Did a study really show a ten‑fold increase in deaths among girls immunized with diphtheria-tetanus-pertussis (DTP) vaccine?

How RFK continues to fuel the global anti-vaccine movement.

In a recorded video statement from Robert F. Kennedy Jr. (RFK Jr), prepared for a fundraiser hosted by the Gates Foundation and the European Union for Gavi, the Vaccine Alliance, the Secretary of Health and Human Services emphasized the importance of science and evidence in informing decision-making. RFK praised Gavi for its work on making vaccines more affordable. But he criticized the organization for “ignoring the science”.

In his just over three-minute address, he presented some so-called facts from an observational study conducted in urban Guinea-Bissau in the early 1980s and published in 2017. An observational study is a type of research where scientists observe and analyze outcomes without assigning interventions to participants, simply watching how things naturally occur.

This study reported a nearly ten-fold increase in mortality among girls vaccinated with diphtheria-tetanus-pertussis (DTP) without simultaneous oral polio vaccine (OPV) compared to girls who had not yet received DTP. The findings were based on a very small sample of five deaths—four in the vaccinated group and one in the unvaccinated group. The authors acknowledged the findings as preliminary due to the small sample size and methodological limitations. In a follow-up observational study of nearly 2,400 infants in the same setting and conducted by many of the same authors, researchers observed no statistically significant increase in female mortality associated with early DTP vaccination after adjusting for nutritional status and other important factors. The study concluded that early DTP was not associated with increased mortality, including among females.

The concept that was explored in these studies is the “non-specific effects” of vaccination. The idea refers to the observation that some vaccines affect the immune responses to human pathogens other than those targeted by the vaccine. Epidemiological and immunological studies have shown that live attenuated vaccines (e.g., BCG and measles vaccines) can enhance protection against unrelated infections. This likely occurs through an enhanced immune response to a broad range of infections. In contrast, certain non-live vaccines (e.g., DTP) have occasionally been associated with increased susceptibility to non-targeted infections, like the study referenced by RFK Jr.

Experts in Nature note that data on the negative non-specific effects of non-live vaccines from multiple studies are mixed and inconsistent, with several studies indicating potential sex-differential negative non-specific effects and others showing no statistically significant association. This heterogeneity underscores the complexity and uncertainty surrounding these findings.

One of the many problems with RFK Jr.’s analysis, among others, is that the studies showing potentially harmful, non-specific effects, such as the one he referenced, are all observational and at high risk of bias. While such information may indeed be a cause for additional inquiry, it certainly does not merit a radical policy change, particularly for a vaccine that has saved tens of millions of lives.

Seemingly conflating two separate points about DTP, RFK Jr. also claims that Gavi supports the use of the whole-cell pertussis vaccine instead of the safer acellular vaccine. While it is true that whole-cell pertussis vaccines typically have higher reactogenicity - meaning it causes mostly minor side effects such as injection-site pain and temporary fever - the immunity from whole-cell vaccines lasts longer, whereas protection from the acellular vaccine wanes more quickly, requiring additional boosters. Therefore, especially in settings where pertussis remains a serious threat, the whole-cell vaccine remains an important choice despite its reactogenicity.

In a world where one of the leading threats to human health is a lack of trust in science overall and vaccine hesitancy, RFK Jr. is continuing to deliver a life-threatening message. This is a part of a dedicated campaign to discredit vaccines. His measles vaccine tirade has been debunked and discredited, and so he has chosen a new target: DTP, where science requires some explanation. By picking and choosing his evidence, he has turbocharged the global anti-vaccination movement as well as planted a seed of distrust around Gavi, an organization that is rightly credited with averting nearly 20 million deaths in its 25-year history.

One surprise about his video message was that he focused on DPT instead of the human papillomavirus vaccine, which prevents over 90 percent of cervical cancers. Why is that a surprise? Because RFK Jr. is currently suing the vaccine manufacturer and receives a payout for every plaintiff he brings to the case. Gavi is the largest procurer of that vaccine.

The Trump administration's decision to pull out of one of the most successful global health efforts is not surprising. Despite saying otherwise, he has made clear that he is not in favor of vaccines or multilateral commitments. While Trump’s original rationale for cutting its contribution to Gavi was that it held a cash reserve, RFK Jr.’s story is different. Until Gavi follows his ‘science’, it can say goodbye to US support. And in an ironic twist to this announcement, today, they actually tried to use Gavi’s own platform to discredit vaccines.

The real story from the Gavi fundraising event today is that if other countries don’t step up with pledges and call out RFK’s mis- and disinformation, they are allowing the US to destroy hard-earned progress of decades, condoning US efforts to save pennies on the dollar and watch the world watch children die.

The authors would like to thank @Elliot HannElliot Hannon for his review of this piece.