Common Questions About Vaccination in Pregnancy

Find evidence-based information to answer your questions and support your decisions around vaccination in pregnancy.

Quick Facts

  • Pregnant people are at higher risk of serious illness.

    Changes in your heart, lungs, and immune system during pregnancy make you more likely to get seriously ill from infections like the flu compared to someone who is not pregnant.

  • Young babies are at higher risk of serious illness.

    Babies are especially vulnerable to serious illness from infections like RSV, pertussis (whooping cough), and flu during their first few months of life.

  • Vaccination during pregnancy helps protect you.

    Getting vaccinated during pregnancy lowers your risk of serious illness and hospitalization from common infections like the flu and COVID-19.

  • Vaccination during pregnancy helps protect your baby.

    When you get vaccinated during pregnancy, your body makes protective antibodies that pass to your baby through the placenta—helping protect them from serious illness in their first months of life.

  • The vaccines recommended in pregnancy are safe.

    Real-world evidence from millions of pregnant people shows that these vaccines are safe and do not increase the risk of miscarriage, birth defects, or other complications.

  • Talk to your healthcare provider about timing.

    Some vaccines are given at specific points in pregnancy, while others can be given anytime. Your healthcare provider can help you know what’s recommended and where to get it.

Which Vaccines Are Recommended in Pregnancy?

  • Influenza (Flu) Vaccine

    The flu shot is recommended during any trimester of pregnancy. It protects you from getting very sick with the flu and helps protect your baby after birth.

    Learn More

  • Tdap Vaccine

    The Tdap vaccine is given between 27 and 32 weeks of pregnancy. It protects your baby from pertussis (whooping cough) in the first few months of life.

    Learn More

  • COVID-19 Vaccine

    A COVID-19 vaccine is recommended during any trimester of pregnancy to protect you from serious illness and help protect your baby after birth.

    Learn More

  • RSV Vaccine (RSVpreF)

    The RSV vaccine is given between 32 and 36 weeks of pregnancy. It helps protect your baby from serious RSV illness in the first few months of life.

    Learn More

Understanding Vaccines

  • The immune system

    Your immune system is your body’s natural defence system. It’s made up of organs, cells, and proteins that work together to protect you from harmful germs like viruses and bacteria.

    • When a new germ (virus or bacteria) enters your body, your immune system responds by making proteins called antibodies, which help find and destroy the germ.

    • The first time your body encounters a new germ, your immune system needs time to figure out how to respond and start making antibodies. During this time, you might get sick.

    • Once your immune system learns how to fight the germ, it usually remembers it. If the same germ enters your body again, your immune system can recognize it quickly and respond fast enough to destroy it before it has a chance to make you sick.

    Where do vaccines come in?

    Vaccines give your immune system a safe “practice run” by showing it a harmless version or piece of a germ. This teaches your body how to recognize and fight the germ without the risk of getting sick first.

    • Many vaccines, like flu and Tdap vaccines, use tiny, inactivated (dead) or weakened pieces of the germ called antigens. These antigens can’t make you sick, but they help your immune system learn what to look out for. Other vaccines, like mRNA COVID-19 vaccines, give your body the instructions to make the antigen on its own.

    • After you get a vaccine, your immune system treats the antigen as if it were the real germ. It responds by making protective antibodies to fight against it. It also creates memory cells that stay in your body and help your immune system quickly recognize and respond if you're exposed to the real germ in the future. This fast response helps destroy the germ before it has a chance to make you sick.

    Some vaccines provide long-lasting protection, working for many years or even decades. Others protect you for a shorter time and may need additional “booster” shots to keep your immunity (protection) strong.

  • Vaccines teach your body how to recognize and fight off germs, but they do this in different ways depending on how they’re made.

    Inactivated vaccines

    • Inactivated vaccines use a dead germ or pieces of the germ, called antigens. Because the germ is not alive, it can’t cause illness. You can think of these germs as being “switched off.”

    • These vaccines are safe to receive during pregnancy because they do not contain any live germs.

    • Common examples of inactivated vaccines include the flu vaccine and the Tdap vaccine, which protects against tetanus, diphtheria, and pertussis (whooping cough).

    Live and live-attenuated vaccines

    • Live and live-attenuated vaccines use a weakened form of the germ that is still alive but has been changed so it can’t cause disease in healthy people. Common examples include the MMR vaccine (for measles, mumps, and rubella) and the chickenpox (varicella) vaccine.

    • These vaccines are not routinely recommended during pregnancy due to a small theoretical risk to the developing baby. This means that based on how the vaccines work, there is a possibility they could affect the baby—but this has not been seen in real-life studies.

    • In fact, research shows that babies born to people who received a live or live-attenuated vaccine during pregnancy—often before knowing they were pregnant—do not have higher rates of birth defects or infections related to the vaccine.1

    • Getting one of these vaccines while pregnant is not a reason to consider ending a pregnancy.

    mRNA Vaccines

    • mRNA vaccines work differently than inactivated or live vaccines. Instead of giving your body a weakened or dead piece of a germ (called an antigen), mRNA vaccines provide instructions that help your body make the antigen on its own.

    • These vaccines are safe to receive during pregnancy because they do not contain any live germs. This means they cannot give you COVID-19 or harm you or your baby.

    • The Pfizer-BioNTech and Moderna COVID-19 vaccines are examples of mRNA vaccines.

    The vaccines recommended during pregnancy—flu, Tdap, mRNA COVID-19, and RSVpreF—do not contain any live germs and are safe for both pregnant people and their babies.

  • In Canada, the following vaccines are recommended for all pregnant individuals:

    These vaccines are safe to receive during pregnancy because they do not contain live germs. This means they cannot give you the disease or harm you or your baby. Studies show that getting vaccinated during pregnancy is safe and helps protect your baby in the first few months of life, when they are most vulnerable to getting very sick from infections.

    In some cases, other vaccines may be recommended during pregnancy—for example, if you're traveling or have certain health risks. Talk to your healthcare provider to find out which vaccines are right for you.

  • Vaccines teach your body to make protective antibodies that help fight off germs like viruses and bacteria. During pregnancy, these antibodies naturally pass through the placenta to your baby, giving them early protection against harmful germs until they’re old enough to get their own vaccines.

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When you get vaccinated during pregnancy, you pass protective antibodies to your baby, helping keep them safe from common infections after they are born.

What’s in a Vaccine?

Every ingredient in a vaccine plays an important role, either in creating the vaccine or helping to keep it safe and effective.¹

Each ingredient in a vaccine serves a specific purpose. Some ingredients help your immune system respond better to the vaccine, while others make sure the vaccine stays safe and effective during storage and use.¹ For example, vaccines usually contain certain ingredients to prevent contamination and to keep the vaccine effective over time.

All vaccine ingredients are carefully studied and proven to be safe in the small amounts used.¹ Health Canada strictly regulates all vaccine ingredients and has strict rules to make sure they are safe for everyone who receives them.

  • Antigens are the part of a vaccine that teaches your immune system how to recognize and fight off harmful germs. They are usually made from a killed or weakened virus or bacteria, or a small piece of it.3 Some vaccines, like mRNA COVID-19 vaccines, don’t contain the antigen itself but give your body instructions to make the antigen on its own.

    Antigens trigger your immune system to produce special proteins called antibodies. Antibodies recognize and attach to specific germs, helping your body find and destroy them. These antibodies stay in your body for some time and help protect you if you're exposed to the real germ in the future.

  • Adjuvants are substances added to some vaccines to help strengthen the body’s immune response to the vaccine.3 In other words, they help the vaccine work better.

    Not all vaccines contain adjuvants. The most commonly used adjuvants are salts called aluminum hydroxide, aluminum sulphate and potassium aluminum sulphate. They are commonly referred to as ‘alum.’

    • Aluminum is one of the most common elements on earth. It's in the air we breathe, the water we drink, the food we eat, and many health products.3

    • The amount of aluminum in vaccines is very small and doesn’t pose any health risks.4,5

    • In fact, the amount of aluminum contained in vaccines is smaller than the amount found naturally in other things children consume, such as breastmilk and formula.4,5

  • Preservatives are added to some vaccines to prevent contamination by harmful germs like bacteria or fungi. They help keep vaccines safe and effective.

    One of the most commonly used preservatives in vaccines is 2-phenoxyethanol.6 It has been safely used for many years in many vaccines and is also found in several everyday baby care products and cosmetics.6

  • Stabilizers help prevent vaccine ingredients from breaking down (spoiling) while vaccines are being made, stored, and transported.3 Common stabilizers include sugars, salts, or oils, which are also found in everyday foods.

  • Residues are tiny traces of substances that may remain in a vaccine after it's made. Most of these are removed during the manufacturing process, but very small amounts can sometimes remain. These tiny traces are not harmful. In fact, many of them are already found naturally in our bodies.

    • For example, some vaccines may contain a very small amount of formaldehyde, which is used during manufacturing to help inactivate (or "kill") viruses and bacteria so they can be safely used in the vaccine.3

    • Our bodies actually produce more formaldehyde on their own than what's found in any vaccine.3

  • The diluent used in vaccines is usually sterile water or saline (salt water). It has no active ingredients and no effect on the body. Diluents are added to vaccines to help deliver the correct dose in a safe and effective way. In fact, most of what’s in a vaccine is water or saline.

    • You can find a table with a list of the ingredients used in vaccines approved in Canada in Part 1 of the Canadian Immunization Guide

    • You can find a list of ingredients included in each COVID-19 vaccine approved for use in Canada on the Government of Canada website

    • You can also find a list of vaccine ingredients in the vaccine's product monograph, which are available through Health Canada's Drug Product Database

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Getting vaccinated helps protect you and your baby from infections like the flu, COVID-19 and pertussis (whooping cough).

Vaccine Safety

  • Vaccines are some of the most carefully tested and closely monitored medical products in Canada. Before a vaccine is approved, it goes through a detailed and multi-step process to make sure it’s safe, effective, and high quality.7,8 This process includes testing in the lab, multiple phases of clinical trials in people, and a thorough review by Health Canada. Even after a vaccine is approved and in use, it continues to be monitored to catch any rare side effects and make sure it works as expected.

    Step 1: Lab Testing (Pre-Clinical Phase)  

    Before vaccines are tested in people, they go through careful studies in laboratories.Scientists first look at how the vaccine works and whether it could safely protect against a disease. If the results look promising, the vaccine is then tested in animals to check for any potential risks and to make sure it’s likely to be safe and effective.

    This phase also includes developmental and reproductive toxicity (DART) studies. These are special tests where the vaccine is given to animals before and during pregnancy. Researchers look at whether the vaccine affects fertility, causes problems during pregnancy, or impacts the health of the babies. These studies help provide important information about vaccine safety in pregnancy—before any testing is done in humans.

    Step 2: Human Testing (Clinical Trials)

    Once a vaccine passes lab and animal testing, it moves into clinical trials involving human volunteers. People who join a clinical trial are fully informed about the process and choose to take part voluntarily.

    Clinical trials happen in three phases. Each phase builds on the last, helping scientists understand more about how the vaccine works and making sure it's safe for larger and more diverse groups of people.9

    • Phase 1: A small group of healthy volunteers receives the vaccine to test basic safety, find the right dose, and identify common side effects.

    • Phase 2: The vaccine is given to hundreds of people to learn more about how well it works and to continue checking for side effects.

    • Phase 3: Thousands of people receive the vaccine to confirm its effectiveness and look for any rare or serious side effects.

    Step 3: Review and Approval by Health Canada

    Once all testing is complete, the vaccine manufacturer submits the data to Health Canada, the federal agency that regulates vaccines. Scientists at Health Canada carefully review all the evidence—including how the vaccine was made, how well it works, and how safe it is.9

    Health Canada only approves a vaccine if the evidence clearly shows that it is safe, effective, and meets high manufacturing standards.9 Approval is only granted if the benefits of the vaccine far outweigh any potential risks.9

    Step 4: Ongoing Monitoring After Approval

    Even after a vaccine is approved, its safety and effectiveness continue to be closely monitored.8,9 Scientists and health officials watch for:

    • How well the vaccine works in real-world settings

    • Any new, rare, or unexpected side effects

    Healthcare providers, vaccine manufacturers, and individuals can all report health issues that happen after vaccination. These reports go to systems like:

    This ongoing monitoring helps experts quickly spot and investigate potential safety concerns and take action if needed. Vaccine companies must also submit regular safety updates and real-world data to Health Canada to help ensure long-term safety and effectiveness.8,9

  • Yes, it’s possible—but that’s why vaccine safety is always being monitored, even after approval.

    Before a vaccine is approved, it’s tested in clinical trials with thousands of people. But some side effects are extremely rare and may not show up until the vaccine has been given to millions of people. That’s why safety checks continue long after a vaccine becomes available to the public. Canada has several systems in place to track and respond to any unexpected health events that might happen after vaccination.

    • An Adverse Event Following Immunization (AEFI) is any unexpected or unwanted change in health that happens after someone receives a vaccine.9

    • This could be something mild, like a sore arm or fever, or something more serious—though serious events are very rare.

    • It’s important to know that just because something happens after a vaccine, that doesn’t always mean the vaccine caused it. But every serious report is taken seriously and investigated by health experts to find out if there might be a connection.

  • In Canada, vaccine safety is closely monitored through a national surveillance system. This system involves several groups working together to track and respond to any unexpected health issues after vaccination:

    1. Healthcare providers are required to report any serious or unusual side effects they see in their patients.

    2. Provincial and territorial health authorities collect and review these reports from across their regions.

    3. The Public Health Agency of Canada (PHAC) gathers data from across the country and looks for patterns or safety concerns through systems like:

      • CAEFISS (Canadian Adverse Events Following Immunization Surveillance System), which monitors reports from public health authorities.

      • The Canada Vigilance Program, where individuals, healthcare professionals, and manufacturers can report possible side effects directly.

      • IMPACT (Immunization Monitoring Program ACTive), a pediatric hospital-based network that actively monitors serious adverse events following immunization in children.

    All this information is reviewed by medical experts and scientists. If any safety concerns are identified, Health Canada can act right away by updating safety guidance, changing how the vaccine is used, or in rare cases, stopping its use altogether.

  • Vaccines recommended during pregnancy—like the flu, Tdap, COVID-19, and RSVpreF vaccines—are safe for both you and your baby. Research shows that getting these vaccines while pregnant does not increase the risk of complications or health problems for you or your baby.

    Influenza (flu) vaccine:

    The flu vaccine is safe for pregnant people and for their babies. Research shows that getting the flu shot while pregnant does not increase the risk of complications. In people who got the flu shot during pregnancy, studies10-14 found:

    • No increased risk of preterm birth (before 37 weeks)

    • No increased risk of birth defects or miscarriage

    • No difference in average birth weight or due date

    • Lower rates of stillbirth compared to those who weren’t vaccinated

    Tdap (tetanus, diphtheria, pertussis) vaccine:

    The Tdap vaccine is safe for pregnant people and for their babies. In people who got the Tdap vaccine during pregnancy, studies15-17 found:

    • No increased risk of preterm birth (before 37 weeks)

    • No increased risk ofstillbirth or neonatal death (death in the first 28 days of life)

    • No increased risk of low birth weight or babies being small for gestational age

    • No increased risk of birth defects

    COVID-19 vaccines:

    mRNA COVID-19 vaccines, including all recommended booster doses, are safe for pregnant people and their babies. In people who got an mRNA COVID-19 vaccine during pregnancy, studies18-24 found:

    • No increased risk of preterm birth (before 37 weeks)

    • No increased risk of miscarriage orstillbirth

    • No increased risk of low birth weight or babies being small for gestational age

    • No increased risk of birth defects

    Maternal RSVpreF vaccine:

    Research shows that getting the RSV vaccine during the recommended time in pregnancy (32–36 weeks) does not increase the risk of complications or health issues in pregnant people or babies. Here’s what the research shows:

    • Early clinical trials found a slightly higher number of preterm (early) births in people who received the RSVpreF vaccine in some countries, including South Africa and Argentina. However, this difference wasn’t large enough to be considered “statistically significant” — meaning it could have happened by chance.25,26

    • What’s more, in countries like the United States, Canada, and across Europe, those same studies found no difference in the number of babies born early between people who got the vaccine and those who didn’t.25,27

    • We now have even more reassuring results from the first year the RSV vaccine was offered to pregnant people in the United States. A large safety study found that getting the vaccine between 32 and 36 weeks of pregnancy did not increase the risk of preterm birth or of babies being born smaller than expected.28

    • Another recent study looking at births during the 2023–2024 RSV season in the United States also found no difference in preterm birth rates between people who received the vaccine and those who didn’t.29 This study also found no increased risk of other complications, including stillbirth, jaundice, low blood sugar, or sepsis.29

    While any medication can come with potential risks, real-life data consistently show that the vaccines recommended during pregnancy are safe and effective for you and your baby. 

    It's natural to have questions about your health and your baby’s health, and making decisions about vaccination is an important part of your prenatal care. If you have concerns or want to learn more, talk to your healthcare provider. They can offer personalized advice based on the latest research and your individual circumstances.

  • No. The vaccines recommended during pregnancy, including flu, Tdap, RSV, and mRNA COVID-19 vaccines, will not make you or your baby sick. These vaccines do not contain any live viruses or bacteria, so they cannot cause the disease or harm you or your baby.

    Other vaccines that contain a live or weakened form of a virus or bacteria—known as ‘live’ or ‘live-attenuated’ vaccines—are generally not recommended during pregnancy because of a small, theoretical risk to the developing baby. But research shows that even when someone gets a live vaccine during pregnancy (often before knowing they are pregnant) their babies are not more likely to have birth defects or problems related to the vaccine.1 Accidentally receiving a live or live-attenuated vaccine is not a reason to consider ending a pregnancy. Examples of live vaccines include the measles, mumps, and rubella (MMR) vaccine and the chickenpox (varicella) vaccine.

Video: Vaccine safety assessment in pregnancy

Video provided courtesy of the Immunising Pregnant Women and Infants Network (IMPRINT). Explore more IMPRINT videos and resources here.

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Vaccine Reactions

  • Most people have no reaction to vaccination. Some have mild reactions that last between 12 and 24 hours and are easily treated at home. If your symptoms last longer than a couple of days, or if you are worried about how you feel after your vaccination, you can get help from your doctor or by calling the toll-free health information and advice phone service available in your province/territory:

    • British Columbia, Alberta, Saskatchewan, Ontario, Quebec, New Brunswick, Nova Scotia, Newfoundland and Labrador, New Brunswick, Prince Edward Island, the Yukon, the Northwest Territories: Call 811

    • Manitoba: Call 1-888-315-9257

    • Nunavut: Call 211

    You can also get help by visiting your nearest emergency department or urgent care centre. If you develop any serious symptoms that you think could be an allergic reaction after your vaccination, call emergency services right away by dialling 911.

  • The side effects that pregnant people may experience after vaccination are similar to those seen in adults who are not pregnant. Many people do not have any side effects at all. For those who do, the reactions are usually mild and go away on their own within a few hours or days.

    Common side effects after vaccination include soreness, redness, or swelling where the needle went in. Some people may also have muscle aches, joint pain, fever, or chills. These side effects are a normal part of your immune system’s response and show that your body is building protection against the disease. Most side effects are mild and go away on their own within a day or two.

    Soreness or redness at the injection site
    This usually improves within a day or two. To help with the discomfort, you can apply a cool, damp cloth to the area. If needed, you can take an over-the-counter pain reliever such as acetaminophen (Tylenol).

    Headache
    It’s common to have a mild headache after vaccination. This usually goes away on its own. If the headache is uncomfortable, you can consider taking some acetaminophen (Tylenol) to help you feel better.

    Mild fever
    A mild fever after vaccination is a normal sign that your body is building protection. To feel more comfortable, try resting, drinking plenty of fluids, and wearing light clothing. You can also consider taking acetaminophen (Tylenol) to help lower the fever. If you feel very unwell or your fever doesn’t go away, contact your healthcare provider.

    Always talk to your healthcare provider before taking any other medications.

  • Serious side effects from vaccines during pregnancy are very rare. In the rare cases where they do happen, they are usually treated quickly by healthcare professionals, and both the pregnant person and baby go on to make a full recovery.

    One example of a rare but serious reaction is a severe allergic reaction called anaphylaxis. This can cause symptoms like:

    • Swelling of the face or throat

    • Hives or rash

    • Trouble breathing

    • Low blood pressure

    • In very rare cases, shock

    Anaphylaxis is rare and only happens in about one in a million people who get a vaccine.30 When it does happen, it usually occurs within minutes after the vaccine is given. That’s why you are asked to stay at the clinic for a short time after your shot—so that trained healthcare providers can help right away if needed.

    If you ever experience serious symptoms after leaving the clinic, such as difficulty breathing or swelling in your face or throat, call 911 or go to the nearest emergency room immediately.

  • If your symptoms last longer than a couple of days, or if you are worried about how you feel after your vaccination, you can get help from your doctor or by calling the toll-free health information and advice phone service available in your province/territory:

    • British Columbia, Alberta, Saskatchewan, Ontario, Quebec, New Brunswick, Nova Scotia, Newfoundland and Labrador, New Brunswick, Prince Edward Island, the Yukon, the Northwest Territories: Call 811

    • Manitoba: Call 1-888-315-9257

    • For Nunavut: Call 211

    You can also get help by visiting your nearest emergency department or urgent care centre. If you experience any serious symptoms after vaccination, such as difficulty breathing or swelling in your face or throat, call 911 or go to the nearest emergency room immediately.

  • Most pregnant people can get safely vaccinated during pregnancy without experiencing any serious issues. While the vaccines recommended during pregnancy are safe for most people, there are a few situations where your healthcare may advise you not to get a specific vaccine:

    1. Severe allergy to a vaccine ingredient: If you’ve had a serious allergic reaction (anaphylaxis) to a previous dose of a vaccine or to a specific ingredient in the vaccine, you may be advised not to get that vaccine again. Talk with your healthcare provider about any allergies you may have and whether you’ve experienced a reaction to any vaccines before.

    2. Specific health conditions: In very rare cases, certain health conditions or treatments that affect the immune system may require a different vaccination plan. Your healthcare provider can guide you based on your medical history.

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Real-world evidence shows that vaccination is a safe and effective way to protect you and your baby from common infections.

Vaccine Myths vs. Facts

  • There is no evidence that COVID-19 vaccines cause fertility problems in anyone, regardless of gender.31-33 Research shows:

    • No link between COVID-19 vaccines and infertility
    • No increase in the risk of miscarriage or stillbirth
    • No difference in the chances of getting pregnant between people who are vaccinated and those who are not

    COVID-19 vaccines are safe for people who are trying to get pregnant now or in the future. If you have questions about fertility and vaccination, talk to your healthcare provider.

  • Some people who menstruate have reported temporary changes to their period after getting a COVID-19 vaccine. Research33-35 shows that these changes may include:

    • Periods that last longer than usual

    • Shorter time between periods

    • Heavier bleeding than usual

    These changes are typically mild and short-term, often returning to normal within one or two cycles.36

    Researchers are still studying why this happens, but the exact cause is not yet known. According to the Society of Obstetricians and Gynaecologists of Canada (SOGC), many things can affect your period, including stress, illness, sleep, diet, and exercise.36 Regardless of temporary changes in menstruation, there is no evidence that COVID-19 vaccination causes fertility problems.31-33

    Interestingly, what we do know is that COVID-19 infections can impact the menstrual cycle, and often for much longer than the vaccine.36

  • Some people wonder if getting sick and recovering provides better protection against a disease than vaccination. While this type of natural immunity can sometimes last longer, the risks of getting an infection during pregnancy are much higher than any potential risks from the vaccine.

    • For example, pregnant people are more likely to get very sick from COVID-19.

    • A COVID-19 infection during pregnancy can increase the risk of complications such as preterm birth (before 37 weeks) and stillbirth.37,38

    • On the other hand, serious side effects from the COVID-19 vaccine during pregnancy are very rare. Common side effects, such as a sore arm, headache, or mild fever, are usually short-lived and go away within a few days.

    • Even if you've already had COVID-19, getting vaccinated will give you an extra layer of protection against severe illness and hospitalization.

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  • 1.  Laris-González A, Bernal-Serrano D, Jarde A, Kampmann B. Safety of Administering Live Vaccines during Pregnancy: A Systematic Review and Meta-Analysis of Pregnancy Outcomes. Vaccines. 2020;8(1):124. https://doi.org/10.3390/vaccines8010124.

    2.  Chittajallu LVS, Kaku R, Kondadasula P, Lim JY, Zhumabekova A. Safety and Efficacy of Vaccines During Pregnancy: A Systematic Review. Cureus. 2025;17(1):e77176. 10.7759/cureus.77176.

    3.  HealthLink BC. Vaccine ingredients [Internet] Victoria, BC: Government of British Columbia; 2024 [updated Dec 5, 2024. Available from: https://www.healthlinkbc.ca/health-library/immunizations/information-and-safety/vaccine-ingredients.

    4.  Children's Hospital of Philadelphia. Vaccine Ingredients: Aluminum [Internet] Philadelphia, PA: Children's Hospital of Philadelphia; 2022 [updated Dec 15, 2022]. Available from: https://www.chop.edu/vaccine-education-center/vaccine-safety/vaccine-ingredients/aluminum.

    5.  Goullé JP, Grangeot-Keros L. Aluminum and vaccines: Current state of knowledge. Med Mal Infect. 2020;50(1):16-21. 10.1016/j.medmal.2019.09.012.

    6.  World Health Organization. How are vaccines developed? [Internet]: Gavi, the Vaccine Alliance; 2020 [updated Dec 10, 2020]. Available from: https://www.gavi.org/vaccineswork/how-are-vaccines-developed.

    7.  Healthlink BC. Development, approval, and safety monitoring  [Internet]: Government of British Columbia; 2024 [updated Dec 9, 2024]. Available from: https://www.healthlinkbc.ca/health-library/immunizations/information-and-safety/development-approval-and-safety-monitoring.

    8.  Health Canada. Regulating vaccines for human use in Canada [Internet] Ottawa, ON: Government of Canada; 2020 [updated Sept 9, 2020]. Available from: https://www.canada.ca/en/health-canada/services/drugs-health-products/biologics-radiopharmaceuticals-genetic-therapies/activities/fact-sheets/regulation-vaccines-human-canada.html.

    9.  Health Canada. Vaccine development and approval in Canada [Internet] Ottawa, ON: Government of Canada; 2021 [updated Apr 13, 2022]. Available from: https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/development-approval-infographic.html.

    10.  Fell DB, Platt RW, Lanes A, Wilson K, Kaufman JS, Basso O, et al. Fetal death and preterm birth associated with maternal influenza vaccination: systematic review. Bjog. 2015;122(1):17-26. 10.1111/1471-0528.12977.

    11.  McMillan M, Porritt K, Kralik D, Costi L, Marshall H. Influenza vaccination during pregnancy: a systematic review of fetal death, spontaneous abortion, and congenital malformation safety outcomes. Vaccine. 2015;33(18):2108-17. 10.1016/j.vaccine.2015.02.068.

    12.  Regan AK, Moore HC, de Klerk N, Omer SB, Shellam G, Mak DB, et al. Seasonal Trivalent Influenza Vaccination During Pregnancy and the Incidence of Stillbirth: Population-Based Retrospective Cohort Study. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2016;62(10):1221-7. 10.1093/cid/ciw082.

    13.  McHugh L, Andrews RM, Lambert SB, Viney KA, Wood N, Perrett KP, et al. Birth outcomes for Australian mother-infant pairs who received an influenza vaccine during pregnancy, 2012-2014: The FluMum study. Vaccine. 2017;35(10):1403-9. 10.1016/j.vaccine.2017.01.075.

    14.  Regan AK, Wesselink AK, Wang TR, Savitz DA, Yland JJ, Rothman KJ, et al. Risk of Miscarriage in Relation to Seasonal Influenza Vaccination Before or During Pregnancy. Obstet Gynecol. 2023;142(3):625-35.

    15.  McMillan M, Clarke M, Parrella A, Fell DB, Amirthalingam G, Marshall HS. Safety of Tetanus, Diphtheria, and Pertussis Vaccination During Pregnancy: A Systematic Review. Obstet Gynecol. 2017;129(3):560-73. 10.1097/aog.0000000000001888.

    16.  Panagiotakopoulos L, McCarthy NL, Tepper NK, Kharbanda EO, Lipkind HS, Vazquez-Benitez G, et al. Evaluating the Association of Stillbirths After Maternal Vaccination in the Vaccine Safety Datalink. Obstet Gynecol. 2020;136(6):1086-94.

    17.  Fakhraei R, Crowcroft N, Bolotin S, Sucha E, Hawken S, Wilson K, et al. Obstetric and perinatal health outcomes after pertussis vaccination during pregnancy in Ontario, Canada: a retrospective cohort study. CMAJ Open. 2021;9(2):E349.

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