Respiratory Diseases Roundup

Emerging COVID Variants, Vaccine Funding Changes, and RSV Cardiac Risks

Miranda Manier, BA

Key Highlights

  • A new COVID-19 variant, NB.1.8.1, could lead to a mild summer uptick in cases.
  • The US Department of Health and Human Services has canceled $590 million in funding for Moderna’s H5N1 bird flu vaccine program.
  • Respiratory syncytial virus hospitalizations carry higher cardiac event risk compared to COVID-19 and influenza.

New COVID-19 Variant NB.1.8.1 Monitored1

A new COVID-19 variant, NB.1.8.1, has been identified in the United States and is spreading in parts of Europe, Southeast Asia, and the Americas. The variant appears more transmissible than the previously dominant strain LP.8.1. However, no evidence has emerged that NB.1.8.1 is more capable of evading vaccine protection or causes more severe illness. The CDC reports that fewer than 20 sequences have been detected in the United States, and the variant has not yet reached the threshold for CDC monitoring.

Federal and state health officials are tracking the variant’s potential to drive a mild-to-moderate increase in COVID-19 cases during the summer. COVID-19 vaccines are updated annually to target circulating strains, and the FDA has indicated that updated vaccines for LP.8.1 will be limited to older adults and younger individuals with medical conditions. Current data suggest that individuals who have not been vaccinated or had COVID-19 in some time may have reduced immunity to this variant.

HHS Cancels Moderna’s H5 Avian Influenza Vaccine Funding2

Moderna has announced that the US Department of Health and Human Services (HHS) has ended a $590 million award to support late-stage development of its candidate mRNA vaccine targeting H5 avian influenza. The funding was part of a broader effort initiated in January 2025 to prepare for potential pandemic influenza. HHS indicated that it reviewed and decided to terminate the contract in early March 2025. The decision occurs amid continued detection of H5N1 in livestock, poultry, and wild birds in the United States and other countries.

In the same announcement, Moderna reported positive interim phase 1/2 trial data on the H5 vaccine, involving 300 healthy adults. The study showed a rapid, potent, and durable immune response in 97.9% of participants. Moderna stated that it would explore alternative strategies for the late-stage development of the H5 vaccine to continue addressing pandemic preparedness.

RSV Hospitalizations Linked to Higher Cardiac Risks3

A population-based cross-sectional study published in JAMA Network Open analyzed 32,960 hospitalizations for respiratory viral infections in Singapore from 2017 to 2024. The study compared the risk of acute cardiovascular events in patients hospitalized for respiratory syncytial virus (RSV), influenza, or COVID-19 during Omicron transmission. It found that 10.9% of patients hospitalized for RSV had an acute cardiovascular event, with significantly higher odds of dysrhythmia, heart failure, and other cardiac complications compared with COVID-19 and influenza hospitalizations.

The study also showed that cardiovascular events during RSV hospitalizations were associated with greater odds of requiring intensive care unit admission. The authors concluded that vaccination against respiratory viral infections may play a role in reducing the risk of acute cardiovascular complications in hospitalized patients, especially for individuals with preexisting cardiac conditions.

References:
1. Bendix A. A new Covid variant could drive up summer cases: here’s what you should know. NBC News. May 29, 2025. Accessed May 30, 2025. https://www.nbcnews.com/health/health-news/new-covid-variant-nb181-vaccines-cases-what-know-rcna209465

2. Schnirring L. HHS cancels funding for Moderna’s candidate H5 avian flu and pandemic vaccines. Center for Infectious Disease Research and Policy. May 29, 2025. Accessed May 30, 2025. https://www.cidrap.umn.edu/avian-influenza-bird-flu/hhs-cancels-funding-moderna-s-candidate-h5-avian-flu-and-pandemic-vaccines

3. Wee LE, Lim JT, Ho RWL, et al. Cardiac events in adults hospitalized for respiratory syncytial virus vs COVID-19 or influenza. JAMA Netw Open. 2025;8(5):e2511764. doi:10.1001/jamanetworkopen.2025.11764