Understanding the COVID-19 Vaccine in Pregnancy and Breastfeeding
Dec 22, 2021
With the ever-evolving state of the COVID-19 pandemic, we have put together this current and timely episode for you to help navigate the often overwhelming world of the COVID-19 vaccine, Omicron variant, boosters, and how those might affect you in pregnancy or while breastfeeding. Our guest, Dr. Elisabeth Marnik has a PhD. in genetics and immunology, is a scientist, professor, and a passionate science communicator. Please join her and Dr. Sarah as they break-down how the immune system works and changes during pregnancy, and how the vaccine and booster work in conjunction to give you and your baby the protection you need.
The Immune System During Pregnancy
The main job of the immune system is to identify when there is something foreign present, such as a virus, attack it, and get rid of it because it thinks that it's something that's going to make you sick. In most cases - this is a good thing! But that also means that your immune system is primed to identify your fetus and placenta as being foreign. It therefore becomes suppressed during pregnancy so as not to “attack” your baby and developing placenta: your immune system naturally lowers its defenses in pregnancy. This phenomenon ensures a healthy pregnancy, but it also leaves you more at risk of getting sick or having more severe complications from illness than the general population, as a consequence. Vaccines are encouraged for pregnant people because they are at higher risk of contracting illness and less primed to fight it if they do.
How does the Vaccine Affect the Immune System?
The main difference between immunity brought to you by a vaccine rather than being infected with a virus first hand is that vaccines infect you with a small part of the virus as opposed to the whole. In both cases - your immune system goes through the exact same steps! For example, if somebody is infected with SARS-CoV-2, they are exposed to all 29 proteins that make up the virus. Their body is more likely to react adversely and begin spreading the virus throughout the body that can cause significant issues. For pregnant people, it can pass through the placenta and cause infection in the developing fetus, which can be very dangerous. When the vaccine introduces your body to a very small part of the virus, called the spike protein, without the rest of its components, it can’t replicate and bind to your cells in the same way (causing full illness). Once your immune system sees the spike protein however, it can begin mounting an immune response just like it would with exposure to the full virus. Think of it like training for a marathon or playing an instrument - you might be able to perform without practicing first, but it sure helps!
What about Natural Immunity?
Like mentioned above, your immune system goes through the exact same steps it would if it’s building antibodies naturally or from a vaccine - the vaccine is not giving your immune system some new job to do that is more dangerous. It’s important to keep in mind that both immune responses are natural. A helpful way to consider it is not as “natural immunity” but rather as “infection acquired” immunity vs. “vaccine acquired immunity”.
Let’s talk more about Vaccines in Pregnancy:
Timing, Placenta & Breastmilk
We now have new, clear data on the COVID-19 vaccines that specifically look at this: there's no increased risk, or risk of miscarriage, from getting vaccinated in the first trimester of pregnancy. Moreover, data shows that the vaccine components themselves only stick around in your body for a very short period of time - just long enough to get your immune system to respond. The vaccine doesn’t have time to pass through the placenta, but what can pass through are the antibodies your body makes in the aftermath, giving your baby some passive immunity. Likewise, new data shows that the vaccine cannot be passed to the baby through breastmilk, but certain types of antibodies can - even some that cannot be passed through the placenta during pregnancy! Both in pregnancy and through breastfeeding, your baby will not be exposed to the vaccine, but will be able to get some protection and passive immunity through antibodies that can pass through the placenta and breast milk if the pregnant/breastfeeding person receives the vaccine.
Why do we need Boosters?
Boosters may seem like yet another new, laborious step imposed on us, or they may seem to pose a challenge to the efficacy of the initially recommended doses, but their advent is much less sinister and complicated - it just has to do with the timing of clinical trials! Because of the recently unprecedented challenges faced in battling a global pandemic - the high death toll, quick spread, and deeply troubling disruptions to our regular lives and mental health - trial periods for the COVID vaccines were put on shorter clinical intervals. Researchers couldn't do six month or yearly intervals between dose one and dose two because of the need to maximize the data proving it was effective and that it was safe. Now with longer trials and more research, it has been found that a booster shot is needed to increase the efficacy of the vaccine - and it is proving to be true with the spread of the Omicron variant. It’s not unusual to need a booster, several existing vaccines require it (like the MMR vaccine). The booster shot deposits another reminder (spike protein) for your immune system to remember and solidify what it is looking for and fighting against when it comes to COVID-19!
Dr. Marnik is five weeks pregnant and received her booster shot. Now more than ever, as soon as you're eligible, you should be getting one too no matter where you are in pregnancy.
Listen to the full episode for more details and great analogies from Dr. Marnik and Dr. Sarah, and please check-out the links below for references to today’s episode and information.
Stay safe and stay well.
Dr. Elisabeth Marnik
IG: @sciencewhizliz
Taking you from anxious and overwhelmed to confident during your childbirth experience: Pregnancy to Parenthood Online Prenatal Masterclass
References
Risk of COVID in pregnancy
- https://www.cmaj.ca/content/193/16/E540.long
- https://www.cdc.gov/mmwr/volumes/70/wr/mm7047e2.htm
- https://www.cdc.gov/mmwr/volumes/70/wr/mm7047e1.htm
Pregnancy and Vaccination
- https://www.nejm.org/doi/full/10.1056/NEJMc2114466
- https://www.science.org/doi/10.1126/scitranslmed.abi8631
- https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2783112
- https://www.nejm.org/doi/full/10.1056/NEJMx210016?query=recirc_curatedRelated_article
- https://www.nejm.org/doi/full/10.1056/NEJMc2113891
- https://www.jci.org/articles/view/150319
- https://jamanetwork.com/journals/jama/fullarticle/2784193
- https://www.researchsquare.com/article/rs-798175/v1
Breastfeeding
- https://jamanetwork.com/journals/jama/fullarticle/2778766
- https://publications.aap.org/pediatrics/article/148/5/e2021052286/181337/SARS-CoV-2-Antibodies-in-Breast-Milk-After
- https://www.jci.org/articles/view/150319
- https://www.medrxiv.org/content/10.1101/2021.03.05.21252998v1
- https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2782982
- https://www.nature.com/articles/d41586-021-01680-x
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