Effect of vaccination on severity and infectiousness of measles during an outbreak in the Netherlands, 2013-2014.

An outbreak of measles in the Netherlands in 2013-2014 provided an opportunity to assess the effect of MMR vaccination on severity and infectiousness of measles.Measles is notifiable in the Netherlands. We used information on vaccination, hospitalisation, complications, and most likely source(s) of infection from cases notified during the outbreak. When a case was indicated as a likely source for at least one other notified case, we defined it as infectious. We estimated the age-adjusted effect of vaccination on severity and infectiousness with logistic regression.Of 2676 notified cases, 2539 (94.9%) were unvaccinated, 121 (4.5%) were once-vaccinated and 16 (0.6%) were at least twice-vaccinated; 328 (12.3%) cases were reported to have complications and 172 (6.4%) cases were hospitalised. Measles in twice-vaccinated cases led less often to complications and/or hospitalisation than measles in unvaccinated cases (0% and 14.5%, respectively, aOR 0.1 (95% CI 0-0.89), P = 0.03). Of unvaccinated, once-vaccinated and twice-vaccinated cases, respectively, 194 (7.6%), seven (5.1%) and 0 (0%) were infectious. These differences were not statistically significant (P > 0.05).Our findings suggest a protective effect of vaccination on the occurrence of complications and/or hospitalisation as a result of measles and support the WHO recommendation of a two-dose MMR vaccination schedule.

The tip of the iceberg: incompleteness of measles reporting during a large outbreak in The Netherlands in 2013-2014.

Measles is a notifiable disease, but not everyone infected seeks care, nor is every consultation reported. We estimated the completeness of reporting during a measles outbreak in The Netherlands in 2013-2014. Children below 15 years of age in a low vaccination coverage community (n = 3422) received a questionnaire to identify measles cases. Cases found in the survey were matched with the register of notifiable diseases to estimate the completeness of reporting. Second, completeness of reporting was assessed by comparing the number of susceptible individuals prior to the outbreak with the number of reported cases in the surveyed community and on a national level.We found 307 (15%) self-identified measles cases among 2077 returned questionnaires (61%), of which 27 could be matched to a case reported to the national register; completeness of reporting was 8.8%. Based on the number of susceptible individuals and number of reported cases in the surveyed community and on national level, the completeness of reporting was estimated to be 9.1% and 8.6%, respectively. Estimating the completeness of reporting gave almost identical estimates, which lends support to the credibility and validity of both approaches. The size of the 2013-2014 outbreak approximated 31 400 measles infections.

Current prevalence of chronic hepatitis B and C virus infection in the general population, blood donors and pregnant women in the EU/EEA: a systematic review.

This systematic review aimed at estimating chronic hepatitis B (HBV) and C virus (HCV) prevalence in the European Union (EU) and Economic Area (EEA) countries in the general population, blood donors and pregnant women. We searched PubMed©, Embase© and Cochrane Library databases for reports on HBV and HCV prevalence in the general population and pregnant women in EU/EEA countries published between 2005 and 2015. Council of Europe data were used for HBV and HCV blood donor prevalence. HBV general population estimates were available for 13 countries, ranging from 0·1% to 4·4%. HCV general population estimates were available for 13 countries, ranging from 0·1% to 5·9%. Based on general population and blood donor estimates, the overall HBV prevalence in the EU/EEA is estimated to be 0·9% (95% CI 0·7-1·2), corresponding to almost 4·7 million HBsAg-positive cases; and the overall HCV prevalence to be 1·1% (95% CI 0·9-1·4), equalling 5·6 million anti-HCV-positive cases. We found wide variation in HCV and HBV prevalence across EU/EEA countries for which estimates were available, as well as variability between groups often considered a proxy for the general population. Prevalence estimates are essential to inform policymaking and public health practice. Comparing to other regions globally, HBV and HCV prevalence in the EU/EEA is low.

Tolerability of Early Measles-Mumps-Rubella Vaccination in Infants Aged 6-14 Months During a Measles Outbreak in The Netherlands in 2013-2014.

BACKGROUND: In 2013-2014, a measles outbreak spread through the Netherlands. To protect young infants, measles-mumps-rubella (MMR) vaccination was offered to those aged 6-14 months in municipalities with routine first-dose MMR vaccine coverage of <90%. We assessed the tolerability of this early administration of MMR vaccine. METHODS: After study entry (n = 1866), parents of eligible infants (n = 10 097) completed a questionnaire (n = 1304). For infants who received an early MMR vaccine dose (n = 962), we asked for information about adverse events (AEs) associated with the dose. AE frequencies were compared between infants aged 6-8, 9-11, and 12-14 months. Using multivariable logistic regression, we assessed the association between the risk of AEs and age at early MMR vaccination. RESULTS: The response rate was 13%. Parents of 59 infants (6.1%) and 350 infants (36.4%) who received early MMR vaccination reported local and systemic AEs, respectively. Parents of infants vaccinated at 6-8 months of age reported systemic AEs less frequently (32%) than parents of children vaccinated at 9-11 months (45%) and 12-14 months (43%) of age (P= <.001). For local AEs, there were no differences (5%, 7%, and 10%, respectively;P= .08). Compared with vaccination at 6 months, all older infants except those aged 14 months showed an increased risk for any AE and for systemic AEs starting 5-12 days after vaccination. CONCLUSIONS: Early MMR vaccination is well tolerated, with the lowest AE frequencies found in infants aged 6-8 months. It is a safe intervention for protecting young infants against measles.

Performance of a bedside test for tetanus immunity: results of a cross-sectional study among three EDs in the Netherlands in 2012-2013.

INTRODUCTION: Despite sustained high vaccination coverage and a national guideline by the Health Council (HC-guideline) on tetanus postexposure prophylaxis (T-PEP), tetanus sporadically occurs in the Netherlands. This study aims to assess the added value of a bedside test for tetanus immunity (Tetanos Quick Stick (TQS); Ingen BioSciences Group, France), in the context of routine T-PEP in two adult cohorts: those born before introduction of tetanus toxoid vaccination in the National Immunization Programme (NIP) in 1957 (pre-NIP-cohort; n=196) and those born after (NIP-cohort; n=405). METHODS: Adults included at the time of visiting one of three participating EDs received T-PEP as per routine recommendations. Subsequently, a nurse performed the TQS and filled in a questionnaire. We compared the indication for T-PEP based on TQS results with those based on the HC-guideline and with actually administration of T-PEP, stratified by cohort. RESULTS: Among the pre-NIP and NIP-cohort, 16% and 9%, respectively, received T-PEP, while this was not indicated based on the HC-guideline. Furthermore, 8% and 7%, respectively, did not get T-PEP, although it was indicated by the guideline. Comparing the indication derived from the HC-guideline with TQS result found that 22% (pre-NIP-cohort) and 8% (NIP-cohort) were not eligible for T-PEP according to the HC-guideline but had a negative TQS. Conversely, 36% (pre-NIP-cohort) and 73% (NIP-cohort) were eligible for T-PEP according to the HC-guideline but had positive TQS, indicating sufficient tetanus protection. CONCLUSION: Use of the TQS would allow better targeting of T-PEP. Furthermore, stricter adherence to the HC-guideline can prevent overimmunisation and decrease the risk of tetanus.

High risk of a large measles outbreak despite 30 years of measles vaccination in The Netherlands.

Our aim was to assess progress towards measles elimination from The Netherlands by studying humoral measles immunity in the Dutch population. A population-based seroepidemiological study was conducted in 2006-2007 (N = 7900). Serum samples were analysed by a bead-based multiplex immunoassay. IgG levels ⩾0·2 IU/ml were considered protective. The overall seroprevalence in the Dutch population was 96%. However, 51% of socio-geographically clustered orthodox Protestant individuals aged <10 years were susceptible. Infants might be susceptible to measles between ages 4 months and 14 months, the age at which maternal antibodies have disappeared and the first measles, mumps, rubella (MMR) vaccination is administered, respectively. Waning of antibody concentrations was slower after the second MMR vaccination than after the first. The Netherlands is at an imminent risk of a measles outbreak in the orthodox Protestant minority. To prevent subsequent transmission to the general population, efforts to protect susceptible age groups are needed.

Smoking and older age associated with mumps in an outbreak in a group of highly-vaccinated individuals attending a youth club party, the Netherlands, 2012.

We describe a mumps outbreak in a highly-vaccinated population attending a party at a youth club. In a retrospective cohort study with 60 of approximately 100 participants responding, vaccination status was verified for 58/59 respondents, of whom 54 were vaccinated twice and four once. The attack rate was 22% (13 cases, all vaccinated), with smoking at the party (risk ratio (RR) 3.1; 95% confidence interval (CI): 1.6­6.0, p=0.001) and age ≥21 years (RR 4.7; 95% CI: 2.1­10.2, p<0.0001) as risk factors for disease in the binominal regression analysis. Mild upper respiratory illness was also highly prevalent in those who did not meet the mumps case definition (n=46) after the party, suggesting that mumps virus infection may cause mild disease in vaccinated individuals. Our investigation adds toevidence that crowded social events and smoking may facilitate spread of mumps virus among vaccinated populations, with waning immunity playing a role. The suggestion that mumps virus infection in vaccinated individuals may manifest as mild upper respiratory illness could have implications for transmission and warrants further investigation.

Exceptionally low rotavirus incidence in the Netherlands in 2013/14 in the absence of rotavirus vaccination.

An unexpected drop in rotavirus (RV) detections was observed in the Netherlands in 2014, without RV vaccination. The estimated decrease in RV detections and gastroenteritis consultations in under five year-olds, in January-April 2014, compared to the same months in previous years, was 72% and 36%, respectively. The low birth rate, mild winter, high RV incidence in the previous year and the introduction of RV vaccination in neighbouring countries may have contributed to this decrease.

Acceptance and timeliness of post-exposure vaccination against mpox in high-risk contacts, Amsterdam, the Netherlands, May-July 2022.

BACKGROUND: May 2022, several countries reported mpox outbreaks among men-who-have-sex-with-men. In the Netherlands, high-risk contacts were offered the third-generation smallpox vaccine as post-exposure-prophylaxis (PEP) within 4 but maximum 14 days after exposure. We investigated their PEP acceptance, timeliness of uptake and development of mpox for the region of the Public Health Service (PHS) Amsterdam. METHODS: High-risk contacts identified during 20 May-22 July 2022 were included. Contacts were followed-up 21 days after exposure and classified as: no patient (no mpox symptoms or orthopoxvirus PCR-negative) or mpox patient (clinically suspected mpox or orthopoxvirus PCR-positive). We calculated time intervals between date of last exposure and first PHS consultation, PEP administration, and symptom onset. RESULTS: Two-hundred-ninety contacts were at high-risk of mpox predominantly due to sexual and/or direct skin-skin contact (212/290, 73 %). First PHS consultation was a median of 5 (IQR 3, 7) days after exposure, at which point 26/290 (9 %) contacts were ineligible for PEP. 84 % (223/264) of contacts eligible for PEP, received PEP within a median of 6 (IQR 3, 8) days after exposure. Of 282 contacts (missing outcome n = 8) 38 (14 %) developed mpox a median of 7 (IQR 5, 12) days after exposure, of whom 50 % (19/38) developed mpox before their first PHS consultation. Among contacts eligible for PEP, 2/38 (5 %) unvaccinated and 16/218 (7 %) vaccinated contact developed mpox. CONCLUSIONS: PEP acceptance among contacts of mpox patients was high. However, PEP timeliness was inadequate. Half of contacts received PEP 6 or more days after exposure, and half of contacts who developed mpox had an onset prior to their first PHS consultation. Estimating PEP vaccine effectiveness is problematic due to the timeliness of PEP and the time it takes to generate vaccine-induced immunity. It is important to assess how PEP timeliness may improve and to promote pre-exposure vaccination to control mpox outbreaks.

The daily updated Dutch national database on COVID-19 epidemiology, vaccination and sewage surveillance.

The Dutch national open database on COVID-19 has been incrementally expanded since its start on 30 April 2020 and now includes datasets on symptoms, tests performed, individual-level positive cases and deaths, cases and deaths among vulnerable populations, settings of transmission, hospital and ICU admissions, SARS-CoV-2 variants, viral loads in sewage, vaccinations and the effective reproduction number. This data is collected by municipal health services, laboratories, hospitals, sewage treatment plants, vaccination providers and citizens and is cleaned, analysed and published, mostly daily, by the National Institute for Public Health and the Environment (RIVM) in the Netherlands, using automated scripts. Because these datasets cover the key aspects of the pandemic and are available at detailed geographical level, they are essential to gain a thorough understanding of the past and current COVID-19 epidemiology in the Netherlands. Future purposes of these datasets include country-level comparative analysis on the effect of non-pharmaceutical interventions against COVID-19 in different contexts, such as different cultural values or levels of socio-economic disparity, and studies on COVID-19 and weather factors.

Prevalence of hepatitis B virus infection in The Netherlands in 1996 and 2007.

We aimed to assess differences in the prevalence of hepatitis B virus (HBV) infection in The Netherlands between 1996 and 2007, and to identify risk factors for HBV infection in 2007. Representative samples of the Dutch population in 1996 and 2007 were tested for antibodies to hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg) and HBV-DNA. In 2007, the weighted anti-HBc prevalence was 3·5% (95% CI 2·2-5·5) and the HBsAg prevalence was 0·2% (95% CI 0·1-0·4). In indigenous Dutch participants, the anti-HBc prevalence was lower in 2007 than in 1996 (P=0·06). First-generation migrants (FGMs) had a 13-fold greater risk of being HBsAg- and/or HBV-DNA-positive than indigenous Dutch participants. In indigenous Dutch participants, risk factors for anti-HBc positivity were older age and having received a blood product before 1990. In FGMs, being of Asian origin was a risk factor. In second-generation migrants, having a foreign-born partner and injecting drug use were risk factors. FGMs are the main target group for secondary HBV prevention in The Netherlands.

Vaccine effectiveness against COVID-19 related hospital admission in the Netherlands: A test-negative case-control study.

INTRODUCTION: Real-world vaccine effectiveness (VE) estimates are essential to identify potential groups at higher risk of break-through infections and to guide policy. We assessed the VE of COVID-19 vaccination against COVID-19 hospitalization, while adjusting and stratifying for patient characteristics. METHODS: We performed a test-negative case-control study in six Dutch hospitals. The study population consisted of adults eligible for COVID-19 vaccination hospitalized between May 1 and June 28, 2021 with respiratory symptoms. Cases were defined as patients who tested positive for SARS-CoV-2 by PCR during the first 48 h of admission or within 14 days prior to hospital admission. Controls were patients tested negative at admission and did not have a positive test during the 2 weeks prior to hospitalization. VE was calculated using multivariable logistic regression, adjusting for calendar week, sex, age, comorbidity and nursing home residency. Subgroup analysis was performed for age, sex and different comorbidities. Secondary endpoints were ICU-admission and mortality. RESULTS: 379 cases and 255 controls were included of whom 157 (18%) were vaccinated prior to admission. Five cases (1%) and 40 controls (16%) were fully vaccinated (VE: 93%; 95% CI: 81 - 98), and 40 cases (11%) and 70 controls (27%) were partially vaccinated (VE: 70%; 95% CI: 50-82). A strongly protective effect of vaccination was found in all comorbidity subgroups. No ICU-admission or mortality were reported among fully vaccinated cases. Of unvaccinated cases, mortality was 10% and 19% was admitted at the ICU. CONCLUSION: COVID-19 vaccination provides a strong protective effect against COVID-19 related hospital admission, in patients with and without comorbidity.

Mumps epidemic in orthodox religious low-vaccination communities in the Netherlands and Canada, 2007 to 2009.

We assessed the epidemiological characteristics of a mumps virus epidemic (genotype D) that occurred in the Netherlands between August 2007 and May 2009 and its association with a subsequent mumps outbreak in Canada. In the Netherlands, five data sources were used: notifications (only mandatory since the end of 2008) (56 cases), laboratory confirmation data (177 cases), a sentinel general practitioner (GP) database (275 cases), hospitalisation data (29 cases) and weekly virological reports (96 cases). The median age of cases in the notification, laboratory and GP databases ranged from 13 to 15 years. The proportion of cases that were unvaccinated ranged from 65% to 85% in the notification, laboratory and GP databases. Having orthodox Protestant beliefs was the main reason for not being vaccinated. In Canada, a mumps virus strain indistinguishable from the Dutch epidemic strain was detected between February and October 2008 in an orthodox Protestant community with historical and family links to the affected community in the Netherlands, suggesting that spread to Canada had occurred. Prevention and control of vaccine-preventable diseases among population subgroups with low vaccination coverage remains a priority.

Impact analysis of rotavirus vaccination in various geographic regions in Western Europe.

BACKGROUND: Universal mass vaccination (UMV) against rotavirus has been implemented in many but not all European countries. This study investigated the impact of UMV on rotavirus incidence trends by comparing European countries with UMV: Belgium, England/Wales and Germany versus countries without UMV: Denmark and the Netherlands. METHODS: For this observational retrospective cohort study, time series data (2001-2016) on rotavirus detections, meteorological factors and population demographics were collected. For each country, several meteorological and population factors were investigated as possible predictors of rotavirus incidence. The final set of predictors were incorporated in negative binomial models accounting for seasonality and serial autocorrelation, and time-varying incidence rate ratios (IRR) were calculated for each age group and country separately. The overall vaccination impact two years after vaccine implementation was estimated by pooling the results using a random effects meta-analyses. Independent t-tests were used to compare annual epidemics in the pre-vaccination and post-vaccination era to explore any changes in the timing of rotavirus epidemics. RESULTS: The population size and several meteorological factors were predictors for the rotavirus epidemiology. Overall, we estimated a 42% (95%-CI 23;56%) reduction in rotavirus incidence attributable to UMV. Strongest reductions were observed for age-groups 0-, 1- and 2-years (IRR 0.47, 0.48 and 0.63, respectively). No herd effect induced by UMV in neighbouring countries was observed. In all UMV countries, the start and/or stop and corresponding peak of the rotavirus season was delayed by 4-7 weeks. CONCLUSIONS: The introduction of rotavirus UMV resulted in an overall reduction of 42% in rotavirus incidence in Western European countries two years after vaccine introduction and caused a change in seasonal pattern. No herd effect induced by UMV neighbouring countries was observed for Denmark and the Netherlands.

Persistent and transient hepatitis B virus (HBV) infections in children born to HBV-infected mothers despite active and passive vaccination.

Combined passive and active immunization for newborns very effectively prevents perinatal hepatitis B virus (HBV) infections. In the Netherlands, babies born to hepatitis B surface antigen (HBsAg)-positive women receive passive immunization with hepatitis B and at least three active HBsAg vaccinations. Serological testing for the presence of HBV markers was offered for all infants born to HBsAg-positive mothers between January 2003 and July 2007, after completion of their vaccination schedule. About 75% of the infants (n = 1743) completed their HB-vaccination schedule and participated in the serologic evaluation. Twelve of them (0.7%) were found to be HBV infected. Furthermore, we identified three older children with high levels of anti-HBc, anti-HBs and anti-HBe, while they were HBsAg and HBV DNA negative. This serologic profile is evidence for a resolved HBV infection. In the group of older children (1.5-5 years of age, n = 728), about half of the HBV-infected children (3 of 7) had already cleared their infection at the time of sampling. For a proper evaluation of the efficacy of a new intervention programme to prevent vertical HBV transmission, it is also important to analyse the HBV markers in serum collected when the children are older than 1.5 years. In a programmatic setting, all children born to HBV-infected mothers should be tested not only for the level of anti-HBs but also for the absence of HBsAg, because 2 of the 12 HBV-infected children (17%) had a high level of anti-HBs.

A cost-utility analysis of antenatal screening to prevent congenital rubella syndrome.

In low vaccination coverage regions (LVR) in The Netherlands people often reject participation in the National Immunization Programme for religious reasons. During a rubella epidemic in 2004-2005, 32 pregnant women were notified with rubella, and 11 babies were born with defects related to maternal infection. This study presents a cost-utility analysis of a screening and vaccination programme for rubella focusing on three scenarios: (1) screening non-vaccinated pregnant women in LVR; (2) screening all pregnant women in LVR; (3) screening all non-vaccinated pregnant women in The Netherlands (including pregnant first-generation non-Western immigrant women). Cost-utility was estimated over a 16-year period which included two rubella outbreaks. Observed complications from the 2004-2005 epidemic were used to estimate average cost savings and quality-adjusted life-years (QALY) gained. The programme would be cost-effective (euro1100/QALY gained) when assuming an acceptability of vaccination of 20% in women belonging to orthodox protestant risk groups.

Ongoing mumps outbreak in a student population with high vaccination coverage, Netherlands, 2010.

Since December 2009, mumps incidence has increased in the Netherlands. As of 20 April 2010, 172 cases have been notified on the basis of laboratory confirmation or linkage to a laboratory-confirmed case. Of these, 112 were students, the majority of whom had been vaccinated (81%). Although outbreaks in vaccinated populations have been described before, risk factors for exposure and susceptibility, and dose-dependent vaccine effectiveness in a student population of this nature are relatively unknown.

Epidemiology and control of influenza A(H1N1)v in the Netherlands: the first 115 cases.

Introductions of the new influenza A(H1N1) variant virus in the Netherlands led to enhanced surveillance and infection control. By 24 June 2009, 115 cases were reported, of whom 44% were indigenously acquired. Severity of disease is similar to reports elsewhere. Our point estimate of the effective reproductive number (Re) for the initial phase of the influenza A(H1N1)v epidemic in the Netherlands was below one. Given that the Re estimate is based on a small number of indigenous cases and a limited time period, it needs to be interpreted cautiously.

[Vaccination against pneumococci and hepatitis B in the Dutch National Immunisation Programme]. / Pneumokokken- en hepatitis B-vaccinatie in het Rijksvaccinatieprogramma.

All infants in the Netherlands, which are born after March 2006, receive additional vaccinations at the age of 2, 3, 4 and 11 months to protect them against pneumococcal infections. During the same visit to a consultation bureau, the children also receive a combination vaccine against diphtheria, pertussis, tetanus, poliomyelitis and Haemophilus influenzae (DTPa-IPV-Hib). Children of which at least one parent was born in a country where hepatitis B occurs relatively often are also vaccinated in the Netherlands against hepatitis B. This currently pertains to about 15% of all newborns. These children now receive a new combination vaccine in which a hepatitis B component has been added to the DTPa-IPV-Hib components. They will receive this combination vaccine 4 times. This combination vaccine is given during the same visit as the pneumococcal vaccination. Although pneumococcal vaccination may have a somewhat negative effect on the immune response to hepatitis B, it is expected that the new 4-fold vaccination schedule will induce good and long-lasting protection against hepatitis B in the vast majority of the children. About 700 children are born out of mothers infected with hepatitis B each year in the Netherlands. In the new vaccination schedule, they now receive 5 active vaccinations against hepatitis B and are examined serologically on an individual basis in order to detect breakthrough infections. This will also generate greater insight into the efficacy of the different vaccination schemes and intervention programmes to prevent vertical transmission of the virus.

[Rubella epidemic in the Netherlands, 2004/'05: awareness of congenital rubella syndrome required]. / Rubella-epidemie in Nederland in 2004/'05: alertheid op congenitaal rubellasyndroom vereist.

Rubella is a public health problem due to the teratogenic effects associated with primary rubella infection during pregnancy (congenital rubella syndrome). Following universal rubella vaccination of infants in the Netherlands, the incidence of rubella has declined dramatically. However, since September 2004, an outbreak has occurred among unvaccinated individuals, most of whom declined vaccination based on religious beliefs. In the period 1 September 2004-22 March 2005, 166 cases of rubella were reported, including 12 pregnant women. Monitoring for signs that the epidemic has spread to other populations in the Netherlands is important because this might indicate the need for additional interventions. Awareness among health-care workers of the possible occurrence of congenital rubella syndrome should be raised. The clinical manifestations of congenital rubella syndrome are diverse, can be transient or permanent, and may not present until adolescence or adulthood. All cases of laboratory-confirmed rubella infection and congenital rubella syndrome should be reported to municipal health authorities. There is a possibility that this outbreak will spread abroad. The WHO aims to reduce the incidence of congenital rubella syndrome to < 1/100,000 live births. Health-care workers in the Netherlands should be extra alert to detect and notify rubella in a timely manner.