COVID-19 Vaccines: Did Research Exclusion Affect Informed Consent?

Thomas Milovac looks back at the groups initially excluded from COVID-19 vaccine research, such as pregnant and breast-feeding women, and considers whether their exclusion prevented members of these groups from being able to provide informed consent to vaccination.


The COVID-19 pandemic required scientists, governments, and industry to move quickly – maybe even at the “speed of science” to study and manufacture vaccines. Although science and medicine moved at a rapid pace, the empirical trials exhibited that the vaccines were highly efficacious. However, certain groups were excluded from trial participation, and this meant that data regarding the safety and efficacy of the vaccines on these groups were not available when the vaccines came on the market. In particular, pregnant and breast-feeding women were excluded from trial participation, something Harriette Van Spall refers to as “protection by exclusion”. When such exclusion occurs, estimates and anecdotal reports by medical practitioners must fill in for clinical trial data.

Research conducted since the initial rollout of vaccines shows that COVID-19 vaccination during pregnancy does not differentially impact pregnant women or perinatal outcomes when compared to unvaccinated women. Nevertheless, their exclusion from the initial trials ought to be startling because studies at the time showed that pregnant women were at a heightened risk of negative outcomes due to COVID-19.

Photo Credit: Pixabay. Image Description: COVID-19 vaccine vials, a syringe and a mask are kept together.

Despite their exclusion during the trial stage, pregnant and breast-feeding women were permitted to receive the vaccines in order to protect them from severe outcomes, but what can ethically be made of their consent to vaccination? In other words, because this group was excluded from trial participation no data pertaining to them was available at the time of vaccination and that ought to have called into question whether these women could have actually expressed informed consent when they lacked relevant information.

For example, we can turn to Ontario’s Health Care Consent Act, to look more closely at consent. Accordingly, consent provided for treatment needs to be: related “to the treatment,” “informed,” voluntary, and not “obtained through misrepresentation”. For consent to be rightfully deemed informed the patient needs to have received information pertaining to: “the nature of treatment,” “expected benefits,” “material risks,” “material side effects,” “alternative courses of action,” and “the likely consequences of” foregoing treatment. Were these legal and ethical criteria met in the case of pregnant and breast-feeding women?

It is hard to see how the benefits, risks, and side effects of treatment would have been reasonably known or how health care providers could have answered questions pertaining to such inquiries. Pregnant and breast-feeding women present physiologically unique characteristics such as lactation and pregnancy that differ fundamentally from those participants included in the trials. Pharmacokinetic research shows that the physiological changes that accompany pregnancy do impact the way in which the body responds to medications. Because of this very real difference it is reasonable to think that vaccination may likewise present different challenges to this group of individuals.

The benefits, risks, and side effects could not have been demonstrated for pregnant and breast-feeding women because there were no such individuals in the trials from which that data could have been collected. In order to inform a pregnant or breast-feeding patient regarding the benefits, risks, and side effects, the scientific record needed to contain evidence specific to such individuals – but it did not.

Furthermore, the exclusion of pregnant and breast-feeding women from these trials fails to support the practice of evidence-based medicine and patient-centered care. The former holds that physicians ought to rely on the ever-growing body of scientific literature to inform their practice. The latter holds that care provided to patients ought to be centered around their particular needs. If there was no evidence regarding the benefits and risks of vaccination of pregnant or breast-feeding women, then how could the provision of vaccines to them have been “evidence-based”? And, if patients are to be cared for based on their unique characteristics and context, then how is it patient-centered to assume empirical evidence derived from other groups is sufficient to be generalized to the particular group excluded from participation?

It ought to be seriously questioned why the absence of pregnant and breast-feeding women from COVID-19 vaccine trials was not deemed, at the very least, an obstacle to consent. Informed consent does not mean something like “full knowledge”. But information relevant to one’s particular physiological state is significant for being informed. Using Ontario’s Health Care Consent Act as an example, evidence pertaining to the specific group under consideration is necessary because only when the specific group is studied can the risks, benefits, and side effects be properly communicated to group members. Health care ought to strive toward being evidence-based and patient-centered, two elements of care that are precluded when scientific evidence is not readily forthcoming with respect to the particular physiological state of one’s patient.


Thomas Milovac is a doctoral candidate at the University of Waterloo.

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