Author Correction: Rapid SARS-CoV-2 whole-genome sequencing and analysis for informed public health decision-making in the Netherlands.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Rapid SARS-CoV-2 whole-genome sequencing and analysis for informed public health decision-making in the Netherlands.

In late December 2019, a cluster of cases of pneumonia of unknown etiology were reported linked to a market in Wuhan, China1. The causative agent was identified as the species Severe acute respiratory syndrome-related coronavirus and was named SARS-CoV-2 (ref. 2). By 16 April the virus had spread to 185 different countries, infected over 2,000,000 people and resulted in over 130,000 deaths3. In the Netherlands, the first case of SARS-CoV-2 was notified on 27 February. The outbreak started with several different introductory events from Italy, Austria, Germany and France followed by local amplification in, and later also outside, the south of the Netherlands. The combination of near to real-time whole-genome sequence analysis and epidemiology resulted in reliable assessments of the extent of SARS-CoV-2 transmission in the community, facilitating early decision-making to control local transmission of SARS-CoV-2 in the Netherlands. We demonstrate how these data were generated and analyzed, and how SARS-CoV-2 whole-genome sequencing, in combination with epidemiological data, was used to inform public health decision-making in the Netherlands.

Current practices for respiratory syncytial virus surveillance across the EU/EEA Member States, 2017.

BackgroundRespiratory syncytial virus (RSV) is a major contributor to lower respiratory tract infections worldwide and several vaccine candidates are currently in development. Following vaccine introduction, reliable RSV surveillance should enable monitoring of vaccination impact. Data on the RSV disease burden in the European Union and European Economic Area (EU/EEA) are sparse.AimThe aim of this study was to gather knowledge on current practices of national RSV surveillance in the EU/EEA.MethodsNational Coordinators and National Focal Points for Influenza (epidemiologists and virologists) from the EU/EEA countries (n = 31) were invited to participate in an online survey in August and September 2017. The questionnaire covered questions on epidemiological and laboratory aspects of RSV surveillance.ResultsAll EU/EEA countries except Liechtenstein replied to the survey. Eighteen countries reported to have a sentinel surveillance system, 26 countries a non-sentinel surveillance system and three countries to have neither. RSV data collection was mostly done within the context of influenza surveillance. A wide range of diagnostic and characterisation assays was used for the detection of RSV.DiscussionThe majority of EU/EEA countries have some surveillance for RSV in place. The prevailing integration of RSV surveillance into the existing influenza sentinel surveillance system may lead to under-reporting of RSV. The documented variations in existing RSV surveillance systems and their outputs indicate that there is scope for developing guidelines on establishing comparable methods and outcomes for RSV surveillance across the EU/EEA, to ensure the availability of a consistent evidence base for assessing future vaccination programmes.

Successful Use of Advertisement Pictures to Assist Recall in a Food-Borne Hepatitis A Outbreak in The Netherlands, 2017.

This study describes an outbreak investigation of 14 hepatitis A cases in the Netherlands. The hepatitis A virus (HAV) genotype IB sequences in cases were highly similar (459/460 nt). The origin of strains could be narrowed to Bulgaria based on information from EPIS-FWD. As an association with consumption of soft fruit was suspected, a case-control study was initiated using a questionnaire and a list of pictures of soft fruit available at the supermarket chain involved. Twelve out of 13 cases consumed a specific frozen raspberry/blueberry product shown on the list (OR 46.0, 95% CI 5.0-27). In multivariable regression analysis this product was the only risk factor (aOR 26.6, 95% CI 2.0-263). Laboratory analyses could not demonstrate HAV-RNA in batches that had been on the market in the incubation period of patients. Trace back of frozen fruit showed that raspberries had been traded by a producer in Bulgaria. After withdrawal of the product from the supermarket no new cases were reported. Use of advertisement pictures of consumed food was helpful in this investigation. Suspicion of the source was strengthened by data from molecular typing and food trace back activities, underlining the importance of good (inter)national cooperation between public health and food safety organisations.

Positive experiences of volunteers working in deployable laboratories in West Africa during the Ebola outbreak.

The largest outbreak of Ebola virus disease ever started in West Africa in December 2013; it created a pressing need to expand the workforce dealing with it. The aim of this study was to gain insight into the experiences of volunteers from the European Union who worked in deployable laboratories in West Africa during the outbreak. This study is part of the EMERGE project. We assessed the experiences of 251 volunteers with a 19-item online questionnaire. The questions asked about positive aspects of volunteering such as learning new skills, establishing a new path in life, and changing life values. Other questionnaire subjects were the compliance to follow-up measures, the extent to which volunteers felt these measures restricted their daily activities, the fear of stigmatization, and worries about becoming infected or infecting their families. The volunteers reported positive effects that reached far beyond their daily work, such as changes in life priorities and a greater appreciation of the value of their own lives. Although the volunteers did not feel that temperature monitoring restricted their daily activities, full compliance to temperature monitoring and reporting it to the authorities was low. The volunteers did not fear Ebola infection for themselves or their families and were not afraid of stigmatization. With respect to the burden on the families, 50% reported that their family members were worried that the volunteer would be infected with Ebola virus. Altogether, the positive experiences of the volunteers in this study far outweigh the negative implications and constitute an important argument for inspiring people who intend to join such missions and for motivating the hesitant ones.

Knowledge, perceptions and media use of the Dutch general public and healthcare workers regarding Ebola, 2014.

BACKGROUND: The Ebola outbreak in West-Africa triggered risk communication activities to promote adequate preventive behaviour in the Netherlands. Our study investigated the level of knowledge, perceptions, and media use regarding Ebola. METHODS: In December 2014, an online questionnaire was administered to the Dutch population (n = 526) and Health Care Workers (HCW) (n = 760). RESULTS: The mean knowledge score (range 0-15) of HCW (m = 13.3;SD = 1.4) was significantly higher than the general public (m = 10.8;SD = 2.0). No significant difference was found in perceived severity and susceptibility. Perceived fear of the general public (m = 2.5; SD = 0.8) was significantly higher than among HCW (m = 2.4; SD = 0.7). Respondents primarily used television to obtain information. CONCLUSIONS: While Ebola was perceived severe, it did not lead to excessive fear or perceived susceptibility for developing the disease. Nonetheless, our research showed that knowledge with respect to human-to-human transmission is low, while this is crucial to complying with preventive measures. Our study reveals priorities for improving risk communication.

Cost of Nosocomial Outbreak Caused by NDM-1-Containing Klebsiella pneumoniae in the Netherlands, October 2015-January 2016.

During October-December 2015, 29 patients in a hospital in the Netherlands acquired nosocomial infection with a multidrug-resistant, New Delhi-metallo-ß-lactamase-positive Klebsiella pneumoniae strain. Extensive infection control measures were needed to stop this outbreak. The estimated economic impact of the outbreak was $804,263; highest costs were associated with hospital bed closures.

Follow-up of Contacts of Middle East Respiratory Syndrome Coronavirus-Infected Returning Travelers, the Netherlands, 2014.

Notification of 2 imported cases of infection with Middle East respiratory syndrome coronavirus in the Netherlands triggered comprehensive monitoring of contacts. Observed low rates of virus transmission and the psychological effect of contact monitoring indicate that thoughtful assessment of close contacts is prudent and must be guided by clinical and epidemiologic risk factors.

Effectiveness of human papillomavirus vaccine against incident and persistent infections among young girls: Results from a longitudinal Dutch cohort study.

INTRODUCTION: Because of the long interval between infection with high-risk human papillomavirus (hrHPV) and development of cervical cancer surrogate markers for cancer incidence are necessary to monitor vaccine effectiveness (VE). The aim of this study was to calculate VE of HPV16/18 vaccination by annually assessing incident and persistent infections among (un)vaccinated girls from the general Dutch population up to 3 years after vaccination. METHODS: In 2009, 1668 girls (54% vaccinated) aged 14-16 years were enrolled in a prospective cohort study. Annually, questionnaire data were obtained, and a vaginal swab was tested for type-specific HPV DNA with SPF10-LiPA. VE was estimated by a Poisson model comparing type-specific infection rates in (un)vaccinated girls. RESULTS: The adjusted VE (95% CI) was 73% (49-86%) against incident infections with HPV16/18 and 72% (52-84%) against HPV16/18/31/45. VE against persistent HPV16/18 was 100% and 76% (-17 to 95%) against HPV16/18/31/45. This number was lower (36%) when girls who were positive for HPV16 and 18 at baseline were included in the analysis. The overall VE for hrHPV types combined was small. Although 96% of girls were HPV-naïve at baseline, the cumulative 36-month incidence for any HPV was 20%, indicating high sexual activity. DISCUSSION: Vaccination is effective against incident and persistent infections with HPV16/18 and HPV16/18/31/45. Low VE against persistent HPV16/18 infection in girls positive at baseline indicates importance of vaccination before sexual debut.

Population- and type-specific clustering of multiple HPV types across diverse risk populations in the Netherlands.

In view of possible type replacement upon introduction of human papillomavirus (HPV) vaccination, we aimed to explore patterns of type-specific clustering across populations with various background infection risks. A total of 3,874 women from 3 cross-sectional studies in the Netherlands (in 2007-2009) provided vaginal self-samples, which were tested for 25 HPV genotypes by a sensitive molecular assay (SPF10 line probe assay, DDL Diagnostic Laboratory, Voorburg, the Netherlands). The number of concurrent HPV infections per woman was studied by Poisson regression. Associations between HPV types were investigated by generalized estimating equation analyses. The prevalence of any HPV type was 14% in a population-based study, 54% in a chlamydia screening intervention study, and 73% in a study among attendees of sexually transmitted infection clinics. Overall, multiple HPV infections were detected in 26% of the women. The number of concurrent HPV infections conformed to an overdispersed Poisson distribution, even after correction for known risk factors. Types differed significantly in their tendencies to be involved in coinfections, but no evidence for particular type-type interactions was found. Moreover, the strongest associations were observed in the lowest-risk population and vice versa.We found no indications of pairwise interactions, but our findings do suggest that clustering differs among HPV types and varies across risk groups.

Equity in human papilloma virus vaccination uptake?: sexual behaviour, knowledge and demographics in a cross-sectional study in (un)vaccinated girls in the Netherlands.

BACKGROUND: In the Netherlands, human papillomavirus (HPV) vaccination is part of a national program equally accessible for all girls invited for vaccination. To assess possible inequalities in vaccine uptake, we investigated differences between vaccinated and unvaccinated girls with regard to various characteristics, including education and ethnicity, (both associated with non-attendance to the national cervical screening program), sexual behaviour and knowledge of HPV. METHODS: In 2010, 19,939 nationwide randomly-selected 16-17 year-old girls (2009 vaccination campaign) were invited to fill out an online questionnaire. A knowledge scale score and multivariable analyses identified variables associated with vaccination status. RESULTS: 2989 (15%) of the selected girls participated (65% vaccinated, 35% unvaccinated). The participants were comparable with regard to education, ethnicity, most sexual risk behaviour and had similar knowledge scores on HPV transmission and vaccination. However, unvaccinated girls lived in more urbanised areas and were more likely to have a religious background. Irrespective of vaccination status, 81% of the girls were aware of the causal relationship between HPV and cervical cancer, but the awareness of the necessity of cervical screening despite being vaccinated was limited. CONCLUSIONS: HPV vaccine uptake was not associated with knowledge of HPV and with factors that are known to be associated with non-attendance to the cervical cancer screening program in the Netherlands. Furthermore, most sexual behaviour was not related to vaccination status meaning that teenage unvaccinated girls were not at a disproportionally higher risk of being exposed to HPV. Routine HPV vaccination may reduce the social inequity of prevention of cervical cancer.

Anal, penile, and oral high-risk HPV infections and HPV seropositivity in HIV-positive and HIV-negative men who have sex with men.

The effects of single or multiple concordant HPV infections at various anatomical sites on type-specific HPV seropositivity are currently unknown. In this cross-sectional study we assessed whether high-risk HPV infections at various anatomical sites (i.e., anal canal, penile shaft, and oral cavity), as well as concordant infections at multiple anatomical sites, were associated with type-specific seropositivity in HIV-positive and HIV-negative MSM. MSM aged ≥ 18 years were recruited in Amsterdam, the Netherlands (2010-2011). Baseline anal, penile, and oral samples were analyzed for HPV DNA and genotyped using a highly sensitive PCR and reverse line blot assay. Virus-like particle (VLP) based multiplex immunoassay was used to asses HPV-specific serum antibodies against L1 VLPs. The associations between HPV infections and type-specific seropositivity of seven high-risk HPV types (7-hrHPV: types 16, 18, 31, 33, 45, 52, 58) were estimated using logistic regression analyses with generalized estimating equations. We found that 86% of 306 HIV-positive MSM and 62% of 441 HIV-negative MSM were seropositive for at least one 7-hrHPV type. 69% of HIV-positive and 41% of HIV-negative MSM were infected with at least one 7-hrHPV type at the anus, penis, or oral cavity. In multivariable analyses, 7-hrHPV seropositivity was associated with type-specific anal (and not penile) 7-hrHPV infection, and did not significantly increase with a higher number of infected anatomical sites. Oral 7-hrHPV infection showed a positive, albeit non-significant, association with seropositivity. In conclusion, seropositivity among MSM appears to be largely associated with anal HPV infection, irrespective of additionally infected anatomical sites.

Characteristics of HPV-specific antibody responses induced by infection and vaccination: cross-reactivity, neutralizing activity, avidity and IgG subclasses.

OBJECTIVES: In order to assess HPV-specific IgG characteristics, we evaluated multiple aspects of the humoral antibody response that will provide insight in the HPV humoral immune response induced by HPV infection and vaccination. METHODS: Cross-reactivity of HPV-specific antibodies induced by infection or vaccination was assessed with VLP16 or 18 inhibition using a VLP-based multiplex immunoassay (MIA) for HPV16, 18, 31, 33, 45, 52 and 58. HPV16/18 specific IgG1-4 subclasses and avidity were determined with the VLP-MIA in sera after HPV infection and after vaccination. Neutralizing antibodies were determined in a small subset of single-seropositive and multi-seropositive naturally derived antibodies. RESULTS: Naturally derived antibodies from single-positive sera were highly genotype-specific as homologue VLP-inhibition percentages varied between 78-94%. In multi-positive sera, cross-reactive antibodies were observed both within and between α7 and α9 species. After vaccination, cross-reactive antibodies were mainly species-specific. Avidity of vaccine-derived HPV-specific antibodies was 3 times higher than that of antibodies induced by HPV infection (p<0.0001). IgG1 and IgG3 were found to be the predominant subclasses observed after HPV infection and vaccination. In the small subset tested, the number of single-positive sera with neutralizing capacity was higher than of multi-positive sera. CONCLUSION: Naturally derived HPV-specific antibodies from single-positive samples showed different characteristics in terms of cross-reactivity and neutralizing capacity compared with antibodies from multi-positive sera. Post-vaccination, HPV antibody avidity was approximately 3 times higher than antibody avidity induced by HPV infection. Therefore, antibody avidity might be a potential surrogate of protection.

Comparison of different assays to assess human papillomavirus (HPV) type 16- and 18-specific antibodies after HPV infection and vaccination.

We compared the measurement of human papillomavirus (HPV)-specific serum antibody levels with the virus-like-particle multiplex immunoassay (VLP-MIA), competitive Luminex immunoassay (cLIA), and glutathione S-transferase (GST) L1-based MIA. Using a large panel of serum samples, these assays showed mutually good correlations for both naturally induced and vaccine-derived HPV-specific antibody levels. However, an adaptation of the GST L1-based MIA resulted in an improved correlation with both cLIA and VLP-MIA.

Review: current knowledge on the role of HPV antibodies after natural infection and vaccination: implications for monitoring an HPV vaccination programme.

In 2006/2007, two vaccines were licensed against two of the most common HPV types that cause about 70% of cervical cancers. Clinical trials show that vaccinated individuals develop high levels of neutralizing antibodies. Although these data suggest that serum antibodies are the mode of action against HPV infection, it is uncertain whether immune responses generated by vaccination are similar to those induced by a natural infection. In this review, the current knowledge of humoral immune responses after natural infection and vaccination is described. Serosurveillance can be used as a monitoring tool to study vaccine uptake, the impact of HPV16/18 vaccination on other HPV types, dynamics of HPV infection and herd-immunity. In addition, factors that contribute to a higher seroresponse after a natural infection, which are summarized in this article (a persistent DNA infection, increased viral load, immunosuppression and high sexual risk behavior), can help to interpret these indirect effects better.

Detection of systemic and mucosal HPV-specific IgG and IgA antibodies in adolescent girls one and two years after HPV vaccination.

The bivalent HPV16/18 vaccine induces high antibody concentrations in serum while data about antibody responses in the cervix are limited. In this study, we investigated pre- and post-vaccination antibody responses against seven high-risk HPV types by detection of IgG and IgA HPV-specific antibodies in cervical secretion samples (CVS) and serum. From an HPV vaccine monitoring study CVS and serum samples were available (pre-vaccination (n = 297), one year (n = 211) and two years (n = 141) post-dose-one vaccination) from girls aged 14-16 y. The girls were vaccinated with the bivalent HPV vaccine at months 0, 1 and 6. CVS was self-sampled using a tampon. Samples were tested for HPV-specific antibodies (HPV16/18/31/33/45/52/58) by a VLP-based multiplex immunoassay. Post-vaccination, IgG and IgA antibody levels for HPV16/18 were detectable in CVS and amounted to 2% and 1% of the IgG and IgA antibody levels observed in serum, respectively. The antibody levels remained constant between one and two years after vaccination. The correlation between CVS and serum was similar for IgG and IgA vaccine-derived antibody levels for HPV16 (rs = 0.58, rs = 0.54) and HPV18 (rs = 0.50, rs = 0.55). Vaccine-derived IgG antibody levels against cross-reactive HPV types in CVS and in serum were highest for HPV45. No IgA cross-reactive antibody responses could be detected in CVS. Post-vaccination, HPV16/18 IgG and IgA antibodies are not only detectable in serum but also in CVS. The correlation of HPV16/18 IgG antibody levels between serum and CVS suggests that vaccine induced HPV antibodies transudate and/or exudate from the systemic circulation to the cervical mucosa to provide protection against HPV infections.

Changes in antibody seroprevalence of seven high-risk HPV types between nationwide surveillance studies from 1995-96 and 2006-07 in The Netherlands.

OBJECTIVE: This study evaluates trends in antibody seroprevalences of seven high-risk human papillomavirus (hr-HPV) serotypes (HPV16, 18, 31, 33, 45, 52, and 58) between the 1995-96 and 2006-07 sero-surveys among the Dutch general population in the pre-vaccination era. METHODS: Serum samples of men and women (0-79 years of age) from two cross-sectional population-based serosurveillance studies performed in 1995-96 (n = 3303) and 2006-07 (n = 6384) were tested for HPV-specific antibodies in a VLP-based multiplex immunoassay. RESULTS: HPV16-specific antibody seroprevalence increased during adolescence and shifted to younger ages in the 2006-07 survey compared to the 1995-96 survey. This step-up in HPV16 seroprevalence was most pronounced in women, while a more gradual increase was observed in men. Also in cohorts older than 49 years, HPV16 seroprevalence was higher in 2006-07 as compared to 1995-96 survey. A higher overall seroprevalence in individuals older than 15 years of age was found for HPV16, 18, 31 and 45 in 2006-07 as compared to 1995-96. For HPV33, 52 and 58 seroprevalences were comparable over this 11-year time period. Seropositivity for one or more HPV types was significantly higher in 2006-07 (23.1%) than in 1995-96 (20.0%) (p = 0.013). Multi-seropositivity increased from 7.1% in 1995-96 up to 10.2% in 2006-07 (p<0.0001). Differences in HPV seropositivity for at least one of the seven HPV types between both surveys could be explained in addition to demographic characteristics (age, sex, urbanization degree and ethnicity), also by changes in sexual behaviour (marital status, age of sexual debut and ever reported an STI). CONCLUSION: The observed increase in particular HPV16 seroprevalence could be due to changes in sexual behaviour over the years, and especially in age of sexual debut. Seroprevalence studies provide insight into the distribution of HPV types and infection dynamics in the general population over time, which is important to assess the impact of HPV-vaccination.

Seroprevalence of seven high-risk HPV types in The Netherlands.

BACKGROUND: To obtain insight into the age-specific seroprevalence for seven high-risk human papillomavirus (hr-HPV) serotypes (HPV16, 18, 31, 33, 45, 52, and 58) among the general population in the pre-vaccination era in The Netherlands. METHODS: From a cross-sectional population-based study (ISRCTN 20164309) performed in 2006/2007 6384 sera of men, women and children were tested for seven hr-HPV specific antibodies using a fluorescent bead-based multiplex immunoassay with virus-like particles of the seven HPV serotypes. RESULTS: An increase in seroprevalence was observed in adolescents, especially for the most prevalent HPV type 16 (up to 11.3%). The increase was most pronounced in women, but was less clear for the other six HPV serotypes. Relatively stable seroprevalences were found in the middle aged cohorts and a slight decrease in the elderly. For the age cohorts >14 years, the seroprevalence among women (25.2%) was higher compared with men (20.3%) (p=0.0002). We found that 10.1% of the population was seropositive for multiple HPV serotypes. CONCLUSIONS: The HPV vaccination program is targeted at preadolescents as is justified by the results in this study in which a step-up in HPV seroprevalence is observed at ages of sexual debut. Although direct interpretation of seroprevalence data are hampered by cross-reactivity and seroconversion rate, these data are useful as baseline to evaluate long-term population effects of the HPV16/18 vaccination program.