US lawmakers have sent a letter to federal health officials demanding answers on how and why a controversial vaccine trial in West Africa received federal funding.

The letter from Democratic members of the House Energy & Commerce Committee to Centers for Disease Control and Prevention (CDC) Acting Director Jim O’Neill asks for all documentation regarding the decision to award a five-year, $1.6 million grant to a team of Danish researchers conducting the study, which aims to assess the overall health impact of the hepatitis B vaccine birth dose in Guinea-Bissau. Half of the estimated 14,000 newborns enrolled in the randomized controlled trial will not receive the birth dose of the vaccine.

CIDRAP News first reported on the study in December, shortly after it was announced in the Federal Register. The trial has been widely criticized as unethical, given the known efficacy of a birth dose of the hepatitis B vaccine and the high prevalence of chronic hepatitis B infection in Guinea-Bissau. 

“Without the vaccine, as many as nine in ten infants could develop chronic infection that can lead to liver failure and death,” ranking committee members Frank Pallone (D-NJ), Diane DeGette (D-CO), and Yvette Clark (D-NY), wrote to O’Neill. “In that context, deliberately withholding a proven vaccine that has saved millions of lives globally for the sole purpose of examining theoretical, non-specific side effects may constitute a major breach of scientific ethics. And using taxpayer dollars in such a study rather than using those dollars to provide proven, life-saving vaccinations to babies is abhorrent.”

Trial’s status in question

Critics have also questioned the trial’s protocol, the track record of the researchers conducting the study, and why the CDC awarded the grant without the usual competitive process. The questions raised about the trial led the government of Guinea-Bissau to temporarily suspend it pending further review, although US officials maintain it’s going forward as planned.

The letter asks O’Neill to clarify the status of the trial, produce all versions of the study proposal and protocol, describe the CDC’s communications and coordination with Guinea-Bissau’s Ministry of Health, and provide any documentation regarding the decision to award the grant without a competitive process. 

The most recent FluView report from the Centers for Disease Control and Prevention (CDC) shows an additional eight pediatric deaths last week, raising the season’s total to 60 pediatric deaths from flu complications. Approximately 90% of the 60 children were not fully vaccinated against influenza. 

The CDC estimates there have been at least 22,000,000 illnesses, 280,000 hospitalizations, and 12,000 deaths from flu so far this season.

There was a downward trend in provider visits for influenza-like illness (ILI), to 4.4% above the national baseline. Overall, the positivity rate for influenza detections in clinical labs remained steady at 18.0%, and the cumulative hospitalization rate is 63.2 per 100,000 population. 

Seasonal influenza activity remains elevated nationally.

“Seasonal influenza activity remains elevated nationally. Most areas of the country are reporting stable or decreasing trends in activity; however, activity continues to increase in HHS Region 10 (Pacific Northwest),” the CDC said. 

Increasing influenza B activity

As has been typical in other flu seasons, influenza A activity is decreasing while influenza B is increasing. For week 4 of 2026 surveillance data, influenza A was detected in 76.9% of samples, while influenza B was detected in 23.1% of samples. 

For the total 2025-26 flu season, 92% of flu specimens have been typed as influenza A. Among 822 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at the CDC, 91.5% belonged to subclade K, a variant that has mutated to evade immunity from the current flu vaccine strain.

Influenza vaccination is associated with significantly lower odds of myocardial infarction (MI), according to a large meta-analysis published late last week in BMC Public Health. 

In the study, researchers led by a team from Zhejiang Chinese Medical University in Hangzhou, China, gathered data from 15 observational studies, including seven cohort studies, seven case-control studies, and one self-controlled case series. Together, the studies involved 23.5 million people. Most participants were older adults, ranging from approximately 57 to 77 years.

In analyzing the pooled data, the researchers found flu vaccination was associated with an 18% reduction (range at the 95% confidence interval, 14% to 22%) in the odds of MI compared with unvaccinated controls. 

Consistent link across studies, patient groups

Subgroup analyses of the data found a consistent link between the flu vaccine and lower odds of heart attack across different types of studies and patient groups. When the team looked at age-stratified results, they found that vaccinated people 70 and older and those 70 and younger had comparably lower risk of heart attack. The same negative association held true for those who had previously had a heart attack compared with those who had not. The flu vaccine was associated with lower odds of MI in both cohort and case-control studies.

Heart attacks tend to be more common during flu season, note the authors, suggesting that viral infections may trigger systemic inflammation and raise the risk of cardiovascular events. 

“Influenza vaccination could potentially reduce the risk of MI by alleviating the systemic inflammation and endothelial dysfunction associated with infection,” the authors write. 

The analysis had some limitations. All included studies were observational and hence cannot establish causality, and flu vaccination was broadly defined, so information on the frequency and timing of vaccination was limited. 

Still, “this meta-analysis indicates that influenza vaccination is associated with lower odds of myocardial infarction,” write the authors, who called for future studies to “clarify the underlying mechanisms and to refine the understanding of this association in contemporary populations.”