Studies and Research
The body of research on the effects of intramuscular injections is vast and detailed. However, the highly technical language in these studies can be difficult for the general public to understand.
In public health research, authors often soften their wording due to pressure from journals to downplay negative findings on side effects and adverse reactions. As a result, important insights are frequently obscured or carefully phrased in the papers themselves—though they remain visible in the data sets and discussion sections upon close review.
To address this, HFDF has created this searchable compendium of studies, each paired with clear, plain-language summaries and notes prepared by our team. Our goal is to cut through technical complexity, bias, and ambiguity so individuals can access the key facts and make informed health decisions.
This resource will continue to grow, with new studies and improvements added regularly.
Please note that HFDF does not necessarily endorse or support any policy arguments or specific assumptions made by the authors. HFDF commentary describes and summarizes the role this study plays in the scientific discourse and provides abbreviated notes.
Recently Posted Studies
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COVID-19 Vaccine-Induced Subclinical Myopericarditis: Pathophysiology, Diagnosis, and Clinical Management
Journal: THE EUROPEAN SOCIETY OF MEDICINELead Author:
McCullough, et al.Original date of publication:
11/30/2025This paper explores the phenomenon of subclinical myopericarditis and heart injury quietly occuring before symptoms, with sudden cardiac arrest as the first sign of disease in some cases.
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The Introduction of Diphtheria-Tetanus-Pertussis and Oral Polio Vaccine Among Young Infants in an Urban African Community: A Natural Experiment
This paper shows that infant (under 1 year old) mortality is 10 times higher after DTP vaccination vs those who have not received it.
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Serial Vaccination and the Antigenic Distance Hypothesis: Effects on Influenza Vaccine Effectiveness During A(H3N2) Epidemics in Canada, 2010-2011 to 2014-2015
The antigenic distance hypothesis (ADH) is explored in this research, suggesting that closer strains in the shots generate better outcomes for flu vaccination.
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Interim estimates of 2014/15 vaccine effectiveness against influenza A(H3N2) from Canada’s Sentinel Physician Surveillance Network, January 2015
The researchers in Canada found negative efficacy for the 2014/2015 vaccine campaign against flu. Those kids who got the shots had more medically-attended flu.
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Infectious virus in exhaled breath of symptomatic
Journal: Proc Natl Acad Sci U S ALead Author:
Yan J, et al.Original date of publication:
01/30/2018This study found that people vaccinated against flu two seasons consecutively were 6 tumes more contagious than unvaccinated people








