine targeted population.

The effects of weather conditions on measles incidence in Guangzhou, Southern China

BACKGROUND

Few studies were conducted to examine the effects of weather conditions on the incidence of measles.

METHODS

We used a distributed lag nonlinear model (DLNM) to analyze the relationship between meteorological factors and measles incidence in Guangzhou, China.

RESULTS

Nonlinear effects of temperature and relative humidity on measles incidence were observed. The relative risk (RR) for the measles incidence associated with the 75th percentile of mean temperature (27.9 °C) relative to the median of mean temperature (24.7 °C) was 1.00 (0.86,1.16) for lags 0-10 days. The RR for the measles incidence associated with the 25th percentile of relative humidity (64%) relative to the median of relative humidity (73%) was 1.36 (1.01,1.82) for lags 0-30 days. The wet effects and dry effects were larger in females than in males. The wet effects were generally increased with ages. Significantly negative effects of cold spells on measles incidence were observed.

CONCLUSION

Both hot and cold temperatures result in decreases in the incidence of measles, and low relative humidity is a risk factor of measles morbidity. An increased number of measles cases might occur before and after a cold spell. Our findings highlight the need to pay more attention to the weather transformation and improve the immunity of susceptible population for measles elimination. Catch-up vaccination campaigns should be initiated among young adults.

Age-related changes in serological susceptibility patterns to measles: results from a seroepidemiological study in Dongguan, China

The present study was performed to determine the seroprevalence of IgG measles antibodies in Dongguan residents (irrespective of vaccination status), to analyze the changes in age-related serological susceptibility patterns. A total of 1960 residents aged 0-60 years and 315 mother-infant pairs were studied. Serum IgG antibodies against measles virus were measured by ELISA. The overall seroprevalence was 93.4% in the general population in Dongguan, China. In subgroups aged 1-29 years who were likely vaccinated, there was a declining trend of seropositivity with age from 98.6% at 1-4 years to 85.7% at 20-29 years (P<0.0001). Seroprevalence were near or>95% in the older population (30-39 years and ≥ 40 years) who had not been immunized against measles. Age and sex were independent factors associated with seropositivity. Seroprevalence in pregnant women and their newborns was 87.0% and 84.1%, respectively. Our results suggest that the waning vaccine-induced immunity may be the main cause of increased serological susceptibility in young adults and young infants. An additional vaccination strategy that targets young adults is important for elimination of measles.

Cross-sectional surveys of measles antibodies in the Jiangsu Province of China from 2008 to 2010: the effect of high coverage with two doses of measles vaccine among children

BACKGROUND

Changes in the epidemiological characteristics of measles since 2007 appeared in the Jiangsu province. Although the reported coverage with two doses of measles vaccine was greater than 95% in most regions of the province, measles incidence remained high across the whole province. Cross-sectional serological surveys of measles antibodies in the Jiangsu province of China were conducted from 2008 to 2010 to assess and track population immunity.

METHODS

Measles-specific IgG levels were measured in serum samples using ELISA. GMTs and seroprevalence with 95% CIs were calculated by region, gender, and age. ANOVA and χ(2) tests were used to test for statistically significant differences between groups for GMT levels and seroprevalence, respectively.

RESULTS

Seroprevalence showed a significantly increasing trend annually (CMH χ(2) = 40.32, p<0.0001). Although the seroprevalence among children aged 2-15 years was consistently over 95%, vaccine-induced measles antibodies may wane over time. Measles seropositivity in the Jiangsu province was 91.7% (95% CI: 90.1-93.2%) in 2010. Among adults aged 15 to 29-year-olds, the seropositivity rate was 88.4% (95% CI: 82.7-92.8%).

CONCLUSIONS

Vaccination strategies may need to be adjusted depending on the individual age and regions, particularly individuals between the ages of 8 months-14 years old and 20-29 years old. Additional SIAs are likely required to eliminate measles in China.

Health of China's rural-urban migrants and their families: a review of literature from 2000 to 2012

BACKGROUND

Socioeconomic transformation in China at the beginning of the twenty-first century has led to rapid urbanization and accelerated rural-urban migration. As a result, the concerns about public health problems triggered by increasing internal population mobility have been more widely studied in recent years.

SOURCES OF DATA

Published data in Chinese and English on health of migrants and their families in mainland China from 2000 to 2012.

AREAS OF AGREEMENT

The shifting patterns of disease distribution due to rural-urban migration, health equity and health reform strategies that cater for this specific yet substantial subpopulation are outstanding concerns. Infectious diseases, mental health, occupational health and women's health are emerging public health priorities related to migration.

AREAS OF CONTROVERSY

The high mobility and large numbers of Chinese rural-urban migrants pose challenges to research methods and the reliability of evidence gained.

GROWING POINTS

While the theme of working migrants is common in the literature, there have also been some studies of health of those left behind but who often remain unregistered. Migration within China is not a single entity and understanding the dynamics of new and emerging societies will need further study.

AREAS TIMELY FOR DEVELOPING RESEARCH

Social, economic, emotional, environmental and behavioural risk factors that impact on health of migrants and their families call for more attention from health policy-makers and researchers in contemporary China.

Waning immunity to measles in young adults and booster effects of revaccination in secondary school students

The increasing proportions of adult cases were observed in the recent measles outbreaks in Zhejiang Province, China. In order to identify the high-risk age groups of measles for targeted intervention, a seroprevalence survey of measles antibody was conducted among 1961 participants aged 0-60 years randomly selected by age-stratified purpose sampling, and the effect of revaccination program in secondary school was evaluated in Zhejiang Province. The adjusted overall seropositivity rate of measles was 88% (95% confidence interval [CI]: 86-89%) with geometric mean titers (GMT), 976±86 mIU/ml. The seropositivity rate of measles was significantly lower in subjects aged 15-19 years than aged 5-9 years (90% vs 96%, χ(2)=5.21, p=0.022). Both seropositivity rate and GMT level of measles were higher in participants aged 10-14 years with ≥2 doses MCV than those with only 1 dose (95% vs 81%, 1276 mIU/ml vs 666 mIU/ml). The seropositivity rate increased from 91% to 100% after revaccination with MCV among 184 secondary school students. The proportions of measles cases aged ≥15 years were reduced gradually (χ(2)=55.47, p=0.000) from 2009 to 2011 after implementing the revaccination campaign on secondary school students since 2008. Our findings strongly suggested that a revaccination opportunity with MCV for adolescents helps to improve the population immunity, and it can be conducted effectively and practically in secondary school students.

Recent resurgence of measles in a community with high vaccination coverage

Even though 2-dose measles vaccination coverage rate was maintained at more than 95%, the largest measles outbreaks since 1996 still occurred in Wuhu city, P R China. A total of 916 cases were reported during 2005-2010. The annual incidence was 6.7 cases per 100,000 population with the peak incidence of 17.6 cases per 100,000 population in 2008. The highest age-specific incidence rate was 222.1 per 100,000 population and occurred in infants aged between 8 and 12 months; the second was 151.9 per 100,000 population in infants aged <8 months. Also, 200 cases occurred in those aged to 22 to 30 years old, accounting for 21.8% of total cases, with the age-specific incidence being 12.8 per 100,000 population. The characteristics related to age distribution have changed in recent measles outbreaks. It underlines the need for vaccination of susceptible young adults and timely administration of the first dose of the measles vaccine.

Seroprevalence of measles among children affected by national measles elimination program in Korea, 2010

BACKGROUND

Following the implementation of national measles elimination plan in Korea, the elimination was declared in 2006. In order to sustain the elimination, high population immunity should be continuously monitored. To evaluate the current age-related susceptibility within the Korean population, we conducted the seroprevalence in children and adolescents who were affected by the national measles elimination plan.

METHODS

We used residual serum specimens to measure measles specific IgG and geometric mean titer (GMT) in birth cohorts 2007-2008 and 1997-2003. Among birth cohorts, 2007-2008 cohorts were grouped to evaluate the timeliness of first dose of MMR, 1994-2003 cohorts were grouped to evaluate the effect of keep-up MMR2 campaign, and 1992-1993 cohorts were grouped to evaluate the effect of catch-up campaign in 2001.

RESULTS

Overall, measles seropositivity rate was 86%. The highest seroprevalence of measles IgG was in birth cohorts 2007-2008. Measles seropositivity declined continuously in age groups. The birth cohorts 1994-1996 showed significantly lower levels of seropositivity and GMT than did the other birth cohorts.

CONCLUSION

Despite efforts to eliminate measles for the past 10 years in Korea, our study revealed specific birth cohorts remaining at risk for transmission. The adolescents born during 1994-1996 had the lowest measles seropositivity levels, and might represent a 'pocket' that has potential at increased risk for measles transmission. Further discussion for follow-up immunization should be placed for consideration in the near future.