Vaccines at the Crossroads:
The 'godfather of vaccines' is worried. Here's why | STAT
Vaccines at the Crossroads: A Century of Achievement Under Siege — and a New Frontier Against Cancer
BLUF — Bottom Line Up Front
Decades of vaccination have prevented an estimated 508 million cases of illness and one million deaths among American children born between 1994 and 2023. Yet in 2025 the United States recorded its worst measles year in over three decades — more than 2,200 cases across 45 states, with three fatalities — as federal vaccine policy was systematically dismantled under HHS Secretary Robert F. Kennedy Jr. Modeling published in JAMA (April 2025) projects that if childhood vaccination rates fall by just 10%, the country could see 11.1 million measles cases over the next 25 years. Simultaneously, mRNA technology — forged in the COVID-19 pandemic — is producing extraordinary early results against cancer: the individualized neoantigen vaccine mRNA-4157 combined with pembrolizumab cut melanoma recurrence risk by 44% in Phase 2b trials. The first commercial cancer vaccine approval is anticipated by 2027–2029. The field of vaccinology thus stands at a fateful juncture: conquering cancer while at risk of surrendering ground it took a century to gain.
The Architecture of Triumph
To understand what may be lost, it is necessary to understand what was built. The modern era of vaccinology began not in a pharmaceutical boardroom but in a series of mid-twentieth-century laboratories populated by scientists who had witnessed disease at its most lethal. The foundational figures — Stanley Plotkin, Maurice Hilleman, Jonas Salk, Albert Sabin, Hilary Koprowski — worked against a backdrop of epidemic polio seasons that closed public swimming pools, rubella outbreaks that caused tens of thousands of fetal deaths, and measles that killed children in hospital wards with regularity.
Stanley Plotkin, now 93, whose career has become a living chronicle of the field, developed or co-developed vaccines against rubella and rotavirus, and has edited the authoritative reference text Plotkin's Vaccines, now entering its ninth edition. His rubella work was driven directly by clinical experience: during the last major U.S. rubella outbreak in 1964–1965, approximately 11,000 women lost pregnancies to the infection and an estimated 20,000 babies were born with congenital rubella syndrome — deaf, blind, or cognitively impaired. Rubella vaccine was licensed in 1969, and between 2005 and 2018 only 15 American babies were born with congenital rubella syndrome.
Maurice Hilleman, who died in 2005, is credited with developing or substantially improving more than 40 vaccines and is considered by many historians of medicine to have saved more lives than any other scientist of the twentieth century. His work at Merck produced vaccines against measles, mumps, rubella, hepatitis A and B, chickenpox, meningitis, and pneumonia, among others. Hilary Koprowski, who died in 2013, developed an oral rabies vaccine and conducted early work on oral polio immunization. Jonas Salk's inactivated polio vaccine, introduced in 1955 following one of the largest clinical trials in history — involving 1.8 million children — reduced polio incidence in the United States by more than 96% within a decade.
The institutional architecture supporting these achievements was equally important. The Advisory Committee on Immunization Practices (ACIP), established by the U.S. Surgeon General in 1964, provided the scientific peer-review structure through which vaccine recommendations were evaluated and issued. The 1993 Vaccines for Children (VFC) program — created directly in response to a measles outbreak — gave low-income and uninsured children free access to the full schedule. Routine childhood immunizations from 1994 to 2023 are estimated to have prevented 508 million illnesses, 32 million hospitalizations, and one million deaths, according to CDC data published in the Morbidity and Mortality Weekly Report in 2024.
How Vaccine Targets Are Selected: From Pathogen to Antigen
The process of selecting a vaccine target is among the most intellectually demanding in all of biomedical science. The central challenge is identifying, from among the thousands of proteins a pathogen produces, the handful that will train the immune system to mount a durable and protective — rather than merely reactive or self-injurious — response.
Classical vaccinology proceeded empirically: researchers grew pathogens, attenuated or inactivated them, administered them to animals, and measured immune responses. This process worked, but it was slow and could not address pathogens that resisted culture or changed rapidly. The field was transformed by reverse vaccinology, an approach pioneered in the development of the meningococcal group B vaccine (MenB), in which the entire genome of a pathogen is sequenced and computationally screened for proteins likely to be surface-exposed, conserved across strains, and immunogenic. By starting from the genome rather than the whole organism, researchers can evaluate thousands of candidates in silico before committing resources to laboratory experiments.
Modern vaccine antigen selection now follows a structured five-stage workflow: target identification and prioritization using genomic and proteomic data; high-throughput screening of immunogenicity and specificity; structural and functional validation of shortlisted candidates; binding kinetics analysis; and selection for preclinical development. Tools such as VaxiJen (alignment-free antigen scoring), NetMHC (peptide-MHC binding affinity prediction), and the Immune Epitope Database (IEDB) allow researchers to rapidly rank candidates. Peptides with MHC binding affinities below 50 nM are typically considered strong binders and prioritized for further development.
Machine learning and deep learning are now transforming this process at every stage. A 2024 review in npj Vaccines described how algorithms are being applied to epitope identification, immunogen design, and prediction of antibody-antigen interactions. Protein structure prediction tools — most notably AlphaFold2 and AlphaFold3 — now allow three-dimensional antigen modeling for virtually any newly identified pathogen protein, enabling conformational epitope mapping that was previously impossible without crystal structures. Graph Neural Networks, as described in a 2025 npj Vaccines paper, outperform classical predictors on B-cell epitope identification, achieving precision-recall improvements of more than 44% over prior methods. AI is also being used to predict cross-variant immunity — a critical consideration for rapidly mutating viruses like SARS-CoV-2 and influenza — and to design immunogens that elicit broadly protective responses rather than strain-specific ones.
For pandemic preparedness, the WHO Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) demonstrated how real-time antigen selection operates at the international level: monitoring genetic and antigenic evolution of circulating variants, evaluating neutralizing antibody responses across populations, and advising manufacturers on reformulation timelines — a process requiring tight coordination of virological surveillance, immunological data, and manufacturing lead times.
The mRNA Revolution: From Pandemic Tool to Cancer Therapy
The most consequential development in vaccinology in the past two decades may not be any single vaccine but the maturation of mRNA technology. The foundational science — that synthetic messenger RNA could instruct human cells to produce a target protein and trigger an immune response — was developed over decades by researchers including Katalin Karikó and Drew Weissman at the University of Pennsylvania, who received the Nobel Prize in Physiology or Medicine in 2023 for their work on nucleoside modifications that made mRNA stable enough for clinical use. The COVID-19 pandemic forced this technology into mass application at unprecedented speed, generating a global body of manufacturing, safety, and immunogenicity data that has dramatically accelerated its extension into cancer.
The principle behind therapeutic cancer vaccines is conceptually elegant but technically demanding. Cancer cells harbor somatic mutations that produce abnormal proteins — neoantigens — not found in normal tissue. Because these are foreign to the immune system, they are potential targets. The challenge is that most tumors are genetically heterogeneous and their neoantigen profiles are unique to each patient. An mRNA cancer vaccine encodes a personalized set of neoantigens, directing the immune system to recognize and attack the tumor as if it were a pathogen. The process requires tumor sequencing, neoantigen prediction via algorithmic pipelines, rapid mRNA synthesis, and formulation into lipid nanoparticles for delivery — all against clinical timelines. As of 2024, this pipeline had been compressed from approximately nine weeks to under four weeks.
The most advanced clinical results to date come from mRNA-4157 (V940), developed by Moderna in collaboration with Merck. In the Phase 2b KEYNOTE-942 trial, published in The Lancet in 2024, mRNA-4157 combined with the PD-1 checkpoint inhibitor pembrolizumab produced a 44% reduction in melanoma recurrence risk compared with pembrolizumab alone in patients with resected high-risk disease. A three-year update presented at the American Society of Clinical Oncology in 2024 showed that the benefit was durable, with responding patients continuing to show significantly longer recurrence-free survival. The combination's mechanism illustrates the synergy of the approach: the vaccine primes T cells to recognize tumor neoantigens, while the checkpoint inhibitor removes molecular brakes that tumors use to suppress immune attack.
The pipeline has expanded far beyond melanoma. A 2025 review in Cancers (MDPI) identified over 120 active clinical trials of RNA-based cancer vaccines across malignancies including lung, breast, prostate, pancreatic, colorectal, and brain cancers. Results from a personalized neoantigen vaccine for pancreatic cancer, published by researchers at Memorial Sloan Kettering, showed vaccine-induced T-cell responses that were predictive of longer recurrence-free survival after a median follow-up of three years. At the American Association for Cancer Research Annual Meeting 2024, researchers reported promising Phase 1 data for TG4050, a vaccinia virus-based personalized vaccine for HPV-negative head and neck squamous cell carcinoma, where patients receiving the vaccine immediately after surgery showed early survival advantages over those receiving it only at relapse.
An equally significant development emerged from the University of Florida in 2025, where Elias Sayour and colleagues described a "generalized" mRNA vaccine that activated immune responses not by targeting specific neoantigens but by broadly reprogramming the immune system to fight as if confronting a viral infection. Published in Nature Biomedical Engineering, the study showed that this approach, combined with PD-1 inhibition, eliminated tumors in mouse models of melanoma, bone cancer, and glioblastoma. This concept — a non-personalized, "universal" immune activator that could potentially work across tumor types — would, if validated in humans, dramatically reduce manufacturing complexity and cost. Sayour's lab had previously reported the first human trial of a personalized mRNA glioblastoma vaccine that rapidly reprogrammed the immune system to attack tumor cells.
The LungVax program, backed by Cancer Research UK and the CRIS Cancer Foundation and developed jointly by the University of Oxford, University College London, and the Francis Crick Institute, represents a preventive approach: targeting early-stage cancer neoantigens in high-risk individuals (current or former heavy smokers aged 55–74) before cancer develops clinically. A trial of 3,000 participants is planned for 2026. In the United Kingdom, a personalized mRNA melanoma vaccine has reached Phase 3 trials and is expected to become the first therapeutic cancer vaccine offered through NHS clinics.
Despite this momentum, formidable challenges remain. Personalized vaccine manufacturing currently costs between $100,000 and $300,000 per patient and demands highly integrated clinical and manufacturing workflows. Tumors with low mutational burden produce fewer neoantigens and respond less reliably to neoantigen-targeted approaches. Immunosuppressive tumor microenvironments — particularly in pancreatic cancer and glioblastoma — can neutralize vaccine-stimulated T-cells before they reach their targets. CRISPR-enhanced platforms and AI-guided neoantigen selection algorithms are being developed to address these barriers. Market projections from industry analysts estimate the mRNA cancer vaccine market reaching $5–7 billion by 2030, with the first regulatory approvals anticipated between 2027 and 2029.
The Gathering Crisis: Vaccines Under Political Attack
Against the backdrop of this scientific progress, 2025 saw the most serious institutional disruption to the U.S. vaccine infrastructure since the modern immunization system was established. The proximate cause was the appointment of Robert F. Kennedy Jr. — a longtime vaccine critic and opponent of numerous vaccine mandates — as Secretary of Health and Human Services in February 2025.
Kennedy's actions moved rapidly. In June 2025, he dismissed all 17 sitting members of the Advisory Committee on Immunization Practices and replaced them with a set of appointees that independent experts described as lacking the scientific qualifications historically required for the panel. At least half of the new members had publicly questioned vaccination in some form. The committee's first formal meeting in September 2025 became, according to multiple medical press accounts, chaotic, relying heavily on anecdote over data. It voted to weaken COVID-19 vaccine recommendations, declined to recommend a combined MMRV vaccine for children under four, and postponed a vote on the hepatitis B birth-dose recommendation that had been standard practice since the 1990s. In December 2025, the reconstituted ACIP voted to eliminate the recommendation that all newborns receive hepatitis B vaccine at birth — a measure that had reduced hepatitis B infections in American children by 99%.
In January 2026, HHS overhauled the childhood vaccine schedule, reducing it from 18 recommended vaccines to 11, bypassing the standard evidence-based ACIP review process. Stanford University infectious disease professor Yvonne Maldonado — who was herself dismissed from ACIP — described the process as characterized by an "incredible lack of transparency," noting that no data, papers, or citations were provided to support the changes. The CDC's own scientific assessment accompanying the new schedule acknowledged that "loss of trust during the pandemic contributed to less adherence to the full CDC childhood immunization schedule," but the document cited no specific evidence justifying the removals.
The downstream consequences were already visible. By the time the new schedule was announced, 2025 had become the worst year for measles in the United States in more than three decades. More than 2,200 cases were confirmed across 45 states. South Carolina reported a single-county outbreak exceeding 960 cases. Three people died — two unvaccinated school-aged children and one adult. More than 70% of cases were in children, 93% were unvaccinated, and 11% required hospitalization.
A landmark modeling study published in JAMA on April 24, 2025 — authored by researchers at Stanford University, Baylor College of Medicine, and Texas A&M University — provided quantitative context for the stakes. Using a large-scale individual-based simulation model incorporating demographic, immunity, and disease-importation data from all 50 states, the team projected measles, rubella, polio, and diphtheria outcomes under varying vaccination scenarios over 25 years. At current vaccination rates, the model estimated an 83% probability that measles would become endemic in the United States again within approximately 21 years, producing roughly 851,300 cases. A 5% increase in vaccination coverage would prevent endemicity, reducing cases to 5,800. A 10% decrease would produce 11.1 million cases. Under a 50% vaccination decline, the model projected 51.2 million measles cases, 9.9 million rubella cases, 4.3 million polio cases, 10.3 million hospitalizations, and 159,200 deaths over 25 years. Rubella would become endemic in approximately 18 years under such conditions; polio in approximately 20 years. The study authors noted that "even under current vaccination levels," measles may become endemic "without improved vaccine coverage and public health response."
Former CDC Director Susan Monarez — who described herself as ousted by Kennedy over pressure to pre-approve recommendations without scientific evidence — testified before a Senate committee that more children would die of vaccine-preventable illnesses under the current leadership's policies. She specifically named measles, polio, diphtheria, and whooping cough as diseases whose resurgence was increasingly probable.
Insurance coverage for the altered schedule also became uncertain. The Affordable Care Act requires full coverage of ACIP-recommended vaccines for routine use; vaccines removed from routine-use designation lose that protection. The industry trade group AHIP pledged to continue covering vaccines on the schedule as of September 1, 2025, through the end of 2026 — a temporary measure leaving families facing the prospect of paying $180–$250 per MMR vaccine series out of pocket after that pledge expires. The National Health Law Program warned that low-income children served by the Vaccines for Children program face particular risk, since VFC coverage is tied directly to ACIP recommendations.
Plaintiffs have sought legal redress. A coalition of health advocates sued Kennedy and HHS over schedule changes, accusing the Secretary of working to "dismantle the longstanding, Congressionally-authorized, science- and evidence-based vaccine infrastructure," and asking courts to vacate the removal of healthy children and pregnant women from the COVID-19 vaccine schedule.
Key Researchers and Their Contributions
Stanley Plotkin, MD (b. 1932): Developer of the rubella vaccine (1969) and co-developer of the RotaTeq rotavirus vaccine; editor of Plotkin's Vaccines; Senior Life Member, IEEE. His rubella work directly eliminated congenital rubella syndrome from the United States.
Maurice Hilleman, PhD (1919–2005): Merck Research Laboratories. Developed or substantially improved over 40 vaccines including measles, mumps, rubella, hepatitis A, hepatitis B, chickenpox, meningitis, and pneumococcal disease. Widely regarded as the most productive vaccinologist in history.
Jonas Salk, MD (1914–1995): Developed the inactivated poliovirus vaccine (IPV), introduced 1955. The mass trial involved 1.8 million children and was among the largest clinical trials in history; IPV reduced U.S. polio incidence by more than 96% within a decade.
Katalin Karikó, PhD and Drew Weissman, MD, PhD: University of Pennsylvania. Nobel Prize in Physiology or Medicine, 2023. Their discovery that pseudouridine nucleoside modification of mRNA could dramatically reduce immunogenicity and improve translation efficiency made stable, clinically usable mRNA vaccines possible, enabling both COVID-19 vaccines and the current cancer vaccine pipeline.
Ugur Sahin, MD, PhD: Co-founder of BioNTech. Leading developer of personalized mRNA cancer vaccines and co-developer of the Pfizer-BioNTech COVID-19 vaccine. BioNTech's BNT111 (melanoma) and BNT122 (neoantigen vaccine) programs are among the most advanced therapeutic cancer vaccine candidates in clinical development.
Elias Sayour, MD, PhD: University of Florida. Pioneered lipid nanoparticle-mRNA cancer vaccine delivery systems; led the first human trial of a personalized mRNA glioblastoma vaccine and developed a "universal" mRNA immune activator showing cross-tumor anti-cancer effects in preclinical models, published in Nature Biomedical Engineering (2025).
Peter J. Hotez, MD, PhD: Texas Children's Hospital/Baylor College of Medicine. Co-developer of a low-cost recombinant protein COVID-19 vaccine and a prominent researcher in neglected tropical disease vaccines; co-author of the landmark 2025 JAMA vaccine modeling study.
Vinod Balachandran, MD: Memorial Sloan Kettering Cancer Center. Conducted the landmark pancreatic cancer neoantigen vaccine trials showing durable immune responses and significantly longer recurrence-free survival among patients with vaccine-induced T-cell responses.
Kennedy's Criticisms: A Spectrum from Discredited to Legitimately Debated
Any balanced assessment of the current crisis must grapple honestly with a central tension: some of Robert F. Kennedy Jr.'s concerns echo genuine scientific debates, while others rest on evidence the scientific community has repeatedly and conclusively rejected. Understanding the difference matters enormously, because conflating the two — either dismissing all criticism as conspiracy theory or accepting all of it as vindication — produces the worst possible policy outcomes.
The Thimerosal Controversy
Kennedy's most longstanding campaign has been against thimerosal, an ethylmercury-based preservative used in some multi-dose vaccine vials. His 2005 article "Deadly Immunity," published in both Rolling Stone and Salon.com, alleged a government conspiracy to conceal thimerosal's link to autism. Salon issued five corrections and its editor later described the piece as "the worst mistake of my career." Kennedy's 2014 book Thimerosal: Let the Science Speak extended the argument, conflating the well-established neurotoxicity of methylmercury — the organic mercury found in fish — with ethylmercury, a chemically distinct compound that is metabolized and eliminated from the body far more rapidly. Multiple large prospective studies across different populations have found no link between thimerosal-containing vaccines and autism or neurodevelopmental disorders. Thimerosal was voluntarily phased out of all routine childhood vaccines in the United States beginning in 2001 — not because evidence of harm emerged, but as a precautionary measure to address public concern — and autism diagnosis rates continued to rise afterward, undermining the central causal claim. The WHO's Global Advisory Committee on Vaccine Safety conducted a comprehensive review and found no evidence of harm from thimerosal at vaccine doses. Under Kennedy's HHS leadership, thimerosal was removed from the remaining ~5% of flu vaccines that still used it, and Kennedy urged other nations to follow suit — a move that infectious disease specialists warned could erode confidence in vaccine programs globally, particularly in low-income countries where multi-dose vials preserved with thimerosal are essential to cost-effective immunization campaigns.
Aluminum Adjuvants
Kennedy's more recent focus has been on aluminum salts — compounds like aluminum hydroxide and aluminum phosphate that have been used as vaccine adjuvants since the 1920s. Adjuvants amplify immune response, allowing smaller antigen doses to confer protection; without them, many vaccines would be far less effective or require multiple additional doses. Kennedy has claimed aluminum adjuvants are neurotoxic and linked to autism, asthma, autoimmune disease, and food allergies. He ordered the CDC to update its autism webpage from language stating that vaccines do not cause autism to language asserting this claim is "not evidence-based" — a change that specialists called scientifically unwarranted. When a large Danish study of 1.2 million children born over more than two decades, published in the Annals of Internal Medicine in 2025, found no significant association between aluminum-containing vaccine exposure and any of dozens of childhood health conditions, Kennedy demanded retraction, calling the study a "deceitful propaganda stunt." The journal's editor-in-chief defended the study as "among the strongest research currently available" on the subject and declined. Biostatisticians and vaccinologists reviewing Kennedy's critique described it as a textbook case of cherry-picking: he dismissed the main analysis entirely and instead elevated two figures from 15 supplementary tables, which the study's own authors had explicitly disclaimed as unsuitable for causal inference. A 2011 German study found no increased allergy risk in vaccinated children; a 2023 U.S. database analysis that briefly suggested an asthma association was found to disappear entirely once confounded by breastfeeding status — and could not be replicated. The FDA has concluded that the quantities of aluminum in vaccines represent an "extremely low risk to infants," noting that ambient dietary aluminum — from food, water, soil, and breast milk — substantially exceeds vaccine exposure.
Where Kennedy Has Had Points Worth Discussing: COVID-19 Vaccines
The COVID-19 vaccine experience introduced genuine scientific controversies that the public health community did not always handle with full transparency — and this matters enormously because the credibility of vaccine advocacy depends on acknowledging real findings, not suppressing uncomfortable ones.
The clearest example is myocarditis. The Phase 3 clinical trials for both Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273), while documenting a satisfactory safety profile in their enrolled populations, did not detect myocarditis — an inflammation of the heart muscle — as a vaccine-associated adverse event. This was not necessarily evidence of concealment; the trials enrolled tens of thousands of participants, but myocarditis after mRNA vaccination was subsequently found to occur at rates of approximately 1–5 cases per 100,000 doses in the highest-risk group (males aged 12–24, after the second dose), a rate that would require a much larger trial, or a trial specifically designed and powered to detect rare cardiac events, to identify. As a 2022 peer-reviewed report in Karger noted, "preapproval studies often involve a relatively large sample which may be sufficient for ensuring safety and effectiveness, but insufficient for detecting rare or very rare adverse events." The signal emerged clearly in post-authorization surveillance, particularly through Israel's national health data (which identified a causal association in June 2021, within months of mass vaccination) and through the CDC Vaccine Safety Datalink.
The FDA responded by adding a myocarditis warning to the mRNA vaccine prescribing information in 2021 and updated this warning in 2023 and again in 2024 to include quantified incidence data and cardiac MRI findings. A 2024 National Academies of Sciences, Engineering, and Medicine evidence review confirmed a causal link between mRNA COVID-19 vaccines and myocarditis, especially in young males after the second dose. Most cases resolved without treatment and clinical outcomes have generally been reassuring, though FDA has required manufacturers to conduct ongoing long-term cardiac follow-up studies, the results of which are still pending. A systematic review published in 2023 found that as many as 70% of studies reporting vaccine-associated adverse events during the early rollout did not stratify by sex and age with sufficient granularity to capture the elevated risk in young males — a methodological failure that, while not intentional suppression, contributed to a perception that the signal was being minimized. The risk of myocarditis from COVID-19 infection itself is, by systematic meta-analysis, approximately 42 times higher than from vaccination; this context was not always prominently communicated during early public messaging.
A second legitimate concern involves the design and unblinding of COVID-19 vaccine trials. Following Emergency Use Authorization, both Pfizer and Moderna offered placebo recipients the option to receive the active vaccine — a decision with genuine ethical justification (participants should not be denied a demonstrated benefit) but one that had real scientific costs. As Stanford epidemiologist Steven Goodman noted at the time, early unblinding was "a casualty of working at warp speed," limiting the ability to collect robust long-term safety and efficacy data from a randomized placebo-controlled cohort. Published scientific debate in Science and The Lancet acknowledged this tradeoff explicitly, and it was recognized within mainstream medicine, not just by critics. Additionally, the feasibility of maintaining blinding was compromised by the strong and easily recognizable systemic side effects of the mRNA vaccines compared to saline placebo, raising questions about inadvertent unblinding that researchers openly debated in the peer-reviewed literature.
A third area involves the adequacy of adverse event surveillance. Kennedy has characterized VAERS (the Vaccine Adverse Event Reporting System) and related infrastructure as inadequate, and HHS has claimed these systems "have become templates of regulatory malpractice." Mainstream vaccine scientists — including Paul Offit, who pointed to the rapid detection of myocarditis and rare clotting events as evidence the systems work — strongly contested this characterization. There is, however, a documented and well-established limitation of VAERS as a passive surveillance system: it is subject to significant underreporting of genuine adverse events and to overcounting through stimulated reporting during periods of heightened media attention. The scientific community has advocated for robust active surveillance through systems like the Vaccine Safety Datalink for decades precisely because passive reporting has known blind spots. Kennedy's critique of passive surveillance has legitimate foundations; his conclusion — that these limitations warrant dismantling the vaccine schedule — does not follow from that premise.
Tossing Out the Baby With the Bathwater
The tragedy of the current moment, as many scientists and public health experts have articulated, is that legitimate post-COVID scrutiny of regulatory processes and pharmaceutical transparency — scrutiny that the scientific community itself had already been conducting — has been hijacked and weaponized to discredit an entire century of vaccinology. There is a meaningful difference between calling for more rigorous and transparent adverse event surveillance for novel vaccine platforms and concluding that the hepatitis B birth dose — one of the most exhaustively studied and safety-validated interventions in pediatric medicine, responsible for eliminating 99% of childhood hepatitis B infections in the United States — should be eliminated from the schedule with no supporting evidence. There is a difference between advocating for better long-term myocarditis follow-up in young males and telling parents that the measles vaccine "causes deaths every year," a claim the Infectious Diseases Society of America has specifically rebutted as false for healthy recipients.
Kennedy has oscillated in his stated positions over time — writing in 2015 that he is "pro-vaccine" and had vaccinated all six of his own children, then stating in 2023 that "there is no vaccine that is safe and effective." This trajectory reflects not a disciplined scientific critique but a maximalist rhetorical posture that renders serious, technically grounded reform impossible. The result is that every genuine question — about adjuvant science, about clinical trial design, about the limits of passive surveillance, about the appropriate risk-benefit calculus for healthy young males receiving COVID boosters — becomes contaminated by association with claims that are demonstrably false and potentially lethal in their policy consequences. Scientists and public health officials who might otherwise welcome a rigorous safety dialogue find themselves in the position of defending the entire edifice of vaccinology against an undifferentiated attack, which serves neither science nor the public.
The international scientific community has not been passive about these issues. In 2025, the FDA itself — under new leadership — required placebo-controlled trials for all new COVID-19 vaccine formulations, a departure from the prior practice of treating annual COVID booster updates like influenza vaccine strain changes. This is a legitimate, though contested, regulatory judgment — and precisely the kind of calibrated, evidence-anchored policy debate that vaccine science needs and can withstand. What it cannot withstand, as the 2025 measles mortality data make plain, is the conflation of that debate with the abandonment of childhood immunization schedules built on decades of evidence and millions of protected lives.
The Road Ahead: Opportunity and Peril
Vaccinology in 2026 presents a study in contrasts. On one axis, the technology available to researchers has never been more powerful. AI-guided neoantigen prediction, self-amplifying RNA platforms, next-generation lipid nanoparticles with tissue-specific targeting, and CRISPR-enhanced vaccine design are converging to make personalized cancer vaccines a realistic clinical tool. First approvals for therapeutic cancer vaccines in melanoma and potentially lung cancer are projected within two to three years. Research into vaccines against other non-communicable diseases — including vaccines targeting beta-amyloid in Alzheimer's disease, and vaccines to address opioid dependence — has entered clinical investigation.
On the other axis, the institutional and social infrastructure upon which vaccination depends — provider networks, insurance coverage, school requirements, public trust, and evidence-based policy governance — is under stress in the United States to a degree unseen since the pre-vaccine era. The JAMA modeling data make the arithmetic of herd immunity stark: measles requires above 90% population immunity to prevent endemic transmission, and the country's current vaccination rates are, in the words of Penn State epidemiologist Matthew Ferrari, sitting on "a knife's edge."
The international dimension amplifies the risk. U.S. funding cuts to USAID global vaccination programs and Gavi, the Vaccine Alliance, have reduced the resources available to eliminate disease reservoirs abroad — reservoirs from which unvaccinated American travelers can import pathogens with increasing frequency. Every international outbreak of measles, poliovirus, or diphtheria is, in effect, a potential importation event waiting to collide with the growing pockets of unimmunized children now distributed across nearly every American state.
Stanley Plotkin, who has watched the arc of this history from inside the laboratories where the vaccines were made, put the stakes plainly: "The only thing that might change things would be outbreaks of diseases that could have been preventable. But it will take a while, and so I am not optimistic that things will change in any favorable direction in the foreseeable future." The science of vaccines has never been more promising. Whether the social and political will to deploy that science at the scale required to protect human health will survive the current moment is a question that no laboratory can answer.
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