The 2024-2025 COVID-19 Vaccines Show Limited Efficacy in Adults
The interim results demonstrated a slightly better vaccine effectiveness in individuals who are immunocompetent vs immunocompromised individuals.
cdc logo: Image credit: CDC
In this week’s Centers for Disease Control’s (CDC) Morbidity and Mortality Weekly Report, data show limited efficacy in preventing emergency department visits for adults and a better efficacy in immunocompromised adults.
“Vaccine effectiveness (VE) of 2024–2025 COVID-19 vaccine was 33% against COVID-19–associated emergency department (ED) or urgent care (UC) visits among adults aged ≥18 years and 45%–46% against hospitalizations among immunocompetent adults aged ≥65 years, compared with not receiving a 2024–2025 vaccine dose. VE against hospitalizations in immunocompromised adults aged ≥65 years was 40%,” the authors wrote.
Last year, the CDC’s Advisory Committee on Immunization Practices (ACIP) recommended 2024–2025 COVID-19 vaccination with an FDA-authorized or approved vaccine for all persons aged 6 months or older. Subsequently, the FDA approved monovalent 2024–2025 COVID-19 vaccines by Moderna and Pfizer-BioNTech and authorized a monovalent 2024–2025 COVID-19 vaccine by Novavax for persons aged 12 years of age and older.
ACIP recommended a second vaccine dose for all adults aged ≥65 years and for persons aged 6 months–64 years who were moderately or severely immunocompromised and were 6 months removed from their last dose of the 2024–2025 COVID-19 vaccine. Additionally, ACIP recommended that persons aged ≥6 months who are moderately or severely immunocompromised may receive additional doses of 2024–2025 COVID-19 vaccine.
Vaccine Analysis
The analysis was conducted through 2 groups: the Virtual SARS-CoV-2, Influenza, and Other Respiratory Viruses Network (VISION), and the Investigating Respiratory Viruses in the Acutely Ill (IVY) Network.
VISION is a multisite electronic health care records (EHR)–based network that encompasses 373 ED/UCs and 241 hospitals across 8 states. Eligible patients are those who have received molecular or antigen testing for SARS-CoV-2 during the 10 days preceding, or ≤72 hours after, an eligible ED/UC encounter or hospital admission. COVID-19 vaccination history is ascertained from state or jurisdictional registries, EHRs, and, in a subset of sites, medical claims data.
The IVY network consists of 26 hospitals in 20 states. They enroll adults aged ≥18 years with COVID-19–like illness† who also receive molecular or antigen testing for SARS-CoV-2 within 10 days of illness onset and within 3 days of hospital admission.
The investigators point out that individuals who received the latest vaccine ≥7 days before the encounter index date (VISION) or illness onset date (IVY) were considered vaccinated. Conversely, those who had not received the 2024-2025 vaccine—regardless of previous COVID-19 vaccination or infection history—were considered not vaccinated and served as comparators.
Vaccine effectiveness of the 2024-2025 COVID-19 Vaccine
Image credit: CHATgpt
Other Study Considerations
The investigators point out that COVID-19–associated hospitalizations were relatively low compared with those during previous years, precluding estimation of vaccine efficacy against critical illness such as admission to the intensive care unit, invasive mechanical ventilation, or death. They explained that VE against these outcomes has been higher and more sustained than that against less severe outcomes in past years.
With both lower hospitalization and vaccination rates, vaccine effectiveness could not be estimated for children and adolescents between the ages of 5–17 years for either outcome, and for adults aged 18–64 years against hospitalization.
Despite the aforementioned study limitations and these lower VE rates, the investigators do see some protection afforded as a positive benefit.
“In this analysis, receipt of a 2024–2025 COVID-19 vaccine dose provided additional protection against COVID-19–associated ED/UC visits and hospitalization among adults with and without immunocompromise. These results support CDC and ACIP recommendations for 2024–2025 COVID-19 vaccination,” they wrote.
