Examining Aaron Siri’s Claims on Flu Vaccines for Pregnant Women
Originally published: 2025-10-28
Attorney Aaron Siri has brought attention to a significant issue regarding the regulatory basis for influenza vaccines in pregnant women. Through a Freedom of Information Act (FOIA) request, Siri and the Informed Consent Action Network (ICAN) sought evidence of clinical trials used to license flu shots specifically for this group. The FDA’s response revealed a notable gap, prompting concerns about the foundation of current practices. This post focuses on Siri’s claims and the questions they raise about transparency in vaccine licensing.
“We FOIA’ed the FDA w/ a simple request. Provide all the clinical trials relied upon to license the flu shot for pregnant women ... They finally admitted we don’t have any clinical trials because it’s never been licensed for pregnant women.”
— Aaron Siri
The Basis of Siri’s Claim
Siri’s assertion originates from a 2018 FOIA request filed by his firm on behalf of ICAN. The request asked for copies of clinical trial reports that the FDA relied upon to license any influenza vaccine (or Tdap vaccine) for indicated use in pregnant women. The FDA’s eventual response indicated that no such dedicated trials existed for the licensing process, as the vaccines were not approved based on studies specifically enrolling pregnant participants.
This highlights Siri’s concern that flu vaccines have not been formally licensed for pregnant women, despite their widespread use in this population. The absence of pre-licensure trials tailored to pregnant women underscores questions about how approvals are granted without direct evidence from the intended group.
FDA’s Response and Licensing Practices
In a November 9, 2018, letter, the FDA stated it had no responsive records because clinical studies for influenza vaccines “did not specifically enroll pregnant women.” These vaccines are licensed for general age groups, such as adults 18 and older, which may include pregnant individuals, but without a specific indication for pregnancy. Siri points out that this means the vaccines are not officially licensed for pregnant women, raising issues about informed consent and regulatory standards.
The FDA’s approach relies on data from non-pregnant populations for initial licensing, with additional information gathered post-approval. This framework, according to Siri, may not adequately address the unique considerations for pregnant women, fueling debates on whether such practices sufficiently prioritize safety data from relevant trials.
“Clinical studies for these vaccines did not specifically enroll pregnant women.”
— FDA Response to ICAN FOIA Request, 2018
Updates in Vaccine Labeling and Ongoing Concerns
A recent case involves Flublok, a recombinant influenza vaccine, whose label was updated in October 2024 to include data from a post-licensure observational study of over 48,000 pregnant individuals. This update adds information to the pregnancy section but does not change the vaccine’s general indication or introduce pre-licensure trial data from pregnant women. Siri and ICAN have used such examples to emphasize that licensing continues without dedicated pre-approval studies, questioning the reliance on after-the-fact data.
No influenza vaccine is FDA-approved specifically for use during pregnancy, approvals cover broader categories. This persists as a core concern in Siri’s advocacy, highlighting potential gaps in the evidence base for this demographic.
Broader Implications and Questions Raised
Siri’s claims spotlight issues of transparency and the need for more rigorous data in vaccine licensing for vulnerable groups like pregnant women. The FDA’s admission via FOIA suggests that decisions may be made without clinical trials directly assessing the population in question, prompting calls for greater accountability. For those concerned, this underscores the importance of scrutinizing regulatory processes and seeking detailed information on how approvals are determined.
“No influenza vaccine is approved by the FDA specifically for use during pregnancy; indications are for general age groups.”
— Summary of FDA Practices
In summary, Aaron Siri’s FOIA findings reveal a lack of specific clinical trials for licensing flu vaccines in pregnant women, aligning with his concerns about the regulatory framework. This situation invites further examination of how such practices impact informed decision-making in healthcare.
