Top 5 Infectious Disease News Stories Week of June 7-June 14

FDA Expands Moderna’s mRNA-1345 RSV Vaccine to Younger Adults

The FDA has expanded approval of Moderna’s mRNA-1345 (mRESVIA) respiratory syncytial virus (RSV) vaccine to include adults aged 18 to 59 years, following its initial approval for those 60 and older to prevent lower respiratory tract disease caused by RSV. This decision was based on Moderna's phase 3 trial demonstrating that the vaccine elicited comparable immune responses in younger adults with underlying health conditions as seen in older adults, meeting non-inferiority criteria. The approval aims to protect at-risk younger adults from severe RSV illness, supported by data presented to the CDC’s Advisory Committee on Immunization Practices (ACIP) in April 2025. Ongoing studies continue to assess vaccine efficacy and durability across different populations.

HHS Secretary RFK Jr Replaces CDC Vaccine Advisory Panel With New Appointees

Health and Human Services Secretary Robert F. Kennedy Jr. removed all 17 members of the CDC’s Advisory Committee on Immunization Practices (ACIP) and appointed eight new members, some with controversial ties to vaccine skepticism and misinformation. This decision prompted widespread concern from medical organizations, including the American Medical Association (AMA), which called for a Senate investigation and urged Kennedy to reverse the action. The administration stated the changes aimed to restore public trust and reduce conflicts of interest, but public health leaders fear the impact on vaccine policy and independent scientific guidance.

Merck’s Clesrovimab (Enflonsia) Receives FDA Approval to Protect Infants from RSV During First Season

The FDA has approved Merck’s clesrovimab (Enflonsia), a long-acting monoclonal antibody for passive immunization against respiratory syncytial virus (RSV) in infants during their first RSV season. This single-dose treatment demonstrated a 60.5% reduction in medically attended RSV lower respiratory infections and an 84.3% reduction in RSV-related hospitalizations in the phase 2b/3 CLEVER trial. Enflonsia is expected to be available for the 2025-26 RSV season, providing a new preventive option for both healthy and high-risk infants, supported by additional data from the ongoing phase 3 SMART trial comparing its safety and efficacy with palivizumab.

Novavax Reports Immune Responses and Safety in Phase 3 Trial of COVID-19-Influenza Combination Vaccine

Novavax reported initial phase 3 results showing that its COVID-19–influenza combination vaccine (CIC) and a stand-alone trivalent influenza vaccine candidate (tNIV) generated neutralizing antibody responses comparable to licensed vaccines in adults aged 65 and older, with over 98% of adverse events being mild or moderate and no new safety concerns identified. The descriptive study assessed immunogenicity against influenza strains H1N1, H3N2, B, and SARS-CoV-2, supporting future registrational trial design. These findings build on prior phase 2 data demonstrating strong immune responses and safety. Additionally, interim data from a phase 2/3 study of an updated COVID-19 vaccine targeting Omicron XBB.1.5 showed significantly improved immune responses, highlighting booster potential.

The Lingering Threat: Managing Severe COVID-19 in the Post-Pandemic Era

Despite declining COVID-19 cases and deaths globally, severe COVID-19 remains a significant concern, especially in critical care, due to low vaccination rates and the potential emergence of new variants. Current management follows established ARDS protocols, with remdesivir as the primary antiviral for hospitalized patients needing oxygen, alongside dexamethasone and selective immunomodulators (IL-6 and JAK inhibitors) for severe cases. The WHO classifies variants into monitoring categories, with no active variants of concern as of late 2024. Diagnostic focus is on nucleic acid testing, while antibody therapies and convalescent plasma are generally not recommended for hospitalized patients. Treatment guidelines continue to evolve, guided by societies like IDSA and WHO after the NIH panel’s dissolution in 2024.