Prevention shows early impacts in Queensland, while US data highlight trends in post-infection cardiorespiratory risk.
Queensland data has shown a 10% reduction in positive infant respiratory syncytial virus tests following the introduction of the state’s free vaccination program.
When comparing eligible infants (three months or younger) against ineligible children (aged 24-35 months), researchers found an absolute risk reduction in RSV of 6.9 percentage points.
Positive tests in eligible infants dropped from 16% to 5.8% following the nirsevimab (Beyfortus) program introduction in April 2024, compared to 18.6% and 14.6%, respectively, among ineligible infants.
The study, published in the Journal of Paediatrics and Child Health, is the first real-world community-based evidence on the impact of nirsevimab on RSV detection percentages in infants, authors wrote.
The study analysed the 21,000 RSV PCRs that were performed in the state between 2022 and 2024 in children in these age brackets. The annual total of tests nearly doubled in this time, from 5600 in 2022 to 10,500 in 2024.
While vaccine eligibility required infants to be aged between three and eight months if healthy, or between three months and under two years if risk factors were present, the study was community-based and considered the entire cohort under the age of two to be “eligible”.
The researchers did not analyse data based on individual infant status, and instead used age brackets to compare the highest-risk first-season infants against those who could not possibly have received a vaccination (as eligibility ends at 24 months).
Percentages were recorded weekly across the study period, with similar trends seen across the age brackets at each timepoint leading up to the vaccination program launch on April 15, 2024, when a significant drop was noted in the younger age bracket.
According to the National Notifiable Diseases Surveillance System (accessed 20/2/26), there were 42,663 laboratory-confirmed cases of RSV in Queensland in 2024, a significant increase from 2023 and 2022, which saw 28,791 and 29,701 cases, respectively.
Nationally, there were 32,215 laboratory-confirmed cases of RSV in the first quarter of 2024, which dropped to 24,194 in the first quarter of 2025. There have been 8348 of RSV so far in 2026, 2751 of which have occurred in the sunshine state.
Another recent study, looking at deidentified patient data from the US Optum Market Clarity Dataset, assessed the cardiorespiratory risk in the 180 days following RSV-related hospitalisation between 2017 and 2024.
The self-controlled case series was published in JAMA Network Open at the end of 2025 and was based on diagnostic codes.
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Nearly 12,000 patients (61% female, mean age 69 years) with RSV and at least one cardiorespiratory event were included. The most frequently observed cardiorespiratory events were arrhythmia (n = 5844), chronic obstructive pulmonary disease exacerbation (n = 5018), congestive heart failure exacerbation (n = 4204), myocardial infarction (n = 2421) and stroke (n = 1622).
The findings suggested that hospitalisation due to RSV increased risk of MI, stroke, COPD exacerbation, CHF exacerbation and arrhythmia, most significantly in the first few weeks.
Across all cardiorespiratory events, the first seven days following hospitalisation yielded the highest incident rate ratio estimates. COPD exacerbation showing the most significant initial risk, with a 23-fold increase.
In the first week, the incident rate ratio for MI was 8.7, decreasing to 5.2 in the second week and 2.6 during the third week. Results followed similar trends with varying magnitudes for stroke (7.4, 5.9 and 3.7), CHF exacerbation (12.5, 4.1 and 2.4), arrhythmia (16.5, 4.9 and 1.6) and COPD exacerbation (23.1, 4.6 and 1.3).
“This study demonstrated that RSV, similar to influenza and SARSCoV-2, was associated with an increased risk of cardiorespiratory events 2 weeks following RSV-related hospitalization, and some conditions had significant risk elevations up to 180 days after admission,” authors wrote.
