Nicolas Hulscher, MPH

Across countries on three continents, a 1% increase in vaccine types before age one corresponded to a 0.47% increase in autism prevalence.

A new cross-national study from Italy’s National Research Council, spanning multiple developed countries across three continents, has identified a remarkably strong association between early-life vaccine intensity and autism prevalence. The number of vaccine types and doses administered before 12 months showed exceptionally high correlations with national autism rates.

A 1% increase in vaccine types before age one corresponded to a 0.47% increase in autism prevalence.

The correlation is enormous — r = 0.87 for vaccine types and r = 0.79 for vaccine doses. In regression models, vaccine intensity alone explained 81% of the variance in autism prevalence across nations.

This is not an isolated signal. It directly corroborates earlier U.S. state-level data from DeLong (2011) — and aligns with the 107 positive-association studies catalogued in the McCullough Foundation’s Landmark Autism Report.

Key Findings

Coccia used cross-national 2021 autism incidence data paired with WHO-reported infant vaccine schedules. Countries were grouped into relatively comparable healthcare and surveillance systems (North America, Europe, and advanced Asian nations) to reduce detection and reporting bias. The primary exposures were:

• number of vaccine types given ≤12 months, and
• total number of doses delivered ≤12 months.

Autism prevalence per 100,000 children served as the outcome, and general vaccination coverage rates were statistically controlled so only vaccine intensity and timing were isolated.

The results were striking but unfortunately expected:

• Countries such as the U.S., Canada, Australia, Japan, South Korea, and Singapore give ~15 vaccine types and 20 doses before age one — and have the highest autism prevalence (~1,273 per 100k).
• Countries like Norway, Finland, Denmark, Italy, and the UK give ~8 vaccine types and 9 doses — and have significantly lower autism rates (~834 per 100k).
• A 1% increase in vaccine types before age one corresponded to a 0.47% increase in autism prevalence.
• The regression model (log–log) explained 81% of the variance.

Coccia then used quadrant mapping to classify nations:

• Critical Risk Zone: high vaccine intensity + high autism (U.S., Canada, Australia, Japan, South Korea, Singapore)
• Protection Zone: low vaccine intensity + low autism (Nordic countries)
• Transitional Zone: countries on track to move upward as vaccine intensity rises (Italy, UK)

The conclusion is clear: Early-timed and compound vaccination strongly tracks with rising autism rates.

How DeLong (2011) Fits In

DeLong’s analysis of CDC data found that each 1% rise in U.S. childhood vaccination coverage was associated with ~680 additional cases of autism and speech/language impairment nationwide.

Where DeLong examined state-level associations between how many children were fully vaccinated and subsequent autism/SLI prevalence, Coccia provides the first true cross-national dose–response analysis — showing that the number of vaccine types and doses given before age one powerfully predicts national autism prevalence.

Both studies point in the same direction:
more vaccination in early life → higher autism prevalence.

How This Strengthens the McCullough Foundation’s Landmark Autism Report

Our Autism Report reviewed 136 vaccine-related studies:

• 107 studies inferred positive associations between vaccination or vaccine components and ASD/NDDs.
• All 12 vaccinated vs unvaccinated studies found better neurodevelopmental outcomes in completely unvaccinated children, including far lower rates of autism.
• Found strong, consistent increases in cumulative vaccine exposure during early childhood and the reported prevalence of autism across successive birth cohorts.

We concluded:

Combination and early-timed routine childhood vaccination constitutes the most significant modifiable risk factor for ASD, supported by convergent mechanistic, clinical, and epidemiologic findings, and characterized by intensified use, the clustering of multiple doses during critical neurodevelopmental windows, and the lack of research on the cumulative safety of the full pediatric schedule.

Coccia independently arrived at a highly similar conclusion:

This study offers a critical contribution to the ongoing discourse on vaccine safety and neurodevelopment by identifying a statistically significant association between early-life vaccine intensity and national autism rates.

All evidence points to the same conclusion:

Early, clustered vaccination is the strongest modifiable driver of rising autism rates.

Nicolas Hulscher, MPH

Epidemiologist and Foundation Administrator, McCullough Foundation

Support our mission: mcculloughfnd.org

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From the Daily Caller News Foundation

By Samuel Peterson

Unelected regulators and bureaucrats from the United Nations have pushed for crushing the global economy in the name of saving the planet.

In October, the International Maritime Organization (IMO), a specialized agency within the U.N., proposed a carbon tax in order to slash the emissions of shipping vessels. This comes after the IMO’s April 2025 decision to adopt net-zero standards for global shipping.

Had the IMO agreed to the regulation, it would have been the first global tax on greenhouse gas emissions. Thankfully, the United States was able to effectively shut down those proposals; however, while these regulations have been temporarily halted, the erroneous ideas behind them continue to grow in support.

Proponents of carbon taxes generally argue that since climate change is an existential threat to human existence, drastic measures must be taken in all aspects of our lives to address the projected costs. People should eat less meat and use public transportation more often. In the political arena, they should vote out so-called “climate deniers.” In the economic sphere, carbon taxes are offered as a technocratic quick fix to carbon emissions. Is any of this worth it? Or are the benefits greater than the costs? In the case of climate change, the answer is no.

Carbon taxes are not a matter of scientific fact. As with all models, the assumptions drive the analysis. In the case of carbon taxes, the time horizon selected plays a major role in the outcome. So, too, does the discount rate and the specific integrated assessment models.

In other words, “Two economists can give vastly different estimates of the social cost of carbon, even if they agree on the objective facts underlying the analysis.” If the assumptions are subjective, as they are in carbon taxes, then they are not scientific facts. As I’ve pointed out, “carbon pricing models are as much political constructs as they are economic tools.” One must also ask whether carbon taxes will remain unchanged or gradually increase over time to advance other political agendas. In this proposal, the answer is that it increases over time.

Additionally, since these models are driven by assumptions, one would be right in asking who gets to impose these taxes? Of course, those would be the unelected bureaucrats at the IMO. No American who would be subject to these taxes ever voted for the people attempting to create the “world’s first global carbon tax.” It brings to mind the phrase “no taxation without representation.”

In an ironic twist, imposing carbon taxes on global shipping might actually be one of the worst ways to slash emissions, given the enormous gains from trade. Simply put, trade makes the world grow rich. Not just wealthy nations like those in the West, but every nation, even the most poor, grows richer. In wealthy countries, trade can help address climate change by enabling adaptation and innovation. For poorer countries, material gains from trade can help prevent their populations from starving and also help them advance along the environmental Kuznets curve.

In other words, the advantages of trade can, over time, make a country go from being so poor that a high level of air pollution is necessary for its survival to being rich enough to afford reducing or eliminating pollution. Carbon taxes, if sufficiently high, can prevent or significantly delay these processes, thereby undermining their supposed purpose. Not to mention, as of today, maritime shipping accounts for only about 3% of total global emissions.

The same ingenuity that brought us modern shipping will continue to power the global economy and fund growth and innovation, if we let it. The world does not need a layer of global bureaucracy for the sake of virtue signaling. What it needs is an understanding of both economics and human progress.

History shows that prosperity, innovation, and free trade are what make societies cleaner, healthier, and richer. Our choice is not between saving the planet and saving the economy; it is between free societies and free markets or surrendering responsibility to unelected international regulators and busybodies. The former has lifted billions out of poverty, and the latter threatens to drag us all backwards.

Samuel Peterson is a Research Fellow at the Institute for Energy Research.