Queensland’s recent data reveal a promising 10% reduction in positive infant respiratory syncytial virus (RSV) tests following the introduction of the state’s free vaccination program. This significant development comes as global health experts continue to monitor RSV trends, particularly in the United States, where post-infection cardiorespiratory risks are under scrutiny.
In a study published in the Journal of Paediatrics and Child Health, researchers compared eligible infants—those three months or younger—against ineligible children aged 24-35 months. They found an absolute risk reduction in RSV of 6.9 percentage points. Specifically, positive tests in eligible infants dropped from 16% to 5.8% after the nirsevimab (Beyfortus) program’s introduction in April 2024, compared to 18.6% and 14.6% among ineligible infants.
Impact of Queensland’s Vaccination Program
The study analyzed 21,000 RSV PCR tests conducted in Queensland between 2022 and 2024, noting that the annual total of tests nearly doubled from 5,600 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 took a broader approach by considering the entire cohort under the age of two as “eligible.”
Researchers did not analyze data based on individual infant status, opting instead to use age brackets to compare high-risk first-season infants against those who could not have received a vaccination. This community-based study recorded percentages weekly, observing similar trends across age brackets until the vaccination program’s launch on April 15, 2024, when a notable drop in RSV cases was recorded in younger infants.
Rising RSV Cases and National Trends
According to the National Notifiable Diseases Surveillance System, there were 42,663 laboratory-confirmed cases of RSV in Queensland in 2024, marking a significant increase from the 28,791 cases in 2023 and 29,701 in 2022. Nationally, RSV cases in the first quarter of 2024 numbered 32,215, dropping to 24,194 in the first quarter of 2025. So far in 2026, there have been 8,348 cases, with 2,751 occurring in Queensland.
Meanwhile, a separate study using deidentified patient data from the US Optum Market Clarity Dataset examined the cardiorespiratory risk following RSV-related hospitalization between 2017 and 2024. Published in JAMA Network Open at the end of 2025, this self-controlled case series was based on diagnostic codes and highlighted significant health risks.
Cardiorespiratory Risks Post-RSV Infection
The US study included nearly 12,000 patients, with a mean age of 69 years, who had RSV and at least one cardiorespiratory event. The most common events were arrhythmia, chronic obstructive pulmonary disease (COPD) exacerbation, congestive heart failure (CHF) exacerbation, myocardial infarction (MI), and stroke.
“This study demonstrated that RSV, similar to influenza and SARS-CoV-2, was associated with an increased risk of cardiorespiratory events two weeks following RSV-related hospitalization, with some conditions showing significant risk elevations up to 180 days after admission,” authors wrote.
The study found that the first seven days following hospitalization yielded the highest incident rate ratios for cardiorespiratory events. COPD exacerbation showed the most significant initial risk, with a 23-fold increase. The incident rate ratio for MI was 8.7 in the first week, decreasing to 5.2 in the second week and 2.6 during the third week. Similar trends were observed for stroke, CHF exacerbation, arrhythmia, and COPD exacerbation.
Looking Ahead: Implications and Future Steps
The findings from Queensland and the US underscore the importance of RSV vaccination programs and the need for continued research into the virus’s long-term health impacts. As the global community grapples with rising RSV cases, these studies provide critical insights into effective prevention strategies and the broader implications of RSV infections.
Experts suggest that expanding vaccination programs and improving public health awareness could mitigate the virus’s impact, particularly among vulnerable populations. As new data emerge, health authorities worldwide will need to adapt strategies to address both the immediate and long-term challenges posed by RSV.
