New & updated
1. Hepatitis B vaccine trial in Guinea-Bissau
A Dec. 18, 2025, Federal Register notice announced that CDC had awarded a $1.6 million, single-source grant to the University of Southern Denmark to study the hepatitis B vaccine in the West African nation of Guinea-Bissau. The grant went to Christine Stabell Benn and Peter Aaby, two researchers frequently cited by HHS Secretary Robert F. Kennedy, Jr., for a widely criticized study in Guinea-Bissau that claimed to have found that DPT and OPV vaccines were associated with five-fold increased mortality by the age of 6 months.
As we shared in December, CDC recommended that the United States shift from universal hepatitis B vaccination at birth to a practice where those testing negative would be vaccinated no sooner than two months of age. This study intends to take advantage of a planned change by Guinea-Bissau in the opposite direction: The country will start giving universal birth doses of the hepatitis B vaccine in 2027, as recommended by the World Health Organization. (Currently, infants in Guinea-Bissau receive the vaccine six weeks after birth.) Until that occurs, the researchers want to conduct a randomized, controlled trial comparing the current approach in Guinea-Bissau to the new one.
The design of the proposed study has major flaws. Despite prevalence rates of hepatitis B in Guinea-Bissau estimated at 18%, not all pregnant women are tested for hepatitis B, and some infected mothers will falsely test negative. These mothers are at high risk for transmitting hepatitis B to their infants, yet the study would leave half these infants unprotected.
In addition, the study will measure only short-term effects of the vaccine, of which there are likely to be at least some, which will make giving the vaccine at birth appear worse, at least until the 6-week dose is administered to the comparison group. But longer-term outcomes, such as whether one group is more likely to contract hepatitis B infection, are not slated to be measured. These outcomes, if they were to be collected, are thought likely to establish the birth dose as more effective at protecting infants.
For these and other reasons, the study has caused an uproar. At this point, despite continued pressure from the US government, it appears that the study is not proceeding.
Editors’ Note: It is a bedrock principle of research ethics that a study cannot deny the standard of care to patients, and the World Health Organization recommendations can be considered the standard of care. If this study fails to provide a proven vaccine in the most effective manner to prevent hepatitis B, it would be a gross violation of human rights.
2. US conditions GAVI funding
In June 2025, Sec. Kennedy announced that the US government was withholding funding from Gavi, an international organization that aims to increase access to vaccines in poor countries, accusing Gavi of not taking vaccine safety seriously. In January 2026, it was reported that the US has asked Gavi to develop a plan to remove thimerosal from vaccines as a condition for restarting funding. Thimerosal is a preservative used in multi-dose vials of vaccines to ensure that the vaccines do not become contaminated each time a syringe enters the vial. Multi-dose vials are common in lower-resourced countries that may lack the refrigeration to store single-dose vials. A CDC review of available evidence that was briefly posted online in advance of the June 2025 ACIP meeting (and then taken down on orders of political appointees) concluded that prenatal exposure to thimerosal did not cause autism or other neurodevelopmental delays.
Editors’ note: The demand by the US government that Gavi phase out thimerosal-containing vaccines will not improve the health of the children Gavi serves. Instead, it will make it more difficult for those kids to access the very vaccines that protect them from serious illness and death because thimerosal-free versions are not widely available.
3. Sec. Kennedy overhauls the Interagency Autism Coordinating Committee (IACC)
In a move reminiscent of what he did with the Advisory Committee on Immunization Practices, Sec. Kennedy has replaced all 21 members of the IACC. This committee, which is housed at NIH and was statutorily created by Congress, develops recommendations for autism research. Many of the new members are proponents of the disproven theory that vaccines cause autism. The Autism Science Foundation criticized the move saying that the new committee has a “striking absence of scientific expertise” and fails to represent the broader autism community.
Editors’ note: Sec. Kennedy is taking over yet another federal advisory committee without a meaningful process or justification. Vital autism research funds may be diverted from worthier research projects as a result.
4. CDC stops publishing public databases related to vaccines
In January 2026, researchers found that CDC had stopped updating many public databases, most of which were related to vaccines and outcomes related to vaccines. The article, published in the Annals of Internal Medicine, found that 38 of the 82 databases that had previously been updated regularly were now no longer current.
Examples of databases that were no longer up to date include those on weekly vaccination rates for pregnant women, vaccination rates for US adults (with geographic and demographic breakdowns), and respiratory illnesses treated in emergency departments (some of which can be prevented by vaccines).
Editors’ note: These changes, along with others we have highlighted previously, hinder the ability of scientists and the public to document and understand the public health implications of the changes to vaccine policy that are currently underway.
