Respiratory Diseases Roundup

Updates on RSV Prevention, Viral Metastasis, and Antiviral Safety

Miranda Manier, BA

Key Highlights:

  • The United States is terminating federal mRNA vaccine contracts, sparking concern from the WHO about pandemic readiness.
  • Maternal respiratory syncytial virus (RSV) vaccination reduced newborn RSV hospitalizations by approximately 80%.
  • Respiratory viruses like influenza and SARS-CoV-2 reactivated dormant breast cancer cells in lungs in animal models and were linked to worse outcomes in human survivors.
  • Oseltamivir was associated with reduced risk of serious neuropsychiatric events in children with influenza.

United States Terminates 22 mRNA Vaccine Contracts, Prompting WHO Alarm1

The US Department of Health and Human Services has canceled 22 federal contracts related to mRNA vaccine development, citing lack of efficacy against upper respiratory infections. The decision, led by Health Secretary Robert F. Kennedy Jr., halts federal investments and contracts on research involving late-stage development of mRNA-based influenza vaccines.

The WHO called the move “an unfortunate and untimely decision,” emphasizing the platform’s adaptability and importance for rapid vaccine development during pandemics. mRNA vaccines have demonstrated success during the COVID-19 pandemic and hold promise for emerging infectious diseases. The HHS plans to redirect funding to alternate platforms, though it has not provided detailed evidence to support its rationale. WHO officials expressed confidence that global research into mRNA vaccine technology will continue despite this federal withdrawal.

Maternal RSV Vaccine Reduces Infant Hospitalization2

A national report from Public Health Scotland found that maternal immunization with the new respiratory syncytial virus (RSV) vaccine significantly decreased RSV-related hospital admissions among infants. Among babies younger than 3 months, those born to vaccinated mothers were approximately 80% less likely to be hospitalized for RSV during the virus’s peak season. Since the program’s launch in August 2024, vaccine uptake reached 50% of eligible pregnant women. Over the first season, this uptake was associated with 228 fewer infant hospitalizations. The vaccine is administered from 28 weeks’ gestation, enabling transplacental antibody transfer to protect infants during their first 6 months—the period of highest vulnerability.

Respiratory syncytial virus is a leading cause of bronchiolitis and pneumonia in infants. Though usually causing mild symptoms, RSV can be severe in infants and older adults. The vaccine’s effectiveness underscores its potential to reduce the burden of pediatric respiratory hospitalizations. Clinicians and public health officials are advocating for increased uptake ahead of the next RSV season, with ongoing educational outreach to promote vaccination during pregnancy as a preventive strategy.

Respiratory Viruses May Trigger Breast Cancer Metastasis3

A recent study published in Nature demonstrated that respiratory viral infections, including influenza and SARS-CoV-2, can reactivate dormant breast cancer cells in the lungs in mouse models. Infected mice exhibited increased proliferation of previously quiescent HER2+ disseminated cancer cells (DCCs), leading to metastatic growth within two weeks of infection. This awakening of DCCs was driven by interleukin-6 (IL-6)–dependent inflammation and sustained by CD4+ T cell–mediated immune suppression of cytotoxic CD8+ T cells.

Human observational data aligned with the murine findings. Cancer survivors who contracted SARS-CoV-2 experienced significantly increased risks of cancer-related mortality and lung metastases. In the UK Biobank cohort, cancer survivors with COVID-19 had nearly double the risk of cancer death compared to those uninfected. Data from the Flatiron Health database also showed elevated lung metastasis risk in breast cancer survivors after COVID-19. These findings highlight the potential for respiratory infections to disrupt cancer dormancy and suggest possible roles for IL-6–targeted therapies in mitigating this risk.

Oseltamivir Linked to Reduced Neuropsychiatric Risk in Children4

In a large retrospective cohort study of nearly 700,000 children enrolled in Tennessee Medicaid, researchers found that oseltamivir treatment during influenza episodes was associated with a reduced risk of serious neuropsychiatric events. Neuropsychiatric hospitalizations—including seizures, mood disorders, and suicidal behaviors—were most common during influenza illness. However, children who received oseltamivir had a 47% lower risk of such events compared to those who did not receive treatment. The protective effect was particularly pronounced for neurologic events.

The study addressed prior concerns about oseltamivir's neuropsychiatric safety profile, which had prompted warnings based on case reports. Using validated outcome definitions and robust person-day–level exposure modeling, this study found no evidence of increased psychiatric risk and suggested a benefit for neurologic complications. The findings support oseltamivir’s continued use in pediatric influenza treatment, particularly for children at elevated risk of neurologic complications.

References:

  1. Al Jazeera. WHO says US ending mRNA vaccine contracts a “significant blow.” Published August 7, 2025. Accessed August 8, 2025. https://www.aljazeera.com/news/2025/8/7/who-says-us-ending-mrna-vaccine-contracts-a-significant-blow
  2. Public Health Scotland. New RSV vaccine results in encouraging reduction in hospitalisations for newborns. Published August 7, 2025. Accessed August 8, 2025. https://publichealthscotland.scot/news/2025/august/new-rsv-vaccine-results-in-encouraging-reduction-in-hospitalisations-for-newborns/
  3. Chia SB, Johnson BJ, Hu J, et al. Respiratory viral infections awaken metastatic breast cancer cells in the lung. Nature. 2025;S41586-025-09332-0. doi:10.1038/s41586-025-09332-0
  4. Antoon JW, Williams DJ, Bruce J, et al. Influenza with and without oseltamivir treatment and neuropsychiatric events among children and adolescents. JAMA Neurol. Published online August 4, 2025. doi:10.1001/jamaneurol.2025.1995