Measles risk groups in Spain: implications for the European measles-elimination target

Seroprevalence of viral infectious diseases and associated factors in Korean patients with inflammatory bowel diseases

BACKGROUND/AIMS

Data on the immunoprotective status against measles, mumps, rubella, varicella zoster virus (VZV), hepatitis A virus (HAV), and Epstein-Barr virus (EBV) infection in patients with inflammatory bowel disease (IBD) are still lacking. Therefore, we investigated the seropositivity rates for viral infectious diseases and the associated factors in Korean patients with IBD.

METHODS

In this retrospective cohort study, serum immunoglobulin G antibody positivity rates against measles virus, mumps virus, rubella virus, VZV, HAV, and EBV viral capsid antigen (VCA) were measured in patients with Crohn's disease or ulcerative colitis (UC) who first visited the IBD clinic. Seropositivity rates and their associated factors were analyzed.

RESULTS

Between January 2016 and December 2018, 263 patients were enrolled (male, 167 [67.3%]; UC, 134 [50.9%]). The median age at serological test was 30 years (interquartile range, 22 to 46). The seropositivity rates were 84.0%, 85.2%, 66.5%, 87.4%, 50.0%, and 93.7% for measles, mumps, rubella, VZV, HAV, and EBV, respectively. Younger age at serological test was associated with seronegative status for measles (adjusted odds ratio [aOR], 0.92; 95% confidence interval [CI], 0.88 to 0.96), VZV (aOR, 0.83; 95% CI, 0.74 to 0.93), and HAV (aOR, 0.93; 95% CI, 0.91 to 0.95). Furthermore, IBD type-UC was associated with seronegative status against VZV (aOR, 0.33; 95% CI, 0.11 to 0.99).

CONCLUSION

Seropositivity rates for common viral infectious diseases in Korean patients with IBD were similar to those of the general population. In the younger age group, protective immunity against measles, VZV, and HAV is required, with proper vaccination, as necessary.

Combining serological and contact data to derive target immunity levels for achieving and maintaining measles elimination

BACKGROUND

Vaccination has reduced the global incidence of measles to the lowest rates in history. However, local interruption of measles virus transmission requires sustained high levels of population immunity that can be challenging to achieve and maintain. The herd immunity threshold for measles is typically stipulated at 90-95%. This figure does not easily translate into age-specific immunity levels required to interrupt transmission. Previous estimates of such levels were based on speculative contact patterns based on historical data from high-income countries. The aim of this study was to determine age-specific immunity levels that would ensure elimination of measles when taking into account empirically observed contact patterns.

METHODS

We combined estimated immunity levels from serological data in 17 countries with studies of age-specific mixing patterns to derive contact-adjusted immunity levels. We then compared these to case data from the 10 years following the seroprevalence studies to establish a contact-adjusted immunity threshold for elimination. We lastly combined a range of hypothetical immunity profiles with contact data from a wide range of socioeconomic and demographic settings to determine whether they would be sufficient for elimination.

RESULTS

We found that contact-adjusted immunity levels were able to predict whether countries would experience outbreaks in the decade following the serological studies in about 70% of countries. The corresponding threshold level of contact-adjusted immunity was found to be 93%, corresponding to an average basic reproduction number of approximately 14. Testing different scenarios of immunity with this threshold level using contact studies from around the world, we found that 95% immunity would have to be achieved by the age of five and maintained across older age groups to guarantee elimination. This reflects a greater level of immunity required in 5-9-year-olds than established previously.

CONCLUSIONS

The immunity levels we found necessary for measles elimination are higher than previous guidance. The importance of achieving high immunity levels in 5-9-year-olds presents both a challenge and an opportunity. While such high levels can be difficult to achieve, school entry provides an opportunity to ensure sufficient vaccination coverage. Combined with observations of contact patterns, further national and sub-national serological studies could serve to highlight key gaps in immunity that need to be filled in order to achieve national and regional measles elimination.

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.

Measles among migrants in the European Union and the European Economic Area

Aims: Progress towards meeting the goal of measles elimination in the EU and the European Economic Area (EEA) by 2015 is being obstructed, as some children are either not immunized on time or never immunized. One group thought to be at increased risk of measles is migrants; however, the extent to which this is the case is poorly understood, due to a lack of data. This paper addresses this evidence gap by providing an overview of the burden of measles in migrant populations in the EU/EEA. Methods: Data were collected through a comprehensive literature review, a country survey of EU/EEA member states and information from measles experts gathered at an infectious disease workshop. Results: Our results showed incomplete data on measles in migrant populations, as national surveillance systems do not systematically record migration-specific information; however, evidence from the literature review and country survey suggested that some measles outbreaks in the EU/EEA were due to sub-optimal vaccination coverage in migrant populations. Conclusions: We conclude that it is essential that routine surveillance of measles cases and measles, mumps and rubella (MMR) vaccination coverage become strengthened, to capture migrant-specific data. These data can help to inform the provision of preventive services, which may need to reach out to vulnerable migrant populations that currently face barriers in accessing routine immunization and health services.

Lessons and challenges for measles control from unexpected large outbreak, Malawi

Supplementary immunization activities are crucial to reduce the number of susceptible children.

Despite high reported coverage for routine and supplementary immunization, in 2010 in Malawi, a large measles outbreak occurred that comprised 134,000 cases and 304 deaths. Although the highest attack rates were for young children (2.3%, 7.6%, and 4.5% for children <6, 6–8, and 9–11 months, respectively), persons >15 years of age were highly affected (1.0% and 0.4% for persons 15–19 and >19 years, respectively; 28% of all cases). A survey in 8 districts showed routine coverage of 95.0% for children 12–23 months; 57.9% for children 9–11 months; and 60.7% for children covered during the last supplementary immunization activities in 2008. Vaccine effectiveness was 83.9% for 1 dose and 90.5% for 2 doses. A continuous accumulation of susceptible persons during the past decade probably accounts for this outbreak. Countries en route to measles elimination, such as Malawi, should improve outbreak preparedness. Timeliness and the population chosen are crucial elements for reactive campaigns.

Measles outbreak in Europe: susceptibility of infants too young to be immunized

As women vaccinated against measles transfer low amounts of antibodies, an increasing number of infants lack early protection through maternal antibodies until being immunised themselves. This paper reviews the literature on disease burden of measles in the population too young to be immunized according to the respective national recommendations during recent outbreaks in EU and EEA/EFTA countries. In addition, specific control strategies adopted to protect this young population are reviewed. Pubmed, Unbound Medline, Web of Knowledge and the Eurosurveillance database were searched using MESH terms: measles and epidemiology, measles and infants, prevalence of measles, measles and outbreaks and measles and epidemic. Additionally, data from Euvac.net and ECDC were consulted. Databases were searched from January 2001 to September 2011. Fifty-three papers were included in the analysis. The percentage of all measles cases during outbreaks affecting young infants ranged from 0.25% to 83.0%. Specific control strategies were adopted: e.g. administration of the first or second vaccine dose earlier than recommended. Infants younger than 12 months are often involved in measles outbreaks, and advancing the first vaccine dose could reduce the burden of disease. However, immunization before 9 months of age is not systematically recommended because of dysmature humoral immune responses of infants. High coverage and timely administration of the recommended series of vaccines are the most important measures to decrease measles incidence and measles circulation and protect vulnerable infants from infection.

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.

[Susceptibility to measles and varicella in healthcare workers in a tertiary hospital in Catalonia]

INTRODUCTION

To estimate the susceptibility to measles and varicella (chickenpox) in healthcare workers in a public tertiary level teaching hospital, in Catalonia.

METHODS

A prevalence study was conducted from January 2006 to December 2008 on 2,752 workers who had serology performed for the determination of measles or varicella by ELISA test during a health examination. Data were analysed by, sex, age, professional category and work unit.

RESULTS

A total of 153 healthcare workers were susceptible to measles and 187 to varicella. The susceptibility of healthcare workers to measles was 6.04% (95% CI: 5.78 to 6.30), and to varicella it was 7.45% (95% CI: 7.14 to 7.75). The highest susceptibility to measles was in resident physicians with 14% (95% CI: 10.8 to 18.5). In high-risk services, where highly immunocompromised patients are attended, the susceptibility of workers was slightly higher than the rest to measles (6.32% vs 5.93%) and varicella (8.34% vs 7.09%). Healthcare workers born after 1980 were 20 times (95% CI: 11.0 to 37.2) more likely to be susceptible to measles, and 2 times (95% CI: 1.2 to 3.2) more likely to be susceptible to varicella than those those born before 1965.

CONCLUSIONS

The susceptibility to measles in healthcare workers in our centre is higher in younger cohorts, with values higher than expected in a community with high vaccination coverage against measles, mumps, rubella vaccine (MMR) in the paediatric population for many years.

MMR vaccine effectiveness in an outbreak that involved day-care and primary schools

OBJECTIVE

In 2006, a large measles outbreak occurred in Catalonia (Spain), where the immunization schedule included two doses of MMR vaccine at 15 months and 4 years. The aim of this study was to investigate the vaccine effectiveness (VE) of MMR in children attending day-care and pre-school centres and to estimate the number of cases that would have been avoided by administering the first dose of MMR at 12 months.

METHODS

A retrospective cohort study was carried out between October 2006 and January 2007 in day-care and pre-school centres with confirmed measles cases. VE was calculated in children aged ≥15 months without previous measles infection. Cases avoided by advancing the first dose of MMR to 12 months were estimated by calculating the basic and effective reproduction number in centres where transmission outside the class was observed.

RESULTS

Fifteen centres and 1394 children were included. There were 77 confirmed cases (attack rate=5.5%). Vaccination coverage of the 1121 children aged ≥15 months was 91.6% and VE was 96% (95%CI 89-98%). There were 33 (41%) cases in the 81 children aged 12-14 months. Advancing the first dose to 12 months would have prevented 74 cases (91.5%) and lowered the attack rate from 41% to 8.6%.

CONCLUSIONS

Over 90% of cases in children aged 12-14 months would have been avoided by MMR administration at 12 rather than 15 months. We strongly recommend advancing the first dose of MMR to 12 months in order to reduce the risk of measles outbreaks.