DDI - Apresentações orais em encontros internacionais
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- Do COVID-19 and Influenza vaccines influence susceptibility to other respiratory viruses? A population based studyPublication . Almeida Santos, João; Gomez, Verónica; Guiomar, Raquel; Verdasca, Nuno; Gomes, Licínia; Machado, Ausenda; Rodrigues, Ana PaulaIntroduction: Studies have raised concerns that Influenza and COVID-19 vaccination may influence susceptibility to other respiratory viruses (ORV), potentially increasing the risk of non-target infections. This challenges a key assumption of test-negative design studies—that vaccines do not affect the risk of other infections within the same clinical syndrome. Nevertheless, current evidence remains inconclusive. This study aimed to evaluate the association between COVID-19 and influenza vaccination and the risk of non-influenza/COVID-19 respiratory virus infections. Methods: Test-negative design (TND) study using Portuguese data from a primary care vaccine effectiveness study (VEBIS Primary Care study) between October/2022-April/2025. Data on influenza/COVID-19 vaccination status, age, sex and chronic conditions were collected. Samples were tested by RT-PCR for influenza, SARS-CoV-2 and ORV. Patients with laboratory-confirmed influenza/COVID-19 infection were excluded. Logistic regression estimated adjusted odds ratios (aOR) of being vaccinated among cases (ORV positive) and controls (pan-negative). Results: Of the 1096 patients included, 4.5% received the COVID-19 vaccine, 5.9% the influenza vaccine, 13.3% both, and 76.3% neither. Human Rhinovirus (44.2%), human Coronavirus (14.6%) and Respiratory Syncytial Virus (14.1%) were the viruses more frequently identified. Individuals 65+ exhibited significant lower odds of infection with ORV (OR=0.45, 95%CI:0.25-0.81) compared to younger age group (<18yo). Vaccination status, including influenza only (aOR=1.01, 95%CI:0.59‐1.72), COVID only (aOR=0.88, 95%CI:0.48‐1.59), and both vaccines (aOR=1.38, 95%CI:0.92‐2.06), were not associated to ORV infection risk. Conclusions: Our results suggest that vaccination status—whether for influenza, COVID-19, or both—was not significantly associated with the risk of ORV infections. This supports the use of test-negative controls for influenza/COVID-19 within the same clinical syndrome, as it upholds a key TND assumption of no association between vaccination and risk of non-target infections. While mechanisms such as reduced cross-protection from natural infection or potential vaccine-induced cross-immunity have been proposed, our findings reinforce the validity of the primary methodological assumption rather than suggesting evidence for these alternative effects.
- Impact of a revised late HIV diagnosis definition on late HIV estimates in Europe: A multi-country pilot studyPublication . Kirwan, P.; Stengaard, A.; Brännström, J.; Van Beckhoven, D.; van Sighem, A.; Op de Coul, E.; Bartmeyer, B.; Koppe, U.; C. Martins, H.; Maly, M.; Wessman, M.; Tsiara, C.; Ferentinos, G.; Suligoi, B.; Grabar, S.; Sullivan, A.K.; Reyes, J.; Pharris, A.; Kuchukhidze, G.; Kirk, O.; Croxford, S.; Delpech, V.; Raben, D.; EuroTEST Steering CommitteePurpose: Late HIV diagnosis has been defined as a CD4 count <350 cells/mL or AIDS-defining event. With improvements in HIV tests and testing frequency, more people in Europe are diagnosed during the acute/seroconversion phase, when their CD4 count can be temporarily low. A revised consensus definition of late HIV diagnosis* enables better distinction between people diagnosed late and those diagnosed during the acute/seroconversion phase. We aimed to pilot this revised definition with European countries. Method: Pseudo-anonymised HIV diagnosis records for 2022-2023 were collected from nine countries. Records included markers of recent HIV acquisition from laboratory evidence (RITA, p24), testing history (negative HIV test within 12 months), or clinical evidence (e.g. seroconversion illness). We applied the revised definition to reclassify those with recently acquired HIV as ‘not-late’. Late diagnosis correction factors were calculated as: (number reclassified)/(number with CD4<350 or AIDS-defining event) and evaluated by demographic factor. Results: Availability of recent acquisition evidence varied by country and individual marker. Of 10,241 diagnoses with CD4 counts reported, 56% (5,696/10,241) had a CD4<350 or AIDS-defining event, i.e. were initially classified as late. Of these, 563 had evidence of recent HIV acquisition: 168 had laboratory evidence, 238 testing history evidence, and 260 clinical evidence (could have multiple). After reclassification the late diagnosis rate was reduced from 56% to 50%,with an overall correction factor of 10% (563/5,696), ranging between 3-25% across countries . The correction factor was higher for younger individuals compared to older, and for MSM compared to other transmission routes . Conclusions: Without reclassification, late HIV diagnosis rates are overestimated, by up to 25% in young MSM. This correction addresses a lack of progress in reducing the percentage of people diagnosed late. For countries to undertake this correction, improved collection of recent acquisition markers at clinic and national levels is needed.
- 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.
- Molecular characterization of Neisseria meningitidis strains causing non-invasive disease in Portugal from 2012-2024Publication . Bettencourt, Célia; Camões, InêsIntroduction: Non-invasive meningococcal disease (NIMD) is not notifiable, and the prevalence of serogroups and antimicrobial resistance (AMR) are unknown. This study aims to investigate the genetic diversity of non-invasive isolates identified in Portugal (2012-2024), assess their genomic relationships with Portuguese invasive isolates and identify AMR profiles. Material and Methods: All non-invasive N. meningitidis isolates were characterized by whole genome sequencing and the sequences submitted to the PubMLST/Neisseria.database. For antimicrobial susceptibility testing, antibiotic gradient strip diffusion (Etest) was used. Results: A total of 141 non-invasive isolates were characterized by WGS with 88% identified from respiratory secretions. Serogroup B was the most prevalent (40.4%), followed by serogroups Y (10.6%), C and E (3.5% each), W, X and Z (1.4% each). Capsule null (cnl) isolates accounted 33.3%. In silico analysis revealed the main clonal complexes (cc): B-cc41/44 (21%) and cc162 (14%), Y-cc23 and cc103 (33.3% each) and cnl-cc53 (38.3%). Isolates belonging to cc11 were predominantly serogroup C (40%) and only 1 isolate was identified as serogroup W. All isolates were sensitive to ceftriaxone and 67.9% of the isolates were penicillin-nonsusceptible, while 2.9% and 3.9% were resistant to ciprofloxacin and rifampicin, respectively. Conclusions: In this study, we identified non-invasive populations with similar genetic diversity when compared to invasive populations in previous studies[1]. In contrast, NIM isolates showed increased levels of resistance to penicillin and several isolates showed resistance to antibiotics used in IMD prophylaxis. These results emphasise the need for more studies on AMR among meningococci in order to ensure the effective use of antibiotics in the treatment of meningococcal disease.
- Surveillance of invasive meningococcal disease in Portugal, from 2020 to 2024Publication . Bettencourt, Célia; Nunes, A.; VigLab-DM – Network for the Laboratory Surveillance of Meningococcal Disease; Bajanca-Lavado, M.P.; .Introduction: Since 2002, laboratory surveillance of Invasive Meningococcal Disease (IMD) has been carried out by the National Reference Laboratory for Neisseria meningitidis, at the National Institute of Health Doutor Ricardo Jorge, Portugal. This study aims to analyse the epidemiology of IMD and the genetic diversity of Neisseria meningitidis strains from 2020 to 2024. Material and Methods: Suspected IMD cases and N. meningitidis isolates were sent to the reference laboratory for confirmation and strain characterization. Invasive isolates were characterized by WGS (Illumina) and sequences were submitted to the PubMLST/Neisseria database. Results: Between 2020 to 2024, 125 IMD cases were confirmed. Annual incidence rate ranged from 0.36 cases/100,000 inhabitants in 2020 to 0.32 in 2023 [1, 2]. Serogroup B was the most prevalent (49.6%), followed by serogroups Y (14.4%), W (13.6%) and C (5.6%). Serogroup W mainly affected those over 45 years old (58.8%). In silico analysis of 89 (71.2%) isolates identified major clonal complexes (cc): B-cc213 (22%) and cc41/44 (18%), Y-cc23 (80%), W-cc11 (66.7%), and C-cc11/cc103 (33.3% each). Conclusions: Compared to previous studies (2003-2020), the incidence of IMD in Portugal has decreased [1-3]. However, serogroup B remains the leading cause of IMD, raising concerns, particularly due to cases in children and emerging clusters with low vaccination coverage (e.g. serogroup B cc213) [4]. In contrast, serogroup W cases have increased, especially among adults [2, 3]. This study highlights the importance of laboratory surveillance for understanding IMD epidemiology and monitoring long-term trends.