Epidemiologic and Genomic Analysis of SARS-CoV-2 Delta Variant Superspreading Event in Nightclub, the Netherlands, June 2021.

We report a severe acute respiratory syndrome coronavirus 2 superspreading event in the Netherlands after distancing rules were lifted in nightclubs, despite requiring a negative test or vaccination. This occurrence illustrates the potential for rapid dissemination of variants in largely unvaccinated populations under such conditions. We detected subsequent community transmission of this strain.

Hepatitis C Virus Transmission Among Men Who Have Sex With Men in Amsterdam: External Introductions May Complicate Microelimination Efforts.

BACKGROUND: It is unclear whether unrestricted access and high uptake of direct-acting antivirals (DAAs) is sufficient to eliminate hepatitis C virus (HCV) in high-risk populations such as men who have sex with men (MSM). This study presents historic trends and current dynamics of HCV transmission among MSM in Amsterdam based on sequence data collected between 1994 and 2019. METHODS: Hypervariable region 1 sequences of 232 primary HCV infections and 56 reinfections were obtained from 244 MSM in care in Amsterdam. Maximum-likelihood phylogenies were constructed for HCV genotypes separately, and time-scaled phylogenies were constructed using a Bayesian coalescent approach. Transmission clusters were determined by Phydelity and trends in the proportion of unclustered sequences over time were evaluated using logistic regression. RESULTS: Seventy-six percent (218/288) of sequences were part of 21 transmission clusters and 13 transmission pairs. Transmission cluster sizes ranged from 3 to 44 sequences. Most clusters were introduced between the late 1990s and early 2010s and no new clusters were introduced after 2012. The proportion of unclustered sequences of subtype 1a, the most prevalent subtype in this population, fluctuated between 0% and 20% in 2009-2012, after which an increase occurred from 0% in 2012 to 50% in 2018. CONCLUSIONS: The proportion of external introductions of HCV infections among MSM in Amsterdam has recently increased, coinciding with high DAA uptake. Frequent international transmission events will likely complicate local microelimination efforts. Therefore, international collaboration combined with international scale-up of prevention, testing, and treatment of HCV infections (including reinfections) is warranted, in particular for local microelimination efforts.

High incidence of HCV in HIV-negative men who have sex with men using pre-exposure prophylaxis.

BACKGROUND & AIMS: HCV has emerged as a sexually transmitted infection (STI) among HIV-positive men who have sex with men (MSM). We evaluated HCV incidence and its risk factors among HIV-negative MSM using HIV pre-exposure prophylaxis (PrEP). METHODS: Participants of the Amsterdam PrEP project were tested for HCV antibodies or HCV-RNA every 6 months. Participants used daily or event-driven PrEP and could switch regimens during follow-up. We calculated incidence rates (IRs) for overall HCV infection and separately for primary and re-infection. A univariable Bayesian exponential survival model was used to identify risk factors associated with incident HCV infection. The HCV NS5B gene fragment (709 bp) was sequenced and compared to HCV isolates from HIV-positive MSM and other risk groups (n = 419) using phylogenetic analysis. RESULTS: Among 350 participants contributing 653.6 person-years (PYs), we detected 15 HCV infections in 14 participants (IR = 2.30/100PY). There were 8 primary infections (IR = 1.27/100PY) and 7 re-infections (IR = 27.8/100PY). IR was 2.71/100PY in daily and 1.15/100PY in event-driven PrEP users. Factors associated with incident HCV infection were higher number of receptive condomless anal sex acts with casual partners (posterior hazard ratio [HR] 1.57 per ln increase; 95% credibility interval [CrI] 1.09-2.20), anal STI (posterior HR 2.93; 95% CrI 1.24-7.13), injecting drug use (posterior HR 4.69; 95% CrI 1.61-12.09) and sharing straws when snorting drugs (posterior HR 2.62; 95% CrI 1.09-6.02). We identified robust MSM-specific HCV clusters of subtypes 1a, 4d, 2b and 3a, which included MSM with and without HIV. CONCLUSIONS: HIV-negative MSM using PrEP are at risk of incident HCV infection, while identified risk factors are similar to those in HIV-positive MSM. Regular HCV testing is needed, especially for those with a previous HCV infection and those reporting risk factors. LAY SUMMARY: We report that hepatitis C virus infections are frequently acquired among HIV-negative men who have sex with men (MSM) using pre-exposure prophylaxis to prevent HIV infection. New infections occurred more frequently in those reporting receptive anal sex without using condoms, having an anal sexually transmitted infection, injecting drugs, and sharing straws when snorting drugs. The viruses found in HIV-negative men using pre-exposure prophylaxis are genetically similar to those in HIV-positive men, but not in other hepatitis C risk groups, suggesting that (sexual) transmission is occurring between HIV-positive MSM and HIV-negative MSM using pre-exposure prophylaxis. CLINICAL TRIAL NUMBER: Dutch trial registration number NTR5411.

Ultrastructural aspects of foreign body giant cells generated on different substrates.

Implantation of biomaterials into the body, e.g. for tissue engineering purposes, induces a material-dependent inflammatory response called the foreign body reaction (FBR). A hallmark feature of this response is the formation of large multinucleated cells: foreign body giant cells (FBGCs). Biomaterials like cross-linked and non-cross-linked collagen often induce the formation of FBGCs. It is unknown whether different biomaterials result in the formation of different FBGCs. To investigate this, we implanted cross-linked and non-cross-linked dermal sheep collagen subcutaneously in mice. After 21 days the implanted material was collected and prepared for ultrastructural analysis. More FBGCs formed on and between implants of cross-linked collagen compared to non-cross-linked material. The ultrastructural aspects of the FBGCs present on the two types of implants proved to be similar. On both materials, they formed long slender protrusions on the basolateral membrane, they were very rich in mitochondria, contained numerous nuclei, and showed signs of the presence of a clear zone facing the implanted material. Similar clear zones, that resemble osteoclastic features, were also seen in FBGCs generated in vitro on bone slices, but these cells did not form a ruffled border. However, similarities in ultrastructure such as the occurrence of slender protrusions and high mitochondrion content were also found in the FBGCs generated in vitro. These data indicate that FBGCs formed on different substrates share many morphological characteristics. The formation of long finger-like protrusions seemed typical for the FBGCs, in vivo as well as in vitro, however the function of these structures needs further analysis.

Hepatitis C virus transmission between eight high-income countries among men who have sex with men: a whole-genome analysis.

BACKGROUND: Microelimination of the hepatitis C virus (HCV) among men who have sex with men (MSM) could be complicated by continuous external introductions and the emergence of phylogenetic clusters harbouring clinically significant resistance-associated substitutions (RAS). To investigate international clustering and the prevalence and transmission of RAS, we aimed to analyse whole-genome HCV sequences from MSM with a recently acquired infection who participated in a large, international HCV treatment trial. METHODS: For this whole-genome analysis, we obtained HCV sequences from 128 MSM who had acquired HCV within the past 12 months and were participating in the REACT trial. The participants from whom sequences were obtained were recruited at 24 sites in eight countries. We inferred maximum-likelihood phylogenies and identified transmission clusters for HCV genotypes separately. We constructed time-scaled phylogenies to estimate cluster introduction dates and used a Bayesian Skygrid approach to estimate the effective population size over the past 50 years. We calculated the prevalence of RAS and the extent of RAS transmission in the study population. FINDINGS: The majority of recent HCV infections were part of international networks that arose in the late 1990s and early 2000s. Sequences obtained in the same country clustered frequently, and in 36% of subclusters since 2015 we found evidence of international transmission. European MSM were more likely than non-European MSM to be in a cluster (odds ratio 11·9 [95% CI 3·6-43·4], p<0·0001). The effective population size decreased rapidly since around 2015 in Europe. RAS associated with substantially diminished cure rates were infrequently detected and transmission of highly resistant viruses was not observed. INTERPRETATION: Despite antiviral treatment becoming widely available, international transmission of HCV among MSM has still occurred over the past 8 years, which could complicate microelimination of the virus in this population. RAS-enriched clusters and widespread RAS transmission are currently not a threat to elimination goals. These findings support an international approach for HCV microelimination among MSM. FUNDING: National Institutes of Health and Dr. C.J. Vaillant Fonds.

Regional importation and asymmetric within-country spread of SARS-CoV-2 variants of concern in the Netherlands.

Background: Variants of concern (VOCs) of SARS-CoV-2 have caused resurging waves of infections worldwide. In the Netherlands, the Alpha, Beta, Gamma, and Delta VOCs circulated widely between September 2020 and August 2021. We sought to elucidate how various control measures, including targeted flight restrictions, had impacted the introduction and spread of these VOCs in the Netherlands. Methods: We performed phylogenetic analyses on 39,844 SARS-CoV-2 genomes collected under the Dutch national surveillance program. Results: We found that all four VOCs were introduced before targeted flight restrictions were imposed on countries where the VOCs first emerged. Importantly, foreign introductions, predominantly from other European countries, continued during these restrictions. After their respective introductions into the Netherlands, the Alpha and Delta VOCs largely circulated within more populous regions of the country with international connections before asymmetric bidirectional transmissions occurred with the rest of the country and the VOC became the dominant circulating lineage. Conclusions: Our findings show that flight restrictions had limited effectiveness in deterring VOC introductions due to the strength of regional land travel importation risks. As countries consider scaling down SARS-CoV-2 surveillance efforts in the post-crisis phase of the pandemic, our results highlight that robust surveillance in regions of early spread is important for providing timely information for variant detection and outbreak control. Funding: None.

Regional importation and asymmetric within-country spread of SARS-CoV-2 variants of concern in the Netherlands.

Variants of concern (VOCs) of SARS-CoV-2 have caused resurging waves of infections worldwide. In the Netherlands, Alpha, Beta, Gamma and Delta variants circulated widely between September 2020 and August 2021. To understand how various control measures had impacted the spread of these VOCs, we analyzed 39,844 SARS-CoV-2 genomes collected under the Dutch national surveillance program. We found that all four VOCs were introduced before targeted flight restrictions were imposed on countries where the VOCs first emerged. Importantly, foreign introductions, predominantly from other European countries, continued during these restrictions. Our findings show that flight restrictions had limited effectiveness in deterring VOC introductions due to the strength of regional land travel importation risks. We also found that the Alpha and Delta variants largely circulated more populous regions with international connections after their respective introduction before asymmetric bidirectional transmissions occurred with the rest of the country and the variant dominated infections in the Netherlands. As countries consider scaling down SARS-CoV-2 surveillance efforts in the post-crisis phase of the pandemic, our results highlight that robust surveillance in regions of early spread is important for providing timely information for variant detection and outbreak control.

Induction of cross-neutralizing antibodies by a permuted hepatitis C virus glycoprotein nanoparticle vaccine candidate.

Hepatitis C virus (HCV) infection affects approximately 58 million people and causes ~300,000 deaths yearly. The only target for HCV neutralizing antibodies is the highly sequence diverse E1E2 glycoprotein. Eliciting broadly neutralizing antibodies that recognize conserved cross-neutralizing epitopes is important for an effective HCV vaccine. However, most recombinant HCV glycoprotein vaccines, which usually include only E2, induce only weak neutralizing antibody responses. Here, we describe recombinant soluble E1E2 immunogens that were generated by permutation of the E1 and E2 subunits. We displayed the E2E1 immunogens on two-component nanoparticles and these nanoparticles induce significantly more potent neutralizing antibody responses than E2. Next, we generated mosaic nanoparticles co-displaying six different E2E1 immunogens. These mosaic E2E1 nanoparticles elicit significantly improved neutralization compared to monovalent E2E1 nanoparticles. These results provide a roadmap for the generation of an HCV vaccine that induces potent and broad neutralization.

Rapid reinfection with SARS-CoV-2 variant-of-concern Alpha detected in a nurse during an outbreak at a non-covid inpatient ward: lessons learned.

We describe the lessons learned during a SARS-CoV-2 variant-of-concern Alpha outbreak investigation at a normal care unit in a university hospital in Amsterdam in December 2020. The outbreak consisted of nine nurses and two roomed-in patient family members. (attack rate 18%). One nurse tested positive with a phylogenetically distinct variant, after a documented infection 83 days prior. Three key points were taken from this investigation. First, it was controlled by adherence to existing guidelines, despite increased transmissibility of the variant. Second, viral sequencing can inform transmission cluster inference, but the epidemiological context is essential to draw appropriate conclusions. Third, reinfections with Alpha variants can occur rapidly after primary infection.

Serologic Surveillance and Phylogenetic Analysis of SARS-CoV-2 Infection Among Hospital Health Care Workers.

Importance: It is unclear when, where, and by whom health care workers (HCWs) working in hospitals are infected with SARS-CoV-2. Objective: To determine how often and in what manner nosocomial SARS-CoV-2 infection occurs in HCW groups with varying exposure to patients with COVID-19. Design, Setting, and Participants: This cohort study comprised 4 weekly measurements of SARS-CoV-2-specific antibodies and collection of questionnaires from March 23 to June 25, 2020, combined with phylogenetic and epidemiologic transmission analyses at 2 university hospitals in the Netherlands. Included individuals were HCWs working in patient care for those with COVID-19, HCWs working in patient care for those without COVID-19, and HCWs not working in patient care. Data were analyzed from August through December 2020. Exposures: Varying work-related exposure to patients infected with SARS-CoV-2. Main Outcomes and Measures: The cumulative incidence of and time to SARS-CoV-2 infection, defined as the presence of SARS-CoV-2-specific antibodies in blood samples, were measured. Results: Among 801 HCWs, there were 439 HCWs working in patient care for those with COVID-19, 164 HCWs working in patient care for those without COVID-19, and 198 HCWs not working in patient care. There were 580 (72.4%) women, and the median (interquartile range) age was 36 (29-50) years. The incidence of SARS-CoV-2 was increased among HCWs working in patient care for those with COVID-19 (54 HCWs [13.2%; 95% CI, 9.9%-16.4%]) compared with HCWs working in patient care for those without COVID-19 (11 HCWs [6.7%; 95% CI, 2.8%-10.5%]; hazard ratio [HR], 2.25; 95% CI, 1.17-4.30) and HCWs not working in patient care (7 HCWs [3.6%; 95% CI, 0.9%-6.1%]; HR, 3.92; 95% CI, 1.79-8.62). Among HCWs caring for patients with COVID-19, SARS-CoV-2 cumulative incidence was increased among HCWs working on COVID-19 wards (32 of 134 HCWs [25.7%; 95% CI, 17.6%-33.1%]) compared with HCWs working on intensive care units (13 of 186 HCWs [7.1%; 95% CI, 3.3%-10.7%]; HR, 3.64; 95% CI, 1.91-6.94), and HCWs working in emergency departments (7 of 102 HCWs [8.0%; 95% CI, 2.5%-13.1%]; HR, 3.29; 95% CI, 1.52-7.14). Epidemiologic data combined with phylogenetic analyses on COVID-19 wards identified 3 potential HCW-to-HCW transmission clusters. No patient-to-HCW transmission clusters could be identified in transmission analyses. Conclusions and Relevance: This study found that HCWs working on COVID-19 wards were at increased risk for nosocomial SARS-CoV-2 infection with an important role for HCW-to-HCW transmission. These findings suggest that infection among HCWs deserves more consideration in infection prevention practice.

Sexually transmitted hepatitis C virus infections: current trends, and recent advances in understanding the spread in men who have sex with men.

INTRODUCTION: Hepatitis C virus (HCV) is a major public health threat. Although the recent availability of highly effective directly acting antivirals created optimism towards HCV elimination, there is ongoing transmission of HCV in men who have sex with men (MSM). We here report current epidemiological trends and synthesise evidence on behavioural, network, cellular and molecular host factors associated with sexual transmission of HCV, in particular the role of HIV-1 co-infection. We discuss prevention opportunities focusing on the potential of HCV treatment. METHODS: We searched MEDLINE, fact sheets from health professional bodies and conference abstracts using appropriate keywords to identify and select relevant reports. RESULTS AND DISCUSSION: Recent studies strongly suggest that HCV is transmitted via sexual contact in HIV-positive MSM and more recently in HIV-negative MSM eligible for or on pre-exposure prophylaxis. The reinfection risk following clearance is about 10 times the risk of primary infection. International connectedness of MSM transmission networks might contribute to ongoing reinfection. Some of these networks might overlap with networks of people who inject drugs. Although, the precise mechanisms facilitating sexual transmission remain unclear, damage to the mucosal barrier in the rectum could increase susceptibility. Mucosal dendritic cell subsets could increase HCV susceptibility by retaining HCV and transmitting the virus to other cells, allowing egress into blood and liver. Early identification of new HCV infections is important to prevent onward transmission, but early diagnosis of acute HCV infection and prompt treatment is hampered by the slow rate of HCV antibody seroconversion, which in rare cases may take more than a year. Novel tests such as testing for HCV core antigen might facilitate early diagnosis. CONCLUSIONS: High-risk sexual behaviour, network characteristics, co-infection with sexually transmitted infections like HIV-1 and other concomitant bacterial and viral sexually transmitted infections are important factors that lead to HCV spread. Targeted and combined prevention efforts including effective behavioural interventions and scale-up of HCV testing and treatment are required to halt HCV transmission in MSM.

Cost-effectiveness of screening for chronic hepatitis B and C among migrant populations in a low endemic country.

BACKGROUND: Chronic infection with hepatitis B or C virus (HBV/HCV) can progress to cirrhosis, liver cancer, and even death. In a low endemic country as the Netherlands, migrants are a key risk group and could benefit from early diagnosis and antiviral treatment. We assessed the cost-effectiveness of screening foreign-born migrants for chronic HBV and/or HCV using a societal perspective. METHODS: The cost-effectiveness was evaluated using a Markov model. Estimates on prevalence, screening programme costs, participation and treatment uptake, transition probabilities, healthcare costs, productivity losses and utilities were derived from the literature. The cost per Quality Adjusted Life Year (QALY) gained was estimated and sensitivity analyses were performed. RESULTS: For most migrant groups with an expected high number of chronically infected cases in the Netherlands combined screening is cost-effective, with incremental cost-effectiveness ratios (ICERs) ranging from €4,962/QALY gained for migrants originating from the Former Soviet Union and Vietnam to €9,375/QALY gained for Polish migrants. HBV and HCV screening proved to be cost-effective for migrants from countries with chronic HBV or HCV prevalence of ≥0.41% and ≥0.22%, with ICERs below the Dutch cost-effectiveness reference value of €20,000/QALY gained. Sensitivity analysis showed that treatment costs influenced the ICER for both infections. CONCLUSIONS: For most migrant populations in a low-endemic country offering combined HBV and HCV screening is cost-effective. Implementation of targeted HBV and HCV screening programmes to increase early diagnosis and treatment is important to reduce the burden of chronic hepatitis B and C among migrants.