Few people are likely surprised by the idea that the work of Peter Aaby will likely lead to millions of children dying from vaccine preventable diseases.

They probably think that his DTP studies have been scaring folks from getting vaccinated, and that has perhaps already led to some of the diphtheria outbreaks and deaths we have been seeing in many countries.
How Did Peter Aaby Lead to Millions of Children Dying from Vaccine Preventable Diseases?
Few could have imagined that Secretary RFK Jr would have called out Aaby’s work as the reason for his pulling $1.5 billion in funding to the organization.
Funding that would help vaccinate millions of children.

But that is where we are at.
In a recent recorded speech, Secretary RFK Jr said that Aaby’s study found that “girls vaccinated with DPT were 10 times more likely to die from all causes in the first six months of life than those children who were unvaccinated.”
Peter Aaby calls this the non-specific effects of vaccinations.
Although RFK Jr mentions a 2017 study, Peter Aaby’s first studies were done back in 2000, showing both positive and negative non-specific effects.
These effects were hardly ignored though, as RFK Jr implies.
Two task forces looked into the issue at the time, and they concluded that “the evidence does not support the deleterious effect of DTP.”
This is mostly because Aaby’s studies about non-specific effects are thought to be weak and at high risk of bias.
And get this, one of his latest studies didn’t even find the same deleterious effect of the DTP vaccine!
“We did not find that early-DTP was associated with increased female mortality as found in a previous study; differences in results may partly be due to a decline in overall mortality and changes in vaccination practices.”
Retesting the hypothesis that early Diphtheria-Tetanus-Pertussis vaccination increases female mortality: An observational study within a randomised trial
This study found that children who were “vaccinated had better anthropometric indices than no-DTP infants at birth and by 2 months of age.”
Will that change RFK Jr’s mind about taking away funding and immunizations from millions of kids?
Or can we expect the diphtheria, measles, and other outbreaks we are already seeing to get worse as even fewer children get vaccinated?
References
Sørensen MK, Schaltz-Buchholzer F, Jensen AM, Nielsen S, Monteiro I, Aaby P, Benn CS. Retesting the hypothesis that early Diphtheria-Tetanus-Pertussis vaccination increases female mortality: An observational study within a randomised trial. Vaccine. 2022 Mar 8;40(11):1606-1616. doi: 10.1016/j.vaccine.2021.06.008. Epub 2021 Jun 30. PMID: 34217570.
Kennedy pulls US support for Gavi's vaccine efforts https://www.cidrap.umn.edu/childhood-vaccines/kennedy-pulls-us-support-gavis-vaccine-efforts https://www.pbs.org/newshour/health/u-s-is-pulling-funding-from-gavi-global-group-that-has-paid-for-more-than-a-billion-kids-to-get-vaccinated
U.S. is pulling funding from Gavi, global group that has paid for more than a billion kids to get vaccinated
RFK Jr. singled out one study to cut funds for global vaccines. Is that study valid? https://www.npr.org/sections/goats-and-soda/2025/07/01/g-s1-74752/rfk-jr-vaccines-safety-gavi
Why diphtheria is making a comeback https://www.npr.org/sections/goatsandsoda/2024/01/23/1226155791/why-diphtheria-is-making-a-comeback
The WHO also looked specifically at this issue, and included 11 studies of DPT and mortality outcomes, concluding that it did not increase mortality.
Aaby’s study was small; it had 37 deaths in total, and as you say it was subject to bias.
None of this will influence Kennedy. He comes from the school of “I will stick to the science (but only the science that tells me what I want to hear, and to hell with all the rest)”