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- COVID-19 vaccination and antibody response in healthcare workers: a longitudinal serological study following the 2023-2024 COVID-19 vaccination campaignPublication . Almeida Santos, João; Henriques, Camila; Amaral, Palmira; Guiomar, Raquel; Machado, Ausenda; Gaio, VâniaBackground: Healthcare workers (HCWs) are essential frontline responders to public health emergencies and are one of the risk groups targeted by annual vaccination campaigns. Serological studies are valuable for high-risk groups such as HCWs, as they contribute to assess vulnerability, monitor infection control measures, and guide vaccination strategies in high-risk settings. This study aimed to assess humoral response at baseline, 3 and 6 months after the 2023–2024 COVID-19 vaccination campaign in HCWs, and to identify demographic and clinical factors associated with variations in antibody levels over time. Methods: Prospective cohort study of vaccinated HCWs at a central hospital in Portugal (September 2023–May 2024). Serial serological tests to assess anti-spike receptor-binding domain (anti-RBD/S) and anti-nucleocapsid protein (anti-N) IgG antibodies were used to monitor the immune response and SARS-CoV-2 infection history, respectively. Wilcoxon signed-rank tests were used to assess changes in antibody levels over time, and linear regression models were used to identify factors associated with variations in SARS-CoV-2 anti-RBD/S IgG concentrations, on the basis of available demographic and clinical data. Results: In a cohort of 166 HCWs who received the 2023–2024 COVID-19 booster vaccine, anti-RBD/S IgG antibody levels significantly increased at 3 months post-vaccination (16 007.4 vs. 30 572.9 AU/mL) before declining by 6 months (18 327.3 AU/mL), nearing baseline levels. Previous infection (β = 1.92, 95% CI: 1.33-2.77) and older age (β = 2.65, 95%CI: 1.64‐4.29) were associated with higher antibody concentrations at baseline, whereas smoking was linked to lower antibody levels at 6 months (β = 0.32, 95%CI: 0.11–0.88). Other factors, such as sex and chronic conditions, had no consistent significant impact over time. Conclusions: Although SARS-CoV-2 anti-RBD/S IgG antibody concentrations declined significantly six months after the 2023–2024 COVID-19 booster vaccination, they remained at relatively high concentrations over the follow-up period. This study provides new insight into these dynamics in a highly vaccinated and exposed HCWs cohort during a later post-pandemic phase, highlighting the influence of prior infection, age, and smoking on antibody persistence and reinforces the relevance of ongoing immune monitoring of this risk group to guide tailored control strategies. However, vaccine effectiveness studies in highly exposed and vaccinated populations, such as HCWs, are needed to better inform the role of antibody monitoring in this context, especially given the ongoing trend of annually updated vaccines.
- COVID-19 Vaccine Effectiveness Against Hospitalization in Older Adults, VEBIS Hospital Network, Europe, September 2024-May 2025Publication . Rojas-Castro, Madelyn; Verdasca, Nuno; Monge, Susana; De Mot, Laurane; Trobajo-Sanmartín, Camino; Duffy, Róisín; Túri, Gergő; Kuliese, Monika; Duerrwald, Ralf; Borg, Maria-Louise; Popovici, Odette; Gomez, Verónica; Makarić, Zvjezdana Lovrić; Launay, Odile; Marques, Diogo F.P.; Pozo, Francisco; Witdouck, Arne; Martínez-Baz, Iván; Fitzgerald, Margaret; Oroszi, Beatrix; Jančorienė, Ligita; Buda, Silke; Dziugyte, Ausra; Lazăr, Mihaela; Machado, Ausenda; Tabain, Irena; Nguyen, Liem Binh Luong; Wagner, Eva Rivas; Dufrasne, François; Castilla, Jesús; Domegan, Lisa; Velkey, Viktória; Majauskaite, Fausta; Hackmann, Carolin; Nicolay, Nathalie; Bacci, Sabrina; Rose, Angela M.C.; European Hospital Vaccine Effectiveness GroupWe estimated COVID-19 vaccine effectiveness (VE) against PCR-confirmed SARS-CoV-2 hospitalization in patients ≥ 60 years with severe acute respiratory infection, using a multicenter, test-negative, case-control study across seven sites in six European countries between September 2024 and May 2025. We included 352 cases (115 vaccinated; 33%) and 9980 controls (5024 vaccinated; 50%). VE was 42% (95% CI: 15; 61) 14-59 days post-vaccination, 32% (95% CI: -1; 54) at 60-119 days, and 36% (95% CI: 2; 60) at 120-179 days, and no effect thereafter. Among adults aged 60-79 and ≥ 80 years, we observed moderate VE against COVID-19 hospitalization for up to 2 and 4 months, respectively.
- Detection of Echinococcus spp. and other taeniid species in lettuces and berries: Two international multicenter studies from the MEmE projectPublication . Umhang, Gérald; Bastien, Fanny; Cartet, Alexandra; Ahmad, Haroon; van der Ark, Kees; Berg, Rebecca; Bonelli, Piero; Davidson, Rebecca K.; Deplazes, Peter; Deksne, Gunita; Gargate, Maria João; Van der Giessen, Joke; Jamil, Naila; Jokelainen, Pikka; Karamon, Jacek; M'Rad, Selim; Maksimov, Pavlo; Oudni-M'Rad, Myriam; Muchaamba, Gillian; Oksanen, Antti; Pepe, Paola; Poulle, Marie-Lazarine; Rinaldi, Laura; Samorek-Pieróg, Małgorzata; Santolamazza, Federica; Santoro, Azzurra; Santucciu, Cinzia; Saarma, Urmas; Schnyder, Manuela; Villena, Isabelle; Wassermann, Marion; Casulli, Adriano; Boué, FranckCystic and alveolar echinococcosis are severe zoonotic diseases characterized by long asymptomatic periods lasting months or years. Viable Echinococcus spp. eggs released into the environment through the feces of canids can infect humans through accidental ingestion via hand-to-mouth contact or consumption of contaminated food or water. Both Echinococcus multilocularis and Echinococcus granulosus sensu lato are considered as foodborne parasites. However, when considering possible pathways of human infection, it appears that food and water-borne related variables do not significantly increase the risk of infection. Providing evidence-based data for the presence of DNA and, potentially, eggs in fresh produce is crucial in understanding foodborne transmission of Echinococcus spp. to humans. Two multicenter and multicountry studies were conducted within the One Health EJP framework to estimate the proportion of lettuces and berries contaminated by E. multilocularis, E. granulosus sensu lato, and other taeniid DNAs from a total of 12 European countries, Tunisia and Pakistan. A total of 1117 lettuces, 71 others vegetables, 300 strawberries, 130 blueberries and 50 others berries samples were collected and analysed by washing, sequential sieving and real-time PCRs. E. multilocularis DNA was detected in 1.2 % (7/570) of lettuce samples tested from the seven European endemic countries (Denmark, France, Germany, Latvia, the Netherlands, Poland and Switzerland) and in 2 % (2/100) from Pakistan. E. granulosus sensu lato DNA was identified in 1.3 % of lettuces (9/695) collected in five European endemic countries (France, Italy, Latvia, Poland and Portugal) and in 12 % (9/75) and 4 % (4/100) from Tunisia and Pakistan, respectively. All E. granulosus sensu lato samples were identified as E. granulosus sensu stricto (20/22), except for two identified as E. canadensis (2/22) from Latvia and Pakistan. Regarding berries, E. multilocularis DNA was detected in 5.4 % (n = 11/202) of strawberries, 7.3 % (6/82) of blueberries from the seven European endemic countries and 56 % (14/25) of blueberries from Pakistan. High contamination rates of E. granulosus sensu stricto were found outside of Europe, with 12.0 % (3/25) in blueberries from Pakistan and 81.3 %. (13/16) in strawberries from Tunisia. The total contamination rate of all taeniid species DNA in lettuces (5.3 %; 59/1117), others vegetables (5.6 %; 4/71) and berries (12.1 %; 58/480) suggests that the transfer of taeniid eggs from carnivore feces to food is not uncommon. Although we assume that eggs are the source of the DNA detected in this study, the viability of such eggs is unknown. The detection of Echinococcus species in lettuces and berries suggests a potential risk of foodborne human infection. The relative contribution of this risk remains to be estimated. Further studies on food and environmental contamination are necessary to cover different epidemiological contexts and social habits, leading to a better understanding of human infections by Echinococcus spp. eggs.
- Genomic diversity of Enterobacteriaceae on food-processing surfaces: an overlooked non-clinical setting with public health implicationsPublication . Peixoto, Andreia; Nova, Lúcia; Mourão, Joana; Matos, Cátia; Santos, Susana; Rodrigues, João; Saraiva, Margarida; Correia, Cristina Belo; Batista, Rita; Peixe, Luísa; Novais, Carla; Antunes, PatríciaBacterial hazards on contaminated surfaces in food-processing environments pose significant food safety risks. Hygiene monitoring of surfaces in direct or indirect contact with food typically relies on a limited set of bacterial indicators, such as Enterobacteriaceae counts. However, their genomic diversity remains poorly characterised. The aim of this study was to provide a comprehensive genomic characterisation of Enterobacteriaceae recovered from food-contact surfaces after cleaning and disinfection with biocides in foodservice units. Diverse strains were identified, with some STs shared across samples and/or foodservices. - A diverse Enterobacteriaceae population persists on food-contact surfaces even after cleaning and disinfection with biocides, with evidence of cross-contamination. - These surfaces represent critical points of contact for strains that are genetically similar to those circulating in food, environment, and human clinical sources, including strains carrying clinically relevant AMR genes. - Further research is needed to understand the factors driving their persistence and dissemination in foodservice environments, aiming to enhance food safety risk management protocols and protect public health.
- Genomic evolution and re-emergence of a multidrug-resistant Clostridioides difficile RT027 clone with reduced vancomycin susceptibility driving a prolonged hospital outbreakPublication . Isidro, Joana; Dionísio, Filipa; Alves, Frederico; Almeida, Soraia; Santos, Cláudia; Santos, Manuel Mota; Reis, Ernestina; Oliveira, Júlio R.; Gomes, João Paulo; Oleastro, MónicaFollowing an extended period of declining prevalence of the epidemic Clostridioides difficile ribotype 027 (RT027) in Portugal, a genetically distinct, multidrug-resistant (MDR) RT027 strain with reduced susceptibility to vancomycin has emerged, causing a 15-month outbreak. This investigation provides epidemiological and genomic evidence for renewed circulation and evolutionary adaptation of this high-risk lineage. A comprehensive outbreak investigation was conducted in a tertiary-care hospital in northern Portugal between 2023 and 2025. Epidemiological and clinical data, antimicrobial exposures, and infection-control measures were analysed. Whole-genome sequencing (WGS) was performed to characterize the outbreak clone. Sixty-six RT027 C. difficile infection (CDI) cases were confirmed, with incidence peaking at 5.46 cases per 10,000 patient-bed days in April 2024. WGS revealed an unusual accumulation of AMR determinants conferring a broad MDR phenotype. Notably, all isolates harboured the VanR T115A substitution, a rare mutation previously linked to reduced vancomycin susceptibility, raising concerns regarding evolving antimicrobial tolerance within RT027. The close relatedness to 2016-2018 USA isolates suggests a recent emergence of this clone. Transmission was facilitated by structural constraints, limited isolation capacity and shared sanitary facilities. This prolonged outbreak documents the re-emergence and genomic evolution of a hypervirulent RT027 lineage, characterized by a concerning expansion of antimicrobial resistance and decreased vancomycin susceptibility and a high recurrence rate (25%). These findings highlight the ongoing adaptive potential of C. difficile under antimicrobial pressure and underscore the need for strengthened surveillance, genomic monitoring, and infection-prevention strategies to mitigate re-establishment of epidemic RT027 strains in Europe and beyond.
- The impact of orthopoxvirus vaccination and Mpox infection on cross-protective immunity: a multicohort observational studyPublication . Crandell, Jameson; Pischel, Lauren; Fang, Zhenhao; Conde, Luciana; Zhong, Yi; Lawres, Lauren; Meira de Asis, Gustavo; Maciel, Gabriela; Zaleski, Agnieszka; Lira, Guilherme S.; Higa, Luiza M.; Breban, Mallery I.; Vogels, Chantal B.F.; Caria, João; Pinto, Ana Raquel; Almeida, Vasco; Maltez, Fernando; Cordeiro, Rita; Póvoas, Diana; Grubaugh, Nathan D.; Aoun-Barakat, Lydia; Grifoni, Alba; Sette, Alessandro; Castineiras, Terezinha M.; Chen, Sidi; Yildirim, Inci; Vale, Andre M.; Omer, Saad B.Background: Cross-reactive immune memory responses to orthopoxviruses in humans remain poorly characterised despite their relevance for vaccine design and outbreak control. We aimed to assess the magnitude, specificity, and durability of cross-reactive immune responses elicited by smallpox vaccines and mpox virus infection. Methods: We did a multicohort observational study involving participants from the USA, Brazil, and Portugal across four groups: Dryvax (first-generation smallpox vaccine) recipients vaccinated 40-80 years ago, JYNNEOS (third-generation smallpox vaccine) recipients vaccinated within the past year, a cohort receiving both vaccines, and patients infected with clade IIb mpox. Samples were analysed for systemic and mucosal humoral responses, neutralising antibody titres, viral antigen structural analysis, and T-cell cross-reactivity to vaccina virus, cowpox virus, and mpox virus. Statistical analyses included correlation assessments and comparisons across cohorts to determine the magnitude, longevity, and breadth of immune responses. Findings: Between July 7, 2022, and Aug 3, 2023, 262 participants were recruited, resulting in analysis of 378 samples. Both first-generation and third-generation smallpox vaccines elicited vaccinia virus-reactive and mpox virus-reactive antibodies, with the strongest responses targeting the less conserved extracellular virion antigens B5 and A33. Despite high concentrations of anti-mpox virus antibodies in the plasma, cross-neutralisation activity correlated with viral antigenic distance. Higher neutralisation was observed for cowpox virus than for mpox virus, which has lower antigenic conservation with vaccina virus. Complement-mediated neutralisation enhanced mpox virus neutralisation, overcoming the limitations of antigenic distance. Dryvax recipients sustained vaccina virus neutralisation titres for over 80 years, whereas cross-reactive responses did not show this durability. JYNNEOS-induced responses waned within a year. T-cell cross-reactivity was long-lasting, detected up to 70 years after vaccination. Booster vaccinations augmented the magnitude, breadth, and longevity of cross-neutralising responses. Interpretation: Our findings highlight the potential combined role of antibody effector functions and T-cell memory in cross-protection against orthopoxviruses. Complement-mediated neutralisation enhances cross-protection, overcoming antigenic distance. These Fc-mediated functions, along with T-cell responses, contribute to effective and long-lasting immunity conferred by smallpox vaccines against other orthopoxviruses.
- Influenza vaccine effectiveness in Europe and the birth cohort effect against influenza A(H1N1)pdm09: VEBIS primary care multicentre study, 2023/24Publication . Kissling, Esther; Maurel, Marine; Pozo, Francisco; Pérez-Gimeno, Gloria; Buda, Silke; Sève, Noémie; Domegan, Lisa; Hooiveld, Mariëtte; Oroszi, Beatrix; Martínez-Baz, Iván; Guiomar, Raquel; Latorre-Margalef, Neus; Mlinarić, Ivan; Lazar, Mihaela; Giménez Duran, Jaume; Dürrwald, Ralf; Enouf, Vincent; McKenna, Adele; de Lange, Marit; Túri, Gergő; Trobajo-Sanmartín, Camino; GOMEZ TEIXEIRA PINTO, VERÓNICA DEL PILAR; Samuelsson Hagey, Tove; Višekruna Vučina, Vesna; Cherciu, Maria Carmen; García Vazquez, Miriam; Erdwiens, Annika; Masse, Shirley; Bennett, Charlene; Meijer, Adam; Kristóf, Katalin; Castilla, Jesús; Rodrigues, Ana Paula; Kurečić Filipović, Sanja; Ivanciuc, Alina Elena; Bacci, Sabrina; Kaczmarek, MarlenaIntroduction: Influenza A(H1N1)pdm09, A(H3N2) and B/Victoria viruses circulated in Europe in 2023/24, with A(H1N1)pdm09 dominance. First influenza infections in childhood may lead to different vaccine effectiveness (VE) in subsequent years. Aim: The VEBIS primary care network estimated influenza VE in Europe using a multicentre test-negative study. Methods: Primary care practitioners collected information and specimens from patients consulting with acute respiratory infection. We estimated VE against influenza (sub)type and clade, by age group and by year of age for A(H1N1)pdm09, using logistic regression. Results: We included 29,958 patients, with 3,054, 1,053 and 311 influenza A(H1N1)pdm09, A(H3N2) and B cases, respectively. All-age VE against influenza A(H1N1)pdm09 was 52% (95% CI: 44-59). By year of age, VE was 27% (95% CI: -2 to 47) at 44 years with peaks at 72% (95% CI: 52-84) and 54% (95% CI: 41-64) among children and those 65 years and older, respectively. All-age A(H1N1)pdm09 VE against clade 5a.2a was 41% (95% CI: 24-54) and -11% (95% CI: -69 to 26) against clade 5a.2a.1. The A(H3N2) VE was 35% (95% CI: 20-48) among all ages and ranged between 34% and 40% by age group. All-age VE against clade 2a.3a.1 was 38% (95% CI: 1-62). All-age VE against B/Victoria was 83% (95% CI: 65-94), ranging between 70 and 92% by age group. Discussion: The 2023/24 VEBIS primary care VE against medically attended symptomatic influenza infection was high against influenza B/Victoria, but lower against influenza A(H1N1)pdm09 and A(H3N2). Clade- and age-specific effects may have played a role in the lower A(H1N1)pdm09 VE.
- Interim 2024/25 influenza vaccine effectiveness: eight European studies, September 2024 to January 2025Publication . Rose, Angela; Lucaccioni, Héloïse; Marsh, Kimberly; Kirsebom, Freja; Whitaker, Heather; Emborg, Hanne-Dorthe; Botnen, Amanda Bolt; O’Doherty, Mark G.; Pozo, Francisco; Shahul Hameed, Safraj; Andrews, Nick; Hamilton, Mark; Lauenborg Møller, Karina; Trebbien, Ramona; Marques, Diogo F.P.; European IVE groupThe 2024/25 influenza season in Europe is currently characterised by the co-circulation of influenza A(H1N1)pdm09, A(H3N2) and B/Victoria viruses, with influenza A(H1N1)pdm09 predominating. Interim vaccine effectiveness estimates from eight European studies conducted in 17 countries indicate an overall influenza A vaccine effectiveness of 32–53% in primary care settings and 33–56% in hospital settings, with some indications of lower effectiveness by subtype and higher effectiveness against influenza B (≥58% across settings). Where feasible, influenza vaccination should be encouraged and other preventive measures strengthened.
- Leishmaniasis retrospective analysis of cases diagnosed in the National Institute of Health between 2020 and 2024Publication . Reis, Tânia; Vilares, Anabela; Ferreira, Idalina; Martins, Susana; Gargaté, Maria JoãoAim: To describe the demographic characteristics of leishmaniasis cases, in patients with clinical symptoms, whose laboratory diagnosis was confirmed between 2020 and 2024 at the National Reference Lab of Parasitic and Fungal Infections.
- Low numbers of COVID-19 in the 2024/25 winter season: potential seasonality patternPublication . Rodrigues, Ana Paula; das Neves Pereira da Silva, SusanaBrief presentation analysing the possibility of a seasonal pattern of COVID-19 epidemics in Portugal, in the context of the VEBIS Annual Meeting.