Adults who received the bivalent RSV prefusion F vaccine experienced a lower incidence of respiratory syncytial virus-related respiratory hospitalizations compared to those who received no vaccine, according to expanded findings from the DAN-RSV trial presented at ESC Congress and simultaneously published in NEJM Evidence.
DAN-RSV Trial Results Show 70% Vaccine Effectiveness
The first year of the DAN-RSV trial randomized adults over 60 years old in Denmark to either the RSVpreF vaccine or no vaccine. Eligibility expanded in the second year to include adults over 18 from both Denmark and Spain, with the primary endpoint tracking RSV-related respiratory tract disease hospitalizations in the intention-to-treat population.
Mats C. Højbjerg Lassen, MD, MSc, PhD, and colleagues found that the incidence rate of RSV-related respiratory tract disease hospitalization was 0.16 events per 1,000 person-years in the RSVpreF group. That compares with 0.55 events per 1,000 person-years in the unvaccinated group, corresponding to an estimated vaccine effectiveness of 70%, according to the published data. All-cause respiratory tract disease hospitalization stood at 11.16 events per 1,000 person-years for vaccinated participants and 12.01 for unvaccinated individuals. Serious adverse events remained similar across both groups at approximately 2%.
Two-Season Protection and Re-Vaccination Questions
A separate DAN-RSV analysis led by Lassen and published in NEJM Evidence evaluated protection across two consecutive RSV seasons following a single vaccine dose for adults aged 60 and older. Researchers noted that vaccine effectiveness estimates appeared lower in the second season than in the first.
Helen Y. Chu, MD, MPH, and Kirby Erlandson, MD, MBA, emphasized in an accompanying editorial comment that determining optimal timing for re-vaccination remains a priority for future research. They wrote that higher-risk groups, including immunocompromised individuals and patients with underlying cardiopulmonary disease, need more targeted data. These data provide real-world evidence supporting RSV vaccination while highlighting the need to better define re-vaccination schedules.
Cardiovascular Safety and Atrial Fibrillation Outcomes
A prespecified safety analysis published in JACC examined the risk of myocarditis or pericarditis following RSVpreF vaccination. Marat Yafasov, MD, and colleagues reported that myocarditis or pericarditis proved exceedingly rare for RSVpreF, with no clear differences observed between vaccinated and unvaccinated participants.
Another JACC analysis evaluated vaccine effectiveness according to baseline atrial fibrillation status. Caroline Espersen, MD, and co-authors found that the vaccine reduced RSV-related respiratory and cardio-respiratory hospitalizations without treatment heterogeneity by atrial fibrillation status. Furthermore, the vaccine was not associated with higher mortality among atrial fibrillation participants in the expanded two-season cohort.
Frequently Asked Questions
What was the overall vaccine effectiveness in the DAN-RSV trial?
The estimated vaccine effectiveness against RSV-related respiratory tract disease hospitalization reached 70%, with an incidence rate of 0.16 events per 1,000 person-years in the vaccine group versus 0.55 in the unvaccinated group, according to Mats C. Højbjerg Lassen, MD, MSc, PhD, and colleagues.
Is the RSVpreF vaccine associated with an increased risk of myocarditis?
No. A prespecified safety analysis published in JACC by Marat Yafasov, MD, and fellow researchers found that myocarditis or pericarditis was exceedingly rare, showing no clear differences between vaccinated individuals and those who received no vaccine.
How does baseline atrial fibrillation affect vaccine outcomes?
According to Caroline Espersen, MD, and co-authors, the RSVpreF vaccine successfully reduced RSV-related respiratory and cardio-respiratory hospitalizations regardless of baseline atrial fibrillation status, with no association with higher mortality in that subgroup.
Explore More: Visit ACC’s ESC Congress coverage page to explore the latest science and key takeaways shaping cardiovascular care.
Keep reading