Historically vaccines have taken a decade or longer to develop and get to market. Due to the severity and spread of COVID-19, there was a massive demand to create vaccines as quickly as possible. We have three vaccines currently approved by the FDA under an emergency authorization use in just a year. Pregnancy can increase your risks for severe illness from COVID-19. Despite pregnancy increasing COVID-19 risks, clinical trials did not include pregnant participants. Although studies are beginning to focus on these vaccines and pregnancy, it will be months or even years before we have results. This episode dives into the available evidence on the safety and efficacy of COVID-19 vaccines during pregnancy so you can make an informed decision on whether to get the vaccine.
Additional COVID-19 Resources
- American College of Obstetricians and Gynecologists
- Royal College of Obstetricians and Gynaecologists
- World Health organization
- Centers for Disease Control & Prevention
- Click here for more Pregnancy Podcast episodes on COVID-19.
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Article and Resources
The Controversy of Vaccines
Vaccines are a very controversial and complex topic. Some professionals spend their lives dedicated to researching and studying vaccines and their safety. This article is an overview of the COVID-19 vaccine to give you a good base on the information available. I have spent a significant number of hours and days, and weeks on this topic, and I hope you find the information in this episode to be helpful as you are navigating the decision about whether or not to get the COVID-19 vaccine during your pregnancy.
Researching vaccines is incredibly challenging. It is easy to find yourself on a website that appears to be unbiased, only to discover an agenda, and it is firmly pro or con vaccine. My goal with this article is to help you sift through all of the data out there to educate yourself and make an informed decision that is right for you.
These are decisions that you should be making with your doctor or midwife. I cannot possibly cover every facet of this topic, and if you have further questions or concerns, I urge you to bring them up with your care provider. I am not for or against the COVID-19 vaccine. I firmly believe that you should be able to choose whether or not you receive any vaccine or medical intervention. If you are reading this article, you can make an informed decision and not one based on fear.
COVID-19 is a disease caused by the SARS-CoV-2 respiratory virus. This novel virus emerged towards the end of 2019 and has continued to spread globally. As of March 26, 2021, there have been over 125 million cases of COVID-19 worldwide and over 2.7 million deaths. The SARS-CoV-2 virus is transmitted primarily from air droplets. When someone infected coughs, breathes, or sneezes, the virus can travel in aerosols in the air, which could be breathed in or land on a surface.
Different Variants of COVID-19
SARS-CoV-2, like any virus, evolves and mutates over time. These mutations create different variants of the original virus. As COVID-19 has continued to spread, we have seen additional variants of the virus. The variants can affect how transmissible the virus is and the severity of symptoms. It is possible as more data becomes available that vaccines may need to be updated to include more protection against different variants. The World Health Organization states that COVID-19 vaccines currently in development or have been approved are expected to provide at least some protection against new virus variants.
The main symptoms of this virus are fever, cough, and shortness of breath. These could appear anywhere between 2-14 days after exposure to the virus. Emergency warning signs include difficulty breathing or shortness of breath, persistent pain or pressure in the chest, confusion or inability to arouse, and bluish lips or face. If you have any symptoms, you want to reach out to your doctor or midwife right away. You want to be proactive as much as possible and not wait. It is estimated that around 20% of cases are asymptomatic, which means you have no noticeable symptoms. Individuals who are positive for SARS-CoV-2 but asymptomatic can still spread the virus to others.
Defining Mild, Moderate, & Severe Symptoms
Symptoms of COVID-19 are classified as mild, moderate, and severe. Mild means that there is no shortness of breath or difficulty breathing. Moderate cases involve evidence of lower respiratory disease and abnormal chest imaging. Severe cases have decreased oxygen saturation. Critical illness includes individuals with respiratory failure, septic shock, and organ failure. The most severe cases can result in intensive care admission, mechanical ventilation, or death. Many underlying conditions can put you at a higher risk for severe COVID-19, including diabetes and cardiovascular disease. Even pregnancy can increase your risk for severe symptoms of COVID-19.
COVID-19 During Pregnancy
According to the CDC, although the overall risk of severe illness is low, pregnant people are at an increased risk for severe illness from COVID-19 compared to non-pregnant people. Additionally, pregnant people with COVID-19 might be at increased risk of adverse pregnancy outcomes, such as preterm birth, compared with pregnant women without COVID-19.
If you test positive for COVID-19, it may impact your birth. Some hospitals and birth centers are not allowing partners present for expecting mothers who are positive for COVID-19. If you have any questions about how a positive test could impact your prenatal care or birth, please talk to your doctor or midwife.
The COVID-19 Vaccine
Historically vaccines have taken a decade or longer to develop and get to market. Due to the severity and spread of COVID-19, there was a massive demand to get vaccines developed as quickly as possible. Pharmaceutical companies utilized government funding, previous research on SARS and MERS, and vaccine technology that is quick to produce to get vaccines to the public in under a year.
Vaccines are required to go through vigorous testing and oversight before approval for use. While there has been skepticism about these vaccines due to the quick approval process, they still underwent the typical development stages. Preclinical trials may involve animal testing as drug manufacturers dial in the vaccine and dosage. Once a trial vaccine is created, the manufacturer tests it during Phase I in small groups of healthy people. Phase II expands the testing group to more people with characteristics similar to those for whom the vaccine is intended. In Phase III, the vaccine is given to thousands of people and further tested for efficacy and safety.
The vaccines currently approved in the United States received emergency use authorization from FDA. The FDA can issue an emergency use authorization for a drug, vaccine, or treatment during a public health emergency if they deem the benefits outweigh the risks. This makes the approval process shorter and less involved than required for full FDA approval. After approval, the FDA continues to monitor vaccine safety, and the Vaccine Adverse Event Reporting System (VAERS) collects and analyzes reports of adverse from vaccines.
How COVID-19 Vaccines Work
In the past, all vaccines worked by introducing some part of a bacteria, virus, or pathogen into your body to trigger an immune response. Some of the vaccines developed for COVID-19 use a different approach.
Some of the vaccines available are mRNA vaccines. mRNA stands for messenger ribonucleic acid. mRNA carries genetic code from DNA for protein synthesis. Instead of using a bacteria, virus, or pathogen, mRNA vaccines teach our cells how to make a protein that triggers an immune response and produces antibodies. COVID-19 has spike proteins that help it invade cells. mRNA vaccines give instructions for our cells to make a piece of the spike protein. This piece of the spike protein is harmless and does not cause COVID-19. This protein is recognized by our immune system and allows us to produce an antibody response. The result is that you have some immunity since your body can recognize and hopefully fight off COVID-19 in the future.
A huge benefit of using mRNA technology is these vaccines can be created more rapidly than other methods. This is one reason we have developed COVID-19 vaccines more quickly than other vaccines in the past. mRNA technology is exciting, and hopefully, this will be a huge success story and pave the way for how all future vaccines are produced. mRNA vaccines have been studied for decades, but none have ever been approved for use until now. The risk is that this is a relatively new technology, and we lack long-term data on safety. mRNA vaccines never enter the nucleus of a cell and cannot cause genetic changes to your DNA.
Viral Vector Vaccines
Another newer technology utilized in some COVID-19 vaccines is a viral vector. These vaccines use a modified version of a different virus to deliver instructions to our cells to produce a spike protein for COVID-19. According to the CDC, vaccines that use the same viral vector have been given to pregnant people in all trimesters of pregnancy, including in a large-scale Ebola vaccination trial. No adverse pregnancy-related outcomes, including adverse outcomes that affected the infant, were associated with vaccination in these trials.
Recommended Vaccines During Pregnancy
Before COVID-19, only the Tdap and flu vaccines were routinely recommended during pregnancy. Expecting mothers are underrepresented in clinical research. This underrepresentation is partly due to the complexity of pregnancy and the vulnerability of developing babies. As COVID-19 has continued to impact pregnant mothers worldwide, there has been more attention to the need to include expecting mothers in clinical research.
COVID-19 Vaccines During Pregnancy
The American College of Obstetricians and Gynecologists practice advisory updated 3/24/2021 recommends that COVID-19 vaccines should not be withheld from pregnant individuals and should be offered to lactating individuals similar to non-lactating individuals. Individuals considering a COVID-19 vaccine should have access to available information about the safety and efficacy of the vaccine, including information about data that is not available.
The World Health Organization recommends the COVID-19 vaccine for pregnant women at high risk of exposure or who have comorbidities that add to their risk. Their position states, “Based on what we know about these vaccines, we don’t have any specific reason to believe there will be risks that would outweigh the benefits of vaccination for pregnant women. While pregnancy puts women at higher risk of severe COVID-19, very little data are available to assess vaccine safety in pregnancy. For this reason, those pregnant women at high risk of exposure to SARS-CoV-2 (e.g., health workers) or who have comorbidities which add to their risk of severe disease may be vaccinated in consultation with their health care provider.”
When to Get the COVID-19 Vaccine During Pregnancy
There are no specific guidelines as to an ideal timeframe during pregnancy to get the COVID-19 vaccine. You may receive the other vaccines recommended during pregnancy (Tdap and flu) at any time. ACOG does recommend that you do not get the COVID-19 vaccine within 14 days of another vaccine. Some expecting mothers and care providers may choose to avoid vaccines during the first trimester because this period is so critical to development. If you want to get the COVID-19 vaccine, please talk to your doctor or midwife about the timing.
COVID-19 vaccines are new, and manufacturers are producing them as quickly as possible to meet demand. Since supply is limited, the CDC has released guidelines on who should be eligible to receive the vaccine. Vaccine availability differs by state; to find the site for your state, click here. The CDC prioritized health care professionals and long-term care residents first. The next phase included frontline essential workers and people over the age of 75. As of March 26, 2021, we are in phase 1c, which includes people over age 65, people 16-64 with underlying medical conditions, and expanded frontline workers to include groups like the financial sector, IT, public safety, food service, etc. Pregnancy is an underlying medical condition that puts you at a higher risk for severe disease, which means if you want the vaccine, you should be able to get it.
Developing Vaccine Antibodies During Pregnancy
Once you get the COVID-19 vaccine, it takes your body about two weeks to develop antibodies. Some of the vaccines require two doses to ensure your body produces enough antibodies for adequate protection from the virus. When you are pregnant, you pass antibodies to your baby through the placenta. In a study that included 84 pregnant women, vaccine-generated antibodies were present in all umbilical cord blood samples. Since research is moving quickly and there is an urgent need for data, this study has not gone through the peer-review process. We can expect more data and these initial results are promising. Passing antibodies to your baby in utero or via breastmilk is called passive immunity. The goal when you get a vaccine during pregnancy is to protect both you and your baby. This is also valuable at a time when COVID-19 vaccines are not available for infants or children.
Passing Antibodies in Breastmilk
After your baby is born, you also continue to pass antibodies to them through your breastmilk. In the same study mentioned above, breastmilk samples from 31 lactating mothers who received a COVID-19 vaccine also showed vaccine-generated antibodies. I cannot stress enough the importance of breastfeeding, especially during the first few months of your baby’s life. This is whether or not you decide to get the COVID-19 vaccine. Even if your baby is getting formula and every meal isn’t breast milk, those antibodies you pass when you do breastfeed are amazing. Breastfeeding will significantly improve your newborn’s immune system and help to keep them healthier.
Different Vaccines Available
There are several different vaccines available now and more in the pipeline. The general push from the medical community is that the best vaccine is the one that is available to you now. ACOG states there is currently no preference for using one COVID-19 vaccine over another except for 16-17-year-olds who are only eligible for the Pfizer-BioNtech vaccine. Individuals should receive any product made available to them and be confident in the vaccine’s ability to provide a high level of protection from COVID-19 illness. The CDC urges that you get any COVID-19 vaccine available when you are eligible and not wait for a specific brand. Even so, if you prefer one brand over another, you can seek out that vaccine. The CDC has a vaccine finder tool that allows you to search based on vaccine brand. Availability may vary based on your doctor of the facility where you are vaccinated.
Types of COVID-19 Vaccines
There is a link to the manufacturer’s fact sheet for each of the vaccines, which contains a lot of data about the vaccine and the clinical trials. All vaccines currently approved are through the FDA’s EUA (emergency authorization use). For all of the vaccines, manufacturers state if you are pregnant or breastfeeding, discuss your options with your healthcare provider.
- EUA Approval: December 2020 in the U.S. for individuals 18 years of age and older
- Type of vaccine: mRNA
- Doses: two doses, one month apart
- Clinical Trials: Three clinical trials involving 30,351 participants, of which 15,419 received at least one dose of the Moderna vaccine.
- Vaccine efficacy: 94.1%
- Adverse reactions: pain at the injection site 92.0%, fatigue 70.0%, headache 64.7%, myalgia (muscle pain) 61.5%, arthralgia (joint pain) 46.4%, chills 45.4%, nausea/vomiting 23.0%, axillary (armpit) swelling/tenderness 19.8%, fever 15.5%, swelling at the injection site 14.7%, and erythema (redness) at the injection site 10.0%. These figures include adverse reactions for all doses. All adverse reactions increased from the first to the second dose.
- Serious Adverse Events: Two serious adverse events of facial swelling in vaccine recipients with a history of injection of dermatological fillers. The swelling was likely related to vaccination.
- Throughout the same period, there were three reports of Bell’s palsy in the Moderna COVID-19 Vaccine group (one of which was a serious adverse event) and one in the placebo group. Currently, available information on Bell’s palsy is insufficient to determine a causal relationship with the vaccine.
- Ingredients: a total lipid content of 1.93 mg (SM-102, polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG], cholesterol, and 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC]), 0.31 mg tromethamine, 1.18 mg tromethamine hydrochloride, 0.043 mg acetic acid, 0.12 mg sodium acetate, and 43.5 mg sucrose. Moderna COVID-19 Vaccine does not contain a preservative and vial stoppers are latex-free.
- Cases of severe COVID-19: no cases of severe COVID-19 were reported in the Moderna COVID-19 Vaccine group compared with 30 cases reported in the placebo group.
- Research relating to pregnancy: In a developmental toxicity study, 0.2 mL of a vaccine formulation containing the same quantity of nucleoside-modified messenger ribonucleic acid (mRNA) (100 mcg) and other ingredients included in a single human dose of Moderna COVID-19 Vaccine was administered to female rats by the intramuscular route on four occasions: 28 and 14 days prior to mating, and on gestation days 1 and 13. No vaccine-related adverse effects on female fertility, fetal development, or postnatal development were reported in the study.
- EUA Approval: December 2020 in the U.S. for individuals 16 years of age and older
- Type of vaccine: mRNA
- Doses: two doses, three weeks apart
- Clinical Trials: Two clinical trials involving 44,600 participants, of which 21,918 received at least one Pfizer vaccine dose.
- Vaccine efficacy: 95%
- Adverse reactions: pain at the injection site 84.1%, fatigue 62.9%, headache 55.1%, myalgia (muscle pain) 38.3%, arthralgia (joint pain) 23.6%, chills 31.9%, nausea/vomiting 1.1%, lymph node swelling/tenderness 0.3%, fever 14.2%, swelling at the injection site 10.5%, erythema (redness) at the injection site 9.5%, and malaise (generally feeling unwell) 0.5%. These figures include adverse reactions for all doses. All adverse reactions, except pain at the injection site, increased from the first to the second dose.
- Serious Adverse Events: Appendicitis was reported as a serious adverse event for 12 participants, numerically higher in the vaccine group, eight vaccine participants, and four placebo participants. Currently, available information is insufficient to determine a causal relationship with the vaccine. Bell’s palsy (facial paralysis) was reported by four participants in the Pfizer-BioNTech COVID-19 Vaccine group. No cases of Bell’s palsy were reported in the placebo group. Currently, available information is insufficient to determine a causal relationship with the vaccine.
- Ingredients: Vaccine contains 30 mcg of a nucleoside-modified messenger RNA (modRNA) encoding the viral spike (S) glycoprotein of SARS-CoV-2. Each dose of the Pfizer-BioNTech COVID-19 Vaccine also includes the following ingredients: lipids (0.43 mg (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate), 0.05 mg 2[(polyethylene glycol)-2000]- N,N-ditetradecylacetamide, 0.09 mg 1,2-distearoyl-sn-glycero-3-phosphocholine, and 0.2 mg cholesterol), 0.01 mg potassium chloride, 0.01 mg monobasic potassium phosphate, 0.36 mg sodium chloride, 0.07 mg dibasic sodium phosphate dihydrate, and 6 mg sucrose. The diluent (0.9% Sodium Chloride Injection, USP) contributes an additional 2.16 mg sodium chloride per dose. The Pfizer COVID-19 Vaccine does not contain a preservative. The vial stoppers are not made with natural rubber latex.
- Research relating to pregnancy: In a reproductive and developmental toxicity study, 0.06 mL of a vaccine formulation containing the same quantity of nucleoside-modified messenger ribonucleic acid (mRNA) (30 mcg) and other ingredients included in a single human dose of Pfizer-BioNTech COVID-19 Vaccine was administered to female rats by the intramuscular route on four occasions: 21 and 14 days prior to mating, and on gestation days 9 and 20. No Revised: February 25, 2021, 26 vaccine-related adverse effects on female fertility, fetal development, or postnatal development were reported in the study.
- EUA Approval: February 2021 in the U.S. for individuals 18 years of age and older
- Type of vaccine: viral vector
- Doses: one dose
- Clinical Trials: One clinical trial involving 44,325 participants, of which 21,895 received at least one dose of the Janssen vaccine.
- Vaccine efficacy: 66.1% Based on 39,321 participants, 19,630 that received the vaccine
- Adverse reactions: Safety was analyzed from a subset of 6,736 participants of the total trial participants, 3,356 who received the vaccine. Pain at the injection site 48.6%, fatigue 38.2%, headache 38.9%, myalgia (muscle pain) 33.2%, nausea/vomiting 14.2%, fever 9.0%, swelling at the injection site 5.3%, and erythema (redness) at the injection site 7.3%.
- Serious Adverse Events: One report of severe pain in the injected arm, not responsive to analgesics, with immediate onset at the time of vaccination, ongoing 74 days following vaccination, likely related to the vaccine. Six events of deep vein thrombosis in the vaccination group vs. 2 in the placebo group. 4 cases of pulmonary embolism vs. one event in the placebo group. One event of transverse sinus thrombosis. There were four seizures in the vaccine group vs. 1 in the placebo group. Six events of tinnitus in the vaccine group. For these events, a causal relationship with the Janssen COVID-19 vaccine cannot be determined.
- Ingredients: n 5×1010 virus particles (VP) and the following inactive ingredients: citric acid monohydrate (0.14 mg), trisodium citrate dihydrate (2.02 mg), ethanol (2.04 mg), 2-hydroxypropyl-β-cyclodextrin (HBCD) (25.50 mg), polysorbate-80 (0.16 mg), sodium chloride (2.19 mg). Each dose may also contain residual amounts of host cell proteins (≤0.15 mcg) and/or host cell DNA (≤3 ng). Janssen COVID-19 Vaccine does not contain a preservative, and the vial stoppers are latex-free.
- Cases of severe COVID-19: 2 instances of COVID-19 requiring hospitalization were reported in the Janssen COVID-19 Vaccine group compared with 29 cases reported in the placebo group. As of 1/22/2021, there were no COVID-19 related deaths in the vaccine group and five in the placebo group.
- Research relating to pregnancy: In a reproductive developmental toxicity study, female rabbits were administered 1 mL of the Janssen COVID-19 Vaccine (a single human dose is 0.5 mL) by intramuscular injection seven days prior to mating and on Gestation Days 6 and 20 (i.e., one vaccination during early and late gestation, respectively). No vaccine-related adverse effects on female fertility, embryo-fetal or postnatal development up to Postnatal Day 28 were observed.
More vaccines in development and trials may receive emergency use authorization for approval in the future.
- EUA Approval: Not approved in the U.S. The AstraZeneca vaccine is approved in some countries in the European Union.
- Type of vaccine: Like an mRNA vaccine, this gives cells instructions to make a piece of the spike protein but instead uses DNA from a chimpanzee adenovirus.
- Doses: Two doses, four to twelve weeks apart
- Clinical Trials: Four ongoing clinical trials involving 23,745 participants, 12,021, received at least one dose of the AstraZeneca vaccine. Because of logistical constraints, the interval between dose one and dose 2 ranged from 3 to 23 weeks (21 to 159 days), with 86.1% of participants receiving their two doses within the interval of 4 to 12 weeks (28 to 84 days).
- Vaccine efficacy: 59.5% Based on 10,468 participants, 5,258 that received the vaccine.
- Adverse reactions: Pain at the injection site 63.7%, fatigue 53.1%, headache 54.2%, myalgia (muscle pain) 44%, arthralgia (joint pain) 26.4%, nausea/vomiting 21.9%, and fever 7.9%. Compared with the first dose, adverse reactions reported after the second dose were milder and reported less frequently.
- Serious Adverse Events: The AstraZeneca vaccine has been temporarily suspended in some countries based on reports of rare blood coagulation disorders in people who had received the vaccine. As of 3/17/2021, the WHO considers that the AstraZeneca vaccine’s benefits outweigh its risks and recommends that vaccinations continue.
- Ingredients: One dose (0.5 ml) contains: Chimpanzee Adenovirus encoding the SARS-CoV-2 Spike glycoprotein ChAdOx1-S*, not less than 2.5 × 108 infectious units * Produced in genetically modified human embryonic kidney (HEK) 293 cells and by recombinant DNA technology. This product contains genetically modified organisms (GMOs). The other excipients are L-histidine, L-histidine hydrochloride monohydrate, magnesium chloride hexahydrate, polysorbate 80 (E 433), sucrose, disodium edetate (dihydrate), water for injections.
- Cases of severe COVID-19: No hospitalizations due to COVID-19 occurred in the vaccine group, compared to 8 in the placebo group.
- Research relating to pregnancy: Animal reproductive toxicity studies have not been completed. Based upon results from the preliminary study, no effects are expected on the development of the fetus.
Novavax is still undergoing clinical trials, and preliminary results look promising.
Comparing Vaccine Options
The FDA cautions that clinical trials are conducted under widely varying conditions. Adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in another drug’s clinical trials. Plus, the rates of adverse effects in a clinical trial may not reflect the rates observed in the real world. Given that disclaimer, we can look at the rates of adverse effects from a 10,000-foot view to summarize how these vaccines stack up. You will find manufacturer data and many links to research throughout this article. Please feel free to dig deeper into the evidence and draw your own conclusions. This article only compares the three vaccines that currently have emergency use authorization in the United States.
Comparing Efficacy of COVID-19 Vaccines
In a perfect world, a vaccine would be 100% effective with zero side effects. The WHO and the FDA called for a minimum efficacy of 50% for COVID-19 vaccines. For example, if a vaccine is 50% effective, then taking the vaccine would reduce your chances of developing COVID-19 by 50%. In clinical trials, vaccine efficacy is measured by giving some participants the vaccine, some participants a placebo, then measuring how many people get the virus. In the Pfizer clinical trial with 43,661 participants, researchers waited for 170 people to test positive for COVID-19. Then they looked at who out of these 170 had received the vaccine or placebo. Of the 170, 8 (about 5%) had the vaccine, making the vaccine 95% effective in preventing COVID-19 infection.
Effectiveness is how well a vaccine works in the real world. We are hopeful that vaccine effectiveness will match the efficacy seen in clinical trials, and time will tell as we see more data. Effectiveness is measured by the CDC using many different methods. It is challenging to compare vaccine efficacy between different clinical trials, and it is not an apples-to-apples comparison. The Moderna and Pfizer vaccines both have a high efficacy rate of 94-95%. Although the Janssen vaccine’s efficacy is 66.1%, trials showed only 2 cases of COVID-19 requiring hospitalization in the vaccine group compared with 29 cases reported in the placebo group. There were no COVID-19 related deaths in the vaccine group and five in the placebo group. If vaccines can help prevent severe COVID-19 infections, hospitalizations, and deaths, it is a huge win.
Comparing Adverse Effects
There is always the possibility of a severe allergic reaction with any vaccine. This is rare, but it does happen. Looking at rates of adverse effects, they are highest with the Moderna vaccine, slightly lower with Pfizer, and lowest with Janssen. The Janssen trial included much fewer participants than the other two vaccines. The takeaway is that having an adverse effect like fever, muscle soreness, nausea, or pain or swelling at the injection site is common with all vaccines.
When looking at the severe adverse effects, if you have had dermatological fillers, I would talk to your doctor or midwife before getting the Moderna vaccine. There were two cases where vaccine recipients had fillers and experienced facial swelling likely related to vaccination. Both the mRNA vaccines (Moderna and Pfizer) had a few cases of Bell’s Palsy, but the information currently available is insufficient to determine a causal relationship with the vaccine. We will have to wait to find out if this was due to the vaccines.
The Pfizer and Janssen trials had events reported that were significant enough to disclose, but there is not enough information to determine a causal relationship to the vaccine. The Pfizer vaccine trial had 8 cases of appendicitis in the vaccine group and 4 in the placebo group. Janssen had more cases of blood clots in the vaccine group and four seizures in the vaccine group vs. 1 in the placebo group. Plus, six cases of tinnitus (ringing in your ears) in the vaccine group. As these trials continue and more people get these vaccines, we will hopefully see more data to establish if these outcomes result from the vaccines. If these are due to the vaccines, we should have better numbers in the future of the risk of experiencing these outcomes.
The Research on the Safety of COVID-19 Vaccines During Pregnancy
Because these vaccines are so new, we have limited data on their safety during pregnancy. The initial clinical trials done to get the vaccines approved for use did not include pregnant participants. This is common in a lot of research. Some participants in the trials became pregnant after receiving the vaccine, and the CDC is monitoring these participants and tracking data.
A study of 84 pregnant women who got the Moderna or Pfizer vaccine. 11 were in the first trimester, 39 in the second trimester, and 34 in the third trimester. There was one preterm birth from a woman who went into labor at 35 weeks. The baby born preterm, and one additional baby was admitted to NICU. Otherwise, there were no adverse outcomes reported. The rate of babies born before 37 weeks in the U.S. is 10%, and one study found the NICU admission rate for low-risk women to be between about 6-9%. When we compare these rates, we would expect to see in the population compared to the outcomes in this study. It doesn’t look like the vaccine had a negative effect on the participants in this study, for the data reported.
All three vaccines that currently have emergency use authorization completed studies in animals before moving to human trials. Toxicity studies by Moderna, Pfizer, and Janssen gave animals vaccines before becoming pregnant and during pregnancy. There were no vaccine-related adverse effects on female fertility, fetal development, or postnatal development. These studies were on rabbits and rats, not humans, but it is promising that researchers found no adverse effects.
Even though we have limited data now, there is more in the pipeline. Pfizer is conducting a trial to study the vaccine in pregnant women. This includes about 4,000 healthy pregnant women who will receive the vaccine between 24-34 weeks. Harvard is starting a study soon that expects to include 5,000 pregnant women who receive the vaccine. It will be some time before we have results, but more research is underway.
No Evidence Links the Vaccines to Infertility
According to ACOG, Unfounded claims linking COVID-19 vaccines to infertility have been scientifically disproven. ACOG recommends vaccination for all eligible people who may consider future pregnancy. The mRNA vaccines never enter the nucleus of a cell and cannot cause genetic changes to your DNA. If you are trying to conceive or think you may want children in the future, there is currently no evidence the vaccines would negatively affect infertility.
Contribute to Future Research
If you are pregnant and receive a vaccine for COVID-19, you have an opportunity to participate in research that will help future expecting mothers. The CDC has a smartphone-based tool (v-safe) that uses text messages and web surveys to collect data after vaccinations. You are eligible to participate if you receive a vaccine within 30 days before conceiving or during pregnancy. The v-safe pregnancy registry is tracking this information and will help us have more data on the safety and efficacy of COVID-19 vaccines during pregnancy in the future. Please consider registering; your participation is voluntary, and you can opt-out at any time.
Fevers and Antipyretics
Fever is a common side effect of all of the available COVID-19 vaccines. In the clinical trials for the three approved vaccines, it ranged from 9-15%. According to the American College of Obstetricians and Gynecologists, pregnant women who experience fever following vaccination should be counseled to take acetaminophen. Acetaminophen has been proven to be safe for use in pregnancy and does not appear to impact antibody response to COVID-19 vaccines.
Acetaminophen is an antipyretic, which is a medication that can reduce a fever. There is a past episode of the podcast about fevers in pregnancy and the use of acetaminophen. There is some research challenging the use of acetaminophen during pregnancy, and you can learn more in this episode. If you plan to get a COVID-19 vaccine, talk to your doctor or midwife about how to treat fever and whether to take any antipyretic.
Other considerations for COVID-19 Vaccines
As you are weighing the risks and benefits of the COVID-19 vaccine during pregnancy, there are a few additional points you may want to consider. Regardless of whether you get the COVID-19 vaccine, you should be limiting your risk of exposure. It is still possible to get the virus even after vaccination. Some hospitals and birth centers may restrict whether you can have your partner or a support person present if you test positive for COVID-19. This is another reason you may consider the vaccine and be cautious about limiting your exposure to COVID-19.
COVID-19 has impacted everyone, and there is a massive campaign globally to get as many people as possible vaccinated. For many people, a vaccine is a key to going back to “normal life” again and having peace of mind that they have some protection.
Since the vaccines for COVID-19 are new, we do not know the duration of protection against COVID-19. If you already had COVID-19, your body does produce antibodies. However, we do not know for how long. The recommendation is to get the vaccine even if you already had COVID-19.
Effects of Vaccination on Transmission and Herd Immunity
Herd immunity occurs when a large percentage of the population is vaccinated. In effect, it protects the whole population, especially those who cannot receive vaccines. Herd immunity is an essential part of eradicating a contagious disease. One of the essential aspects of herd immunity is that it protects people who cannot develop immunity. This includes children who are too young for a vaccine and people who cannot receive a vaccine because of a medical reason. Herd immunity against COVID-19 is one of the goals of vaccination. In addition to contributing to herd immunity, initial data shows vaccines can reduce the infectious period’s duration and the pathogen load.
Talk to Your Doctor or Midwife
It can be frustrating not to have all the data right now. You can only make the best decision for yourself now, given the information you have. Please talk to your doctor or midwife about the COVID-19 vaccine. If you have concerns, bring them up. Please discuss any questions, no matter how small or silly they may seem. Your doctor or midwife is your trusted partner during your pregnancy. They bring a lot of knowledge and experience to help guide you through these decisions.
What to Expect If You Get the Vaccine
Before your appointment, talk to your doctor or midwife about what to do if you get a fever. For more information about fevers during pregnancy, see this episode.
At your appointment, you will get a shot in your upper arm with the COVID-19 vaccine. Pain and swelling at the injection site are common. You may be asked to stick around for about 15 minutes after the shot to monitor for immediate adverse or allergic reactions.
In the days following the vaccine, if you experience any side effects and have any questions or concerns, please contact your doctor or midwife. Mild side effects are common and if you feel fatigued or under the weather, give yourself time to rest and recuperate. Please consider participating in the CDCs v-safe registry to share information that can benefit pregnant mothers by having more data in the future.
Thank you to the amazing companies that have supported this episode.
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