The term “sex” refers to the biological sex of female or male, whereas the term “gender” refers to sociocultural determinants (e.g., where a person may self-identify as woman, man, non-binary, among others).
Understanding the role of sex differences in health care is of great importance, especially in the context of vaccination. Indeed, males and females may have different antibody responses and adverse events after vaccination [1]. There are multiple mechanisms that account for sex differences: hormones, genes encoded in the X-chromosome, and changes in the microbiota (microorganisms living in our body) [2].
After some vaccines, females tend to have increased antibody responses, which could provide added protection. For example, females may have higher antibody levels after the trivalent influenza vaccine [3]. However, an increased reactivity of the immune system could potentially be related to problems as well – having a higher risk for autoimmune diseases [1]. Therefore, having an increased immune response can be beneficial, but its excess could also be harmful.
Moreover, a review suggested that females usually develop more adverse events after some vaccines [1]. Nevertheless, sex differences are still unclear. For instance, after the yellow fever vaccination, the majority of the adverse events were reported by females [4]. However, in another study, although most adverse events were reported by females, serious (more severe) events were more frequently reported by males [5].
It should be noted that these statistics may be affected by which sex tends to report side effects. For example, even if both sexes experience adverse events, perhaps one sex may choose to disregard minor side effects and report them less often than the other. That is one of the reasons why it is also important to consider the role of gender and sociocultural factors in research. Thus, future studies should differentiate whether the side effects are actually more frequent in one sex or if the reporting rates are affecting the result.
Stay tuned for future posts where we will also look at sex and gender differences in diseases and the immune system!
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Written by: Nicole
Edited by: María and Natasha
BioDecoded is a volunteer group committed to sharing accurate scientific information. For more information about vaccines or other scientific processes, please see previous posts or consult with your personal physician. If you have any questions about this topic, please comment or send them to our email.
References:
Fischinger, S., et al. (2019). Sex differences in vaccine-induced humoral immunity. Seminars in immunopathology, 41(2), 239–249. Available at: https://doi.org/10.1007/s00281-018-0726-5
Klein SL, et al. (2015) Sex-based differences in immune function and responses to vaccination. Transactions of the Royal Society of Tropical Medicine and Hygiene, 109(1):9-15. Available at: https://academic.oup.com/trstmh/article/109/1/9/1921905
Engler RJ, et al. (2008) Half- vs full-dose trivalent inactivated influenza vaccine (2004–2005): age, dose, and sex effects on immune responses. Arch Intern Med, 168:2405–14. Available at: https://pubmed.ncbi.nlm.nih.gov/19064822/
Harris, T., et al. (2017). Assessment of sex-specific differences in adverse events following immunization reporting in Ontario, 2012-15. Vaccine, 35(19), 2600–2604. Available at: https://doi.org/10.1016/j.vaccine.2017.03.035
Lindsey, N. P., et al. (2008). Adverse event reports following yellow fever vaccination. Vaccine, 26(48), 6077–82. Available at: https://doi.org/10.1016/j.vaccine.2008.09.009
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