Implications of Non-Specific Effects for Testing, Approving, and Regulating Vaccines

Christine Stabell Benn, Nelly Amenyogbe, Anders Björkman, Jorge Domínguez-Andrés, Eleanor N Fish, Katie L Flanagan, Sabra L Klein, Tobias R Kollmann, Kirsten Ohm Kyvik, Mihai G Netea, Naja Hulvej Rod, Frederik Schaltz-Buchholzer, Frank Shann, Liisa Selin, Sanne M Thysen, Peter Aaby


The current framework for testing and regulating vaccines was established before the realization that vaccines, in addition to their effect against the vaccine-specific disease, may also have "non-specific effects" affecting the risk of unrelated diseases. Accumulating evidence from epidemiological studies shows that vaccines in some situations can affect all-cause mortality and morbidity in ways that are not explained by the prevention of the vaccine-targeted disease. Live attenuated vaccines have sometimes been associated with decreases in mortality and morbidity that are greater than anticipated. In contrast, some non-live vaccines have in certain contexts been associated with increases in all-cause mortality and morbidity. The non-specific effects are often greater for female than male individuals. Immunological studies have provided several mechanisms that explain how vaccines might modulate the immune response to unrelated pathogens, such as through trained innate immunity, emergency granulopoiesis, and heterologous T-cell immunity. These insights suggest that the framework for the testing, approving, and regulating vaccines needs to be updated to accommodate non-specific effects. Currently, non-specific effects are not routinely captured in phase I-III clinical trials or in the post-licensure safety surveillance. For instance, an infection with Streptococcus pneumoniae occurring months after a diphtheria-tetanus-pertussis vaccination would not be considered an effect of the vaccination, although evidence indicates it might well be for female individuals. Here, as a starting point for discussion, we propose a new framework that considers the non-specific effects of vaccines in both phase III trials and post-licensure.

Original languageEnglish
JournalDrug Safety
Issue number5
Pages (from-to)439-448
Number of pages10
Publication statusPublished - May 2023


  • Diphtheria-Tetanus-Pertussis Vaccine
  • Female
  • Humans
  • Male
  • Vaccination/adverse effects
  • Vaccines, Attenuated


Dive into the research topics of 'Implications of Non-Specific Effects for Testing, Approving, and Regulating Vaccines'. Together they form a unique fingerprint.

Cite this