"What's the Deal With Vaccinating Expectant Mothers?"
Written by Vicky Diep
Edited by Christine Yee
July 31st 2021
Edited by Christine Yee
July 31st 2021
Since the beginning of time, the evolutionary and cultural history of our species has been shaped by our interactions with disease-causing bacteria and viruses. Such pathogens have shown themselves capable of toppling strong empires, forming tensions among groups of people, and needless to say, countless deaths as they attempt to invade and exploit our bodies time and time again. However, thanks to the rise of adaptive immunity in early vertebrate ancestors and its extensive evolutionary fine-tuning (Flajnik & Kasahara, 2020), we have been able to defeat such pathogens and stay one step ahead of the evolutionary arms race. Typically, adaptive immunity takes a few days to a few weeks to mount, because it takes time for our immune cells to multiply in number and undergo transformations that give them the ability to recognize foreign invaders. In the meantime, the pathogen is able to wreak havoc in the body, causing disease symptoms that could lead to death. Vaccines help close the lag time that it takes for our immune cells to begin recognizing a specific pathogen by exposing our body's immune system to an inactivated form or small part of that pathogen before infection takes place, so that our body is ready to fight the pathogen the moment it invades. Vaccines are the most cost-effective way of preventing disease and mortality in children under five (Orije et al., 2020). Besides vaccinating infants after birth, giving certain vaccines to mothers during pregnancy allows the newborn to also benefit from protection conferred by maternal antibodies during the first few months of life. But what are the benefits and risks associated with vaccines from the mother's perspective?
During pregnancy, the immune system of expecting mothers is suppressed to prevent it from reacting against her developing child, whose cells are different from her own. Although these changes are made to protect the fetus, they could also lower the mother's defenses against certain viral infections (Arora & Lakshmi, 2021). This could place immunocompromised women (such as those with diabetes mellitus, asplenia, chronic liver, lung, or heart disease, or autoimmune disorders such as HIV) at risk. Because of this, the US CDC “recommends one dose of a tetanus, diphtheria, and acellular pertussis vaccine” (Arora & Lakshmi, 2021), as well as the seasonal flu vaccine for all pregnant women. Women who live in or intend to travel to areas where they could be exposed to certain pathogens may be offered additional vaccines. In general, “all vaccines except live vaccines can be safely administered to pregnant women” (Arora & Lakshmi, 2021). Live vaccines are those that contain weakened forms of a pathogen capable of stimulating an immune response, but can no longer cause disease, unless it mutates within a host and regains that ability. Although reversion of a live vaccine to virulence is a rare event, it is contraindicated for immunocompromised people.
With all of the new vaccine roll outs amid the COVID pandemic, it’s important to note that vaccines consisting of DNA or RNA, such as the three coronavirus vaccines that have been approved by the FDA as of now, are not live vaccines because they do not contain any live coronavirus. Thus, they carry zero risk of reversion because they contain only genetic sequences that code for protein spikes on the coronavirus that stimulate the body's immune cells without causing disease, and are therefore safe for pregnant women and the immunocompromised.
Works Cited
Arora, M., & Lakshmi, R. (2021). Maternal vaccines—safety in pregnancy. Maternal Vaccines—safety in Pregnancy, Best Practice & Research Clinical Obstetrics & Gynaecology. doi:10.1016/j.bpobgyn.2021.02.002
Flajnik, M., Kasahara, M. Origin and evolution of the adaptive immune system: genetic events and selective pressures. Nat Rev Genet 11, 47–59 (2010). https://doi.org/10.1038/nrg2703
Orije, M. R., Maertens, K., Corbière, V., Wanlapakorn, N., Van Damme, P., Leuridan, E., & Mascart, F. (2020). The effect of maternal antibodies on the cellular immune response after infant vaccination: A review. Vaccine, 38(1), 20-28. doi:10.1016/j.vaccine.2019.10.025