Study shows higher mortality rates among vaccinated infants

A newly published analysis of health records from Louisiana has reported higher mortality rates among infants vaccinated during their second month of life compared with those who were unvaccinated during the same period, prompting renewed debate over vaccine safety research and data transparency.

The analysis, conducted by Children’s Health Defense (CHD) scientists Brian Hooker, Ph.D., and Karl Jablonowski, Ph.D., examined linked immunization and mortality records obtained from the Louisiana Department of Health.

The study was published Monday on Preprints.org, a platform for research papers that have not yet undergone peer review.

According to the authors, infants who received one or more vaccines between 60 and 90 days of life were between 29% and 74% more likely to die between 90 and 120 days of age than infants who were not vaccinated during that window.

The analysis further reported higher relative mortality rates among Black infants compared with white infants, and among female infants compared with male infants.

The researchers reviewed records of approximately 5,800 infant deaths in Louisiana between 2013 and 2024. Of these, 1,775 deaths could be matched precisely with immunization records, and a subset of 1,225 infants who survived beyond 90 days of life formed the core of the analysis.

At the two-month visit during the study period, infants typically received vaccines for hepatitis B, rotavirus, diphtheria, tetanus and pertussis (DTaP), Haemophilus influenzae type b (Hib), pneumococcal disease, poliovirus, and in some cases respiratory syncytial virus (RSV).

Hooker described the study as one of the first attempts to assess the cumulative effects of vaccines administered at the two-month visit in line with CDC recommendations.

He said the findings could be relevant as the Advisory Committee on Immunization Practices (ACIP) periodically reviews the childhood vaccination schedule.

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The analysis reported that the strongest individual association was observed with the rotavirus vaccine, which the authors said showed a 74% higher mortality rate among vaccinated infants compared with unvaccinated infants in the same age window.

When vaccines were analyzed in combination, mortality rates were reportedly higher among infants who received multiple shots at a single visit.

The researchers also reported that female infants showed the strongest associations, with some comparisons indicating mortality increases exceeding 80% and, in some cases, 100%. They suggested that sex-based differences in immune response could be a contributing factor, citing previous research indicating stronger immune reactions among females.

In addition, the study examined causes of death and reported differences in the distribution of causes between vaccinated and unvaccinated female infants, including a higher proportion of deaths attributed to infectious and nervous system conditions among vaccinated infants.

Hooker and Jablonowski emphasized that their findings show associations, not proof of causation, and described the work as a “proof-of-concept” demonstrating what they say is possible when immunization and death registries are linked.

They called on health authorities to make similar datasets available for independent analysis across other states and countries.

Public health authorities, including the CDC and the World Health Organization, have long maintained that childhood vaccines are safe and effective, citing extensive research showing that vaccination prevents millions of deaths worldwide each year.

They also note that observational studies can be affected by confounding factors and that findings from non-peer-reviewed research should be interpreted with caution.