Reframing vaccine safety: recognizing mass psychogenic illness as an adverse event following immunization

Diagnoses of mass psychogenic illness (MPI) following vaccination usually occur after the failure of all efforts to find a plausible biological mechanism for the collective reaction to the vaccine in question. They are experienced as waste-basket diagnoses that leave sufferers feeling dissatisfied and neglected, without appropriate treatment or sympathy and without a “real” diagnosis. In this article, we examine reports of MPI following vaccination, focusing on vaccination programs against human papillomavirus (HPV), which usually target adolescent and preadolescent girls, as well as social science research that tries to explain the social factors involved.

In particular, we interrogate social science research that aligns with participants’ feelings that they are being dismissed because MPIs are not perceived to be real illnesses. Our analysis of the scholarly literature finds that relying on debunking strategies contributes to limitations in social science responses to instances of MPI following vaccination. Recognizing MPI reactions as plausible adverse reactions to vaccination, we argue, could lead to successful treatments and changes to vaccination programs, both of which could bolster trust in vaccination, as long as the diagnosis is not used to dismiss or diminish psychogenic adverse reactions.

As part of this process, the informational and communicative context is crucial to addressing vaccinee suffering and improving public trust. Concerns about vaccine side effects are as old as vaccines (Durbach, 2005) but have crescendoed since the COVID-19 pandemic. Prior to COVID, contestations about adverse reactions animated many vaccine debates, including MMR (measles, mumps, and rubella), pertussis, and HPV (human papillomavirus) vaccines in particular, leading to redesigned vaccines (e.g., acellular pertussis in the 1990s), numerous studies to rule out causal links between vaccines and conditions like autism, and, in at least one country, removal of the vaccine from official recommendations (HPV in Japan).

During COVID, the urgent and successful development of vaccines facilitated pandemic control yet “laid the foundation for what is now an emboldened anti-vaccine movement and increased vaccine hesitancy,” due in part to ever-changing public health communication about pandemic prophylaxis and increasing societal distrust (Ortiz-Prado et al., 2025). Post-pandemic, increasing pockets of unvaccinated children around the world have led to spikes in measles, reflecting the real-world consequences of growing concerns about vaccine adverse effects, often related to political mistrust (Ewe, 2026; Michaud, 2026). Public health officials are concerned that proliferating beliefs about deleterious vaccine side effects will threaten the stability and effectiveness of vaccination programs.

Yet not acknowledging vaccine side effects also constitutes a threat, because lack of recognition of people’s felt experience may threaten public confidence in vaccines and trust in the health professionals who recommend and administer them (WHO, 2017). In this way, fears of derailing vaccination programs collide with fears of damaging personal health. Embedded in this conflict is the question of what constitutes a side effect caused by a vaccine or the vaccination process, as well as who gets to decide what that is and how to treat it.

In this paper, we tackle these questions by looking at a specific subset of adverse events following immunization (AEFIs)Footnote 1—mass psychogenic illness (MPI)—with respect to a vaccine against a specific viral agent—HPV. As part of this analysis, we identify and analyze a specific trend in the social science literature: one that sees the MPI diagnosis as suspicious and delegitimizing of the vaccinees’ suffering. We seek to understand why some social scientists approach MPI events—whether in response to vaccination or in other contexts—by manifesting skepticism of the diagnosis itself and suggesting another, usually explicitly organic, cause.