Interim estimates for how well this year's flu vaccines protected against medically attended flulike illness showed moderate vaccine effectiveness (VE) overall, with higher levels in children than in adults, researchers from the Centers for Disease Control and Prevention (CDC) and their state health partners reported today in the latest edition of Morbidity and Mortality Weekly Report (MMWR).

The data come from four networks that the CDC uses to track vaccine effectiveness, which cover patients in 22 states. This is the first year that pediatric and adult VE estimates from the four networks have been presented together. The study did not measure how VE waned after vaccination.

For adults, VE against flu diagnosed in outpatient settings ranged from 33% to 49% and against flu hospitalization ranged from 41% to 44%. For the pediatric age-group, VE for flu detected in outpatient settings was 59% to 67% and against flu-linked hospitalization was 52% to 61%. "These findings demonstrate that the 2023–24 seasonal influenza vaccine is effective at reducing the risk for medically attended influenza virus infection," the group wrote, noting that the interim results were consistent with findings from previous years.

The vaccines were effective against both influenza A, which has mainly been the 2009 H1N1 strain this season, and influenza B, similar to recent estimates from Canada and Europe. For seniors, a group at higher risk for flu complications, VE was similar to adults ages 18 to 64 years old.

The CDC noted that flu vaccine coverage has been lower this season than last season and is even lower than prepandemic uptake.

California estimate also finds moderate protection

In a separate report in the same MMWR issue, an analysis of surveillance data from California found that flu vaccines so far this season have provided moderate protection against lab-confirmed flu across all age-groups.

Overall, VE was 45%, highest in children younger than 18 years old. VE declined with age and was 30% in adults ages 65 and older.

Pfizer today announced that its respiratory syncytial virus (RSV) vaccine Abrysvo maintained high efficacy in the second season after vaccination in adults ages 60 and older, according to the latest data from an ongoing phase 3 clinical trial.

In a press release, the company said vaccine efficacy against RSV-related lower respiratory tract disease, defined by three or more symptoms, after season two was 77.8% (95.0% confidence interval [CI], 51.4% to 91.1%). For comparison, vaccine efficacy after season one was 88.9% (95% CI, 53.6% to 98.7%).

Efficacy was consistent across the seasons for both RSV A and RSV B strains. Researchers also saw sustained efficacy against less severe symptoms: 65.1% after season one and 55.7% after season two. No new adverse events were reported through the second season.

Durable protection against 2 strains

Annaliesa Anderson, PhD, senior vice president and chief scientific officer of vaccine research and development at Pfizer, said the company is encouraged by the level of protection after two full RSV seasons. "This new data indicate that broad and durable protection against both types of RSV that cause disease, RSV A and RSV B, is the potential benefit to having a bivalent vaccine."

Broad and durable protection against both types of RSV that cause disease, RSV A and RSV B, is the potential benefit to having a bivalent vaccine.

The company said it will submit the data to regulatory authorities and vaccine technical committees and will publish the findings in a peer-reviewed scientific journal.

In the United States, the Food and Drug Administration (FDA) approved Abrysvo for people ages 60 and older in May 2023, and the following month the Centers for Disease Control and Prevention recommended Abrysvo and the RSV vaccine made by GSK (Arexvy) for adults ages 60 and older based on shared clinical decision making with health providers. In September, the CDC recommended that pregnant women receive Abrysvo as a strategy to protect newborns from RSV.

Patients undergoing gastrointestinal surgery at safety net hospitals are at increased risk of surgical-site infections (SSIs), according to a research letter yesterday in JAMA Surgery.

Using data from the Nationwide Readmissions Database for, researchers from Memorial Regions Hospital in Florida assessed SSIs identified during initial admission or readmission within 90 days of gastrointestinal surgery from 2019 to 2020. Safety net hospitals were identified as publicly funded, metropolitan teaching, and large by number of beds per US region. To account for risk factors such as age, comorbidities, low household income, and lack of insurance, the researchers performed a propensity score matching analysis.

30% increased risk in safety net hospitals

Of the 392,368 patients identified, 23,447 (6.0%) were treated at safety net hospitals (mean age 52.4 years, 50.2% female). The overall SSI rate was 3.0%, of which 59.2% of infections were found during readmission, but the rate in safety net hospitals was 7.8%.

After propensity score matching, the overall SSI rate was 3.5%, and SSI risk was increased by nearly 30% in safety net hospitals (odds ratio, 1.29; 95% confidence interval, 1.16 to 1.42). SSI risk was higher at safety net hospitals for all sites (eg, superficial incisional, deep incisional, organ space).

The findings are noteworthy because the Centers for Medicare and Medicaid Services (CMS) has imposed financial penalties on hospitals that have high rates of healthcare-associated infections since 2014, and those penalties to date have proven ineffective at reducing infection rates at safety net hospitals. Although CMS made adjustments to hospital penalties for readmissions in 2019 to account for the socioeconomic differences among patients treated at safety net hospitals, the study authors say their findings indicate similar adjustments are needed for SSIs.