Background and Aim: This study assessed adjuvanted RSVPreF3 vaccine effectiveness (VE) against overall and RSV-related MACE and severe exacerbations of COPD or asthma in US adults at risk of these events.

Methods and Analysis: This retrospective cohort study used Optum Research Database claims to estimate adjuvanted RSVPreF3 VE in US adults aged ≥60 identified between Aug 2023–May 2024. Vaccinated patients’ index date was vaccination date; each was matched 1:4 to unvaccinated controls (assigned same index date as match) by age, sex, insurance type, and state. Baseline characteristics were measured 12 months pre‑index (continuous enrollment required). Follow‑up began 14 days post‑index. Censoring occurred at disenrollment, death, RSV vaccination, or analysis end. Overall and RSV‑related outcomes were assessed (occurring during any hospitalisation or RSV‑related hospitalisation, respectively). Propensity score-based weighting was used to balance baseline characteristics; Cox proportional hazards models estimated hazard ratios. VE was calculated as (1 – Hazard Ratio) × 100%.

Outcomes: The analysis included 520,440 vaccinated and 2,081,760 unvaccinated patients (mean [SD] age: 74.3 [6.7] years; 56.9% female). A total of 869,980 (33.4%) had underlying cardiovascular disease (CVD), 362,615 (13.9%) had underlying COPD, and 244,226 (9.4%) had underlying asthma. Among adults with CVD, VE against overall and RSV-related MACE was 20.4% (95% CI: 18.0–22.9%) and 63.1% (41.8–76.6%), respectively. In adults with underlying COPD or asthma, VE against RSV-related severe COPD and asthma exacerbations was 74.4% (59.3–83.9%) and 61.6% (9.1–83.7%), respectively.

Conclusion and Future actions: Findings suggest a considerable benefit of adjuvanted RSVPreF3 vaccination in preventing RSV-related MACE and severe asthma/COPD exacerbations among adults aged ≥60 years.

Encore from RSVVW’ 2026.

Background and Aim: Varicella and herpes zoster are vaccine-preventable diseases caused by varicella-zoster virus (VZV). Despite the availability of effective vaccines in Australia, VZV-related hospitalisations continue to occur. We examined the epidemiology of VZV-related hospitalisations in Central Queensland (CQ) and estimated vaccine effectiveness (VE) against hospitalisation.

Methods and Analysis: We conducted a retrospective population-based data linkage study of hospitalisations from January 2015 to December 2025, linking the Hospital-Based Corporate Information System with the Australian Immunisation Register. Admissions with a primary ICD-10 diagnosis of varicella or herpes zoster were included. Incidence rates per 100,000 population were calculated and incidence rate ratios estimated using Poisson regression. Vaccine effectiveness was assessed using a nested 1:20 age-matched case–control design with conditional logistic regression, and calculated as (1−OR) × 100%.

Outcomes: A total of 207 VZV-related hospitalisations were identified, comprising 43 varicella (20.8%) and 164 herpes zoster (79.2%) cases. Herpes zoster predominantly affected adults aged ≥60 years (64.0%), whereas varicella occurred more often in those aged <40 years (41.9%) (p<0.001). Median length of stay was 3.0 days (IQR 1.0–5.5) for varicella and 2.0 days (IQR 1.0–4.0) for herpes zoster (p=0.052). ICU admission was 2.3% for varicella and 0.6% for herpes zoster. Across all years, herpes zoster incidence exceeded varicella (3.0–14.2 vs 0.9–3.2 per 100,000). No varicella cases had prior vaccination, and 4.3% of herpes zoster cases were vaccinated before admission. Overall, VE for ≥1 dose against VZV-related hospitalisation was 81.9% (95% CI 58.1–92.2); for herpes zoster, VE was 74.8% (95% CI 41.5–89.1).

Conclusion and Future actions: Herpes zoster accounts for the majority of VZV-related hospital burden in CQ. Vaccination was strongly protective against hospitalisation; yet uptake among hospitalised cases was low. Improving zoster vaccination coverage in eligible adults and maintaining high varicella vaccine coverage remains critical to reducing severe VZV disease in regional Queensland.

Background and Aim: QLD Health introduced a universal Nirsevimab program for prevention of RSV in infants in April 2024. Studies on hospital and test positivity data suggest large reductions in the burden of infant RSV disease, increasing further with introduction of maternal immunization in late 2024. However, there has been limited analysis of changes in RSV notifications in infants. In this study, we estimate the per-dose and cumulative effectiveness of the QLD program on RSV notifications in infants.

Methods and Analysis: A panel regression model tracking infection in monthly birth cohorts was used to estimate the per-dose reduction in RSV notifications associated with observed Nirsevimab coverage, while adjusting for seasonality and age-specific infection risk. The regression model also accounted for measurement error in Nirsevimab coverage and assuming a 6-month period of effectiveness for the mAb. The model was applied to RSV notification data stratified by birth and calendar month from Queensland covering the calendar years 2023 and 2024 and children aged between 0 and 60 months and fitted in a Bayesian framework, using the STAN package.

Outcomes: According to Australian Immunisation Register (AIR) data, just under 32,000 doses of Nirsevimab were delivered during 2024 in QLD, with mass distribution beginning the week of April 8. We estimated that within the assumed 6 month period of effect, Nirsevimab doses had an effectiveness of 76% (95%CI 69-82%) in preventing notified infection. We estimate that the program prevented about 1/3rd of notifications in infants <6 months in 2024.

Conclusion and Future Actions: Despite an absence of individual vaccination status data, we derived robust estimates of the impact of the nirsevimab program in QLD in 2024, as well as the hypothetical burden if the program had not been introduced or had achieved full coverage. Under-reporting of doses to AIR may imply the per-dose effectiveness is an over-estimate.

Background and Aim
Respiratory Syncytial Virus (RSV) is a leading cause of acute respiratory illness in infants. A long-acting monoclonal antibody (nirsevimab), was introduced for vulnerable infants in the ACT in 2024, followed by a combined maternal and infant immunisation program in 2025. We evaluated the effectiveness of these interventions.

Methods and Analysis
This observational cohort study included all ACT-resident infants aged <2 years with laboratory-confirmed RSV and/or receipt of nirsevimab during the 2022-2025 winter seasons. Outcomes included emergency department (ED) presentations, hospitalisations, clinical severity indicators, and hospital costs.

We identified 2,792 RSV cases, including 1,890 ED presentations and 803 hospitalisations. Among 805 infants receiving nirsevimab, 1.6% experienced breakthrough RSV infection. Compared with baseline seasons, RSV-related ED presentation rates decreased in 2025 (44.41 to 39.84 per 1,000 infant-years), as did hospitalisations (18.25 to 16.81 per 1,000 infant-years). The effect was greater in infants aged <6 months (ED: 56.85 to 32.08; hospitalisations: 33.25 to 15.85 per 1,000 infant-years). Relative reductions were 46.4% for ED presentations and 61.8% for hospitalisations.

Among hospitalised infants, length of stay decreased by 16.8 hours (p<0.001) and use of respiratory support by one third (p<0.001). The effect was again greater in infants <6 months (length of stay by 22.1 hours, p<0.001; respiratory support by 41%, p<0.001).

Hospital costs decreased for all‑cause bronchiolitis ED presentations by 16.7%, and for RSV‑coded hospitalisations by 43.7%; in younger infant's costs decreased by 30.0% and 50.6%, respectively.

Outcomes
Maternal vaccination and birth-dose nirsevimab has become business-as-usual in our health service, while catch-up nirsevimab transitions to primary care.

Conclusions and future actions
The combined maternal and infant RSV immunisation program substantially reduced disease burden and healthcare costs in the ACT, particularly among infants aged <6 months. We now shift our attention to better understanding the factors associated with uptake of novel RSV immunisations.

Background and Aim: In November 2023, Shingrix® replaced Zostavax® on the National Immunisation Program (NIP) and eligibility for free Herpes Zoster (HZ) vaccine was expanded to all adults aged ≥ 65 years and immunocompromised adults aged ≥18 years. We aimed to assess the impact of the Shingrix program and estimate the vaccine effectiveness (VE) of Shingrix.
Methods and Analysis: Using linked data from the Person Level Integrated Data Asset (PLIDA), antiviral dispensing for HZ treatment, reported to the Pharmaceutical Benefits Scheme (PBS) was used as a proxy outcome and analysed ecologically from 2014–2025. From November 2023 to June 2025, vaccine effectiveness was estimated using survival analysis in cohorts aged ≥65 years (65+ cohort) and pharmacologically immunocompromised adults (≥18 years), with time-varying vaccination status extracted from the Australian Immunisation Register.
Outcomes: From late 2016, antiviral prescriptions declined among 70–79 year olds corresponding to the introduction of Zostavax® on the NIP (from 3.84 to 2.61/1,000). From early 2024, further declines were observed, among those aged ≥ 65 years aligning with the introduction of Shingrix® on the NIP and expanded eligibility. By 30th June 2025, 35% of 4.5 million adults in the 65+ cohort and 22% of the 239,002 adults in the pharmacologically immunocompromised cohort had received 2 doses of Shingrix®. Shingrix® VE against the proxy outcome showed that compared to those not vaccinated, 2 doses of Shingrix® was 63% (95%CI 62%, 64%) and 43% (95%CI 38%, 49%) effective in the 65+ cohort and the pharmacologically immunocompromised cohort respectively.
Conclusion and Future actions: Shingrix® demonstrated good protection against HZ in older adults, with lower effectiveness in the pharmacologically immunocompromised population. Continued evaluation of coverage and duration of effectiveness is needed, particularly in the immunocompromised population where disease burden is high, vaccine uptake is suboptimal and vaccine appears less effective.

Background and Aim

Mpox, caused by Monkeypox virus (MPXV), emerged globally in 2022, resulting in sustained transmission across 116 countries and more than 92,000 confirmed cases by the end of 2023. Critical uncertainties remain regarding the durability and breadth of humoral immunity following natural infection and vaccination with Modified Vaccinia Ankara–Bavarian Nordic (MVA-BN). Clarifying antibody kinetics, antigenic targets, and correlates of protection is essential to inform vaccination strategies, serosurveillance, and outbreak preparedness. This study aimed to systematically synthesise the evidence describing humoral immune responses following Mpox infection and MVA-BN vaccination.

Methods and Analysis

A systematic review and meta-analysis was conducted of published studies reporting serological outcomes following confirmed Mpox infection or MVA-BN vaccination. A total of 1,608 titles and abstracts were screened, with 110 studies meeting eligibility criteria for qualitative and quantitative synthesis. Data were extracted on seroconversion rates, longitudinal antibody persistence, antigenic targets, and documented breakthrough or reinfection events. Quantitative analyses compared antibody dynamics across exposure types and timepoints.

Outcomes

Both Mpox infection and MVA-BN vaccination induced high rates of seroconversion. However, longitudinal antibody dynamics differed substantially: infection-associated responses persisted for at least 12 months, whereas vaccine-induced titres began declining from approximately eight weeks post-vaccination. Structural proteins mediating virion entry and fusion were consistently identified as dominant immunogenic targets. Limited data on breakthrough and reinfection events suggest incomplete understanding of protective thresholds.

Conclusion and Future actions

Evidence indicates robust but heterogeneous humoral responses following infection and vaccination. Standardised serological assays, longer-term follow-up studies, and defined correlates of protection are urgently required. Future work should integrate serology with clinical and epidemiological data to optimise vaccination policy and strengthen outbreak preparedness.

Background and Aim:
Whooping cough (pertussis) remains a major public health challenge in Australia, with recurrent outbreaks partly due to waning vaccine-induced protection. As durable protection is influenced by the quality of vaccine-induced memory T-cell responses, we aimed to develop an activation-induced marker (AIM) assay to enumerate and immunophenotype pertussis-specific memory T-cells, crucial for evaluating new pertussis vaccines and schedules.

Methods and Analysis:
Peripheral blood mononuclear cells were stimulated with a commercial mega-pool of Bordetella pertussis 15-mer peptides (including epitopes within pertussis toxin, filamentous haemagglutinin and pertactin) or anti-CD3/CD28 beads (positive control). A healthy donor sample was included between runs as an internal/QC control. A 15-colour spectral flow cytometry panel was developed to assess CD4⁺/CD8⁺ T-cells, their naive, central(Tcm)- and effector memory subsets, CXCR5⁺ circulating follicular helper T-cells and Th1/2/17 polarisation. Antigen-specific T-cells were identified by upregulation of activation markers (CD69, 4-1BB, OX40 and CD40L) following peptide culture. Antibody concentrations, staining conditions, and peptide doses were optimised to maximise signal-to-background and validated in baseline and post-vaccination samples from a bio-banked adult Tdap vaccine trial (ACTRN12619000944134).

Outcomes:
Peptide stimulation for 24 hours was optimal at 0.5µg/mL, yielding the highest signal-to-background ratios. Anti-CD3/CD28 beads and QC AIM⁺ responses were stable across runs. CXCR3 was the only marker downregulated upon 24-hour culture (2.6-fold decrease) but was restored by pre-culture staining. In Tdap-vaccinated young adults, pertussis AIM⁺ Tcm responses were predominantly CD4⁺ T-cells. Boolean pairwise analysis of all AIM markers showed no single pair captured total AIM⁺ responses for CD4⁺ Tcm, however OX40⁺CD40L⁺ represented the majority (57.9%) of this response. CD4⁺OX40⁺CD40L⁺ Tcm responses peaked at day 28 and was on average 6.2‑fold greater than pre-boost frequencies.

Conclusion and Future actions:
Our AIM assay enables detailed profiling of pertussis‑specific memory T-cells. Ongoing work will compare responses in whole-cell versus acellular‑primed cohorts to identify T‑cell features associated with durable immunity, informing pertussis booster strategies and vaccine design.

Background and Aim
Dengue, a mosquito-borne disease, remains a major public health threat in Vietnam. While traditional vector control is well-established, dengue vaccination has only been available in private services in Vietnam since September 2024. This study evaluates general dengue knowledge and vaccine uptake among patients and matched controls.

Methods and Analysis
This pilot matched case–control study, conducted in two rural hospitals in An Giang, Vietnam (Oct–Dec 2025), recruited 35 cases and 70 controls matched 1:2 by gender and age (±5 years). A structured questionnaire was used to assess knowledge of dengue symptoms, mode of transmission, vector characteristics, prevention, and vaccination. Crude odds ratios (ORs) with 95% CIs were calculated using conditional logistic regression.

Outcomes
Overall, knowledge of dengue transmission and prevention was high (>80%) in both groups; however, significant knowledge gaps were observed. Compared to controls, cases were less likely to correctly identify mosquito-borne transmission (80.0% vs 95.7%; OR=0.16, 95% CI: 0.03–0.77, p=0.023), the primary vector (45.7% vs 68.6%; OR=0.35, 95% CI: 0.14–0.88, p=0.025), peak biting time (8.6% vs 25.7%; OR=0.26, 95% CI: 0.07–0.97, p=0.045), and at least one accurate breeding site (65.7% vs 91.4%; OR=0.15, 95% CI: 0.04–0.53, p=0.003). Recognition of symptoms, breeding season, and general prevention showed no significant differences between groups.
In contrast, awareness of dengue vaccination was notably low. Only 2.9%; 1 case and 2 controls, spontaneously mentioned vaccination as a preventive method. Only one participant (0.95%), a control, reported having received a dengue vaccination.

Conclusion and Future Actions
After 30 years of traditional dengue communication in Vietnam, basic dengue knowledge does exist but has not translated into the adoption of newer vaccine technologies. These preliminary findings highlight the need for updated communication strategies that integrate vaccination and improve public accessibility. Larger studies are necessary to confirm these observations and explore barriers to vaccine acceptance.

Background and Aim
After conjugate pneumococcal vaccines were added to the National Immunisation Program in 2005, the incidence of invasive pneumococcal disease (IPD) due to serotype 4 (ST4) was greatly reduced. Since 2024, Victoria has seen a large increase in ST4 invasive infections. Enhanced surveillance data were analysed to inform future vaccination and prevention programs.

Methods and Analysis
IPD data from the Victorian Public Health Event Surveillance System (PHESS) from 2016-2025 were analysed.

Outcomes
From 2016-2021, ST4 comprised <1% of serotypes causing IPD in Victoria, rising to 11% in 2024 and 15% in 2025. Multilocus sequence typing (MLST) was performed on all ST4 cultures in 2024-2025, with 163/176 (93%) being MLST 2759 (ST4-2759).
Of the 163 ST4-2759 cases in 2024-2025:
• Ages ranged from 16-82 years, with 85% aged 30-69 years.
• Aboriginal and Torres Strait Islander people were 5 times more likely to have ST4-2759 cases than other types.
• Cases aged 30-69 years notified with Hepatitis C since 1990 were 9 times more likely to have ST4-2759 than other types.
• Fourteen (14/163; 9%) ST4-2759 cases had been vaccinated, including four cases who had received 7-valent pneumococcal conjugate vaccines >15 years prior.
• Among the ST4-2759 cases who were not vaccinated, 20/149 were eligible for funded pneumococcal vaccination. Of the 129/149 ineligible for funded vaccination, 92/129 (71%) had risk conditions indicating vaccination was recommended, with over 80% of those aged ≥20 years being smokers.

Conclusion and Future actions
Many ST4-2759 infections should be preventable if all those known to be at risk for IPD are vaccinated. As health-seeking behaviours vary, a variety of targeted programs may be required. Analyses are underway to determine whether previously notified Hepatitis C cases have sought treatment for this condition, and the level of homelessness and/or current injecting drug use among this group.

Introduction: Adult pneumococcal vaccination and herd protection from childhood immunisation have reduced vaccine-type disease in Australian adults; however, a residual burden persists largely from serotypes not covered in current vaccines. Higher-valency pneumococcal conjugate vaccines (PCVs) therefore would provide additional benefit and estimates of vaccine preventable pneumococcal community-acquired pneumonia (PnCAP) and invasive pneumococcal disease (IPD) are needed.

Methods: We estimated PnCAP and IPD cases potentially averted by 13-, 15-, 20- and 21-valent PCVs in non-Indigenous adults aged ≥65 years. Australian Institute of Health and Welfare National Hospital Morbidity Database data (2017/18–2018/19) were used to identify CAP hospitalisations using ICD-10 codes for pneumococcal pneumonia (J13) and lobar pneumonia (J18.1). Consistent with published literature, 14% of pneumonia hospitalisations coded as unspecified causes (J15.9, J18.0, J18.2, J18.8, J18.9) were assumed pneumococcal to derive total PnCAP hospitalisations. IPD notifications for 2023–24 from the National Notifiable Diseases Surveillance System were used to determine proportions attributable to serotypes included in different PCVs. These proportions were applied to PnCAP, assuming similar serotype distributions.

Results: Annual average numbers of IPD were 769 and 8397 PnCAP hospitalisations in non-Indigenous adults aged ≥65 years during the study period. PnCAP accounted for 13.4% of total adult CAP hospitalisations (n= 62,346 per year). The proportions of IPD due to the vaccine serotypes were 26% for 13v, 44% for 15v, 58% for 20v and 78% for 21v-PCVs. Applying these proportions, annual cases potentially averted in these adults by the use of 13v, 15v, 20v and 21v PCVs respectively, for IPD were 203, 337, 446 and 599 and for PnCAP were 2193, 3711, 4892 and 6579.

Conclusion: In adults one in seven CAP hospitalisations was due to pneumococcus, and PnCAP burden was nearly eleven times that of IPD. Higher-valency vaccines could avert substantial additional disease compared with 13vPCV in the National Immunisation Program.