Pediatrics Expert’s Opinion Regarding a Target 95% Vaccination Rate Met the Daubert Bar
Posted on March 11, 2025 by Expert Witness Profiler
On July 22, 2022, Dr. Gregory Fox, individually and as parent of C.F., and Rita Fox, individually and as parent of C.F. (jointly, the Plaintiffs), filed a lawsuit challenging the state of Maine’s public school vaccination requirements.
Dr. Laura Blaisdell, a pediatrician with extensive qualifications in medicine and public health, was presented as an expert witness by Department of Education Commissioner Pender Makin. Fox’s challenge centered on Blaisdell’s opinion regarding a 95% vaccination rate target. He argued that her reliance on the R0 variable, which assumes a “totally susceptible” population, was unreliable and unsupported by scientific methodology when applied to the case’s specific facts. He claimed her assumption was erroneous because the population in question was only “partially susceptible”.
Furthermore, Fox contested the scientific support for the 95% vaccination coverage goal, asserting that Blaisdell erred in inferring its necessity to protect susceptible individuals or halt disease transmission.
Pediatrics Expert Witness
Laura L. Blaisdell, MD, MPH, FAAP, CPE is a board-certified pediatrician, public health consultant, and researcher with expertise in vaccine hesitancy, infectious disease control, and camp medicine. She holds a Doctor of Medicine (MD) from the University of Minnesota Medical School and a Master of Public Health (MPH) from the University of Minnesota School of Public Health. She is also a Certified Physician Executive (CPE) and a Fellow of the American Academy of Pediatrics (FAAP).
Blaisdell has served as an Attending Physician in the Department of Pediatrics at Maine Medical Center since 2008 and is an Assistant Professor at Tufts University School of Medicine. Her research and clinical work focus on vaccine decision-making, public health policy, and disease prevention in communal settings, particularly youth camps. She has been a key figure in vaccine advocacy and has contributed to legislative efforts to promote immunization policies.
Discussion by the Court
Commissioner Makin countered that Fox conflated herd immunity threshold rates with public health vaccination targets for schools. They argued that Blaisdell’s use of R0 was a generally accepted practice for determining herd immunity thresholds.
Regarding the 95% target, the Commissioner emphasized that it was a public health goal, not a herd immunity threshold, aligning with targets set by the United States Centers for Disease Control and Prevention (U.S. CDC) and the Maine Center for Disease Control and Prevention (Maine CDC). Blaisdell, in her deposition, clarified the distinction, stating that the 95% figure represents a public health recommendation for school vaccination levels.
Analysis
The Court acknowledged that Blaisdell’s use of R0 to calculate herd immunity thresholds was supported by scientific literature, including articles cited by both parties. While the use of this methodology in other scientific literature is not conclusive, it did demonstrate a measure of acceptance within the scientific community.
The Court ruled that Fox’s challenge regarding the “partially susceptible” population goes to the weight and credibility of Blaisdell’s testimony, not its admissibility. The Court also recognized the distinction between herd immunity thresholds and public health vaccination goals.
Blaisdell’s reliance on sources like the CDC and state health reports, as well as her clear explanation during deposition, provided sufficient support for the 95% target as a public health goal. Moreover, Blaisdell sufficiently distinguished herd immunity threshold calculations from the public health goal of 95% vaccination coverage. Therefore, challenges to the weight and credibility of the 95% goal did not prevent the testimony from being admissible.
Held
The Court dismissed without prejudice Gregory Fox’s motion to partially exclude the testimony of Dr. Laura Blaisdell.
Key Takeaway:
This case highlights the importance of distinguishing between different types of scientific targets, such as herd immunity thresholds and public health goals. It also demonstrates the Court’s role in evaluating the reliability and relevance of expert testimony under the Daubert standard. The Court’s decision emphasizes that challenges to the factual underpinnings of expert opinions primarily affect their weight and credibility, not necessarily their admissibility.
Case Details:
| Case Caption: | Fox Et Al V. Makin Et Al |
| Docket Number: | 2:22cv251 |
| Court: | United States District Court, Maine |
| Order Date: | March 10, 2025 |
