Common Questions

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

  • Getting vaccinated in pregnancy is a safe and effective way to protect you and your baby from harmful germs and bugs.

  • Getting vaccinated in pregnancy gives your baby early protection against harmful germs until they are old enough to get their own vaccinations.

  • The vaccines recommended during pregnancy are safe and do not increase the risk of pregnancy or birth complications.

  • There is no chance that the vaccines recommended in pregnancy could make you or your baby sick because they don’t contain ‘live’ germs.

Understanding Vaccines

  • Vaccines play an important role in keeping us healthy by protecting us from harmful germs (viruses and bacteria). You can think of vaccines as training sessions for your immune system. They "coach" your body’s natural defences to recognize and fight off viruses and bacteria. Vaccines do this by giving your body a harmless “preview” of a germ, helping it learn to defend itself.

    • Many vaccines, like the flu (Influenza) and Tdap vaccines, use antigens to give this preview. Antigens are harmless versions or pieces of a germ that have been killed or inactivated ("switched off").

    • Other vaccines, like the mRNA COVID-19 vaccines, work by giving your body the instructions to make the antigens on its own.

    • When you get vaccinated, your body sees these antigens as unwelcome intruders and responds by creating protective antibodies and memory cells.

    • These antibodies and memory cells stay ready to fight off the real germ if you’re exposed to it in the future.

    Some vaccines provide long-term immunity (protection), lasting many years or even decades. Others offer protection for shorter periods and may require additional ('booster') shots to keep your immunity strong.

  • Vaccines teach your body how to recognize and fight off germs in different ways:

    1. Inactivated vaccines are made using a dead germ (or parts of it) called antigens. These antigens can’t make you sick because they aren’t alive. You can think of them as being “switched off” (killed). Inactivated vaccines are considered safe during pregnancy. Examples of inactivated vaccines include the influenza (flu) vaccine and the Tdap (tetanus, diphtheria, pertussis) vaccine.

    2. Live and live-attenuated vaccines are made using germs that are still alive but have been weakened. Generally, these weakened germs can’t cause disease in healthy people. However, these vaccines are not routinely recommended during pregnancy because of a small theoretical risk to developing babies. The risk to developing babies is theoretical because real-life data shows that babies born to a parent who got a live or live-attenuated vaccine during pregnancy (often without knowing they were pregnant) don’t have higher rates of birth defects or infections related to the vaccine. Getting a live or live-attenuated vaccine during pregnancy is not a reason to consider terminating (ending) a pregnancy.

    3. mRNA vaccines work differently than inactivated or live vaccines. Instead of giving you a weakened or dead version of the germ, mRNA vaccines give your body the instructions for making antigens on its own. The Pfizer-BioNTech and Moderna COVID-19 vaccines are examples of mRNA vaccines. mRNA COVID-19 vaccines are considered safe during pregnancy because they do not contain a ‘live’ virus. This means they can’t give you COVID-19 or cause any harm to you or your baby.

  • Getting vaccinated during pregnancy helps protect both you and your baby from harmful germs that can make you sick. In Canada, the following vaccines are recommended for all pregnant individuals:

    1. Influenza (flu) vaccine

    2. Tdap (tetanus, diphtheria, pertussis) vaccine

    3. mRNA COVID-19 vaccines

    4. In 2023, Health Canada also approved a maternal RSV vaccine (RSVpreF) to help prevent severe RSV infections in young babies.

    These vaccines are safe to receive during pregnancy because they don’t contain "live" germs, meaning they can’t give you the disease or harm you or your baby.

    • The flu and Tdap vaccines are examples of inactivated vaccines, which contain harmless, dead pieces of a germ. These pieces can’t cause illness.

    • mRNA COVID-19 vaccines, such as those from Pfizer-BioNTech and Moderna, are also recommended during pregnancy. Like inactivated vaccines, mRNA vaccines are safe for pregnant individuals because they don’t contain live viruses.

    • Vaccines made with "live" viruses, like the measles, mumps, and rubella (MMR) vaccine, are not recommended during pregnancy.

    In some cases, other vaccines may be recommended during pregnancy, such as when traveling or in special circumstances. Talk to your healthcare provider for more information on which vaccines are right for you.

  • Vaccines teach your body to make protective antibodies to fight germs like viruses or bacteria. During pregnancy, these protective antibodies pass to your baby through the placenta. This gives your baby early protection against harmful germs until they are old enough to get their own vaccines.

    It’s important to know that only the protective antibodies your body makes pass to your baby in significant amounts. These antibodies will protect your baby at birth and throughout the first few months when they need it the most and until they are old enough to get their own vaccines.

    Vaccine ingredients stay near the injection site, in your muscle and lymphatic system. Once the vaccine has finished training your immune system to recognize and fight off a germ, your body will naturally break down and get rid of the vaccine ingredients, just like it gets rid of other materials it no longer needs. The vaccine ingredients are out of your body after several weeks.

Watch: How do vaccines protect moms and babies?

What’s in a Vaccine?

Vaccine ingredients have been carefully studied and are safe in the small amounts used.¹ Every ingredient in a vaccine plays an important role, either in creating the vaccine or in ensuring its safety and effectiveness.¹

Health Canada closely regulates vaccine ingredients and has strict rules to make sure they are safe for people to receive.

  • The most important part of a vaccine is the antigen (a harmless version of a disease-causing germ or parts of the germ).¹ Some newer vaccines, such as mRNA COVID-19 vaccines, give your body the instructions to make the antigens on its own.¹ Antigens train your body to recognize bad germs and remove them from the body quickly before they can cause serious illness.

  • Adjuvants are substances added to some vaccines to help strengthen the body’s immune response to the vaccine (i.e., they help the vaccine work better).¹ 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.¹ The amount of aluminum in vaccines is very small and doesn’t pose any health risks. 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.²

  • Preservatives are used in some vaccines to protect them from becoming contaminated with harmful germs, like bacteria or fungi. One of the most common preservatives used in some vaccines is 2-phenoxyethanol, which can also be found in many cosmetics, baby care products, and eye and ear drops.³

  • Stabilizers help prevent vaccine ingredients from breaking down (spoiling) while vaccines are being made, stored, and transported.¹ Common stabilizers include sugars, salts, or oils, which are also found in everyday food.

  • Residues are tiny amounts of substances that remain in the vaccine after the manufacturing process. Most of these substances are removed from the final vaccine product, but small amounts may remain. In such tiny amounts, these residues are harmless, and most are already present in our bodies. For example, tiny traces of formaldehyde can be detected in some vaccines. Formaldehyde is used to inactivate (kill) viruses and bacteria so they can be safely used as antigens in vaccines. Human bodies naturally produce larger amounts of formaldehyde than found in vaccines.¹

  • The diluent used in vaccines is usually sterile water or saline (salt water). Diluents have no effect on the body. They are included in vaccines to ensure that the smallest useful dose can be used. Vaccines are mostly made up of water or saline.

  • mRNA COVID-19 vaccines work differently than the other vaccines recommended during pregnancy. Instead of giving you an inactivated (killed) version of the virus, these vaccines use Messenger RNA (mRNA). This mRNA is like a set of instructions that teaches your body how to make a harmless copy of a piece of the virus.

    • Coronaviruses, like the one that causes COVID-19, have crown-shaped spikes on their surface called spike proteins.⁴

    • The mRNA in the vaccine gives your cells the instructions for producing a harmless copy of the spike protein found on the surface of the COVID-19 virus. Once your cells have finished making the protein copies, your body identifies them as unwelcome intruders.

    • Your body responds by making protective antibodies and memory cells that will recognize and fight off the actual COVID-19 virus if you ever get it.

    • mRNA COVID-19 vaccines do not contain a live virus and cannot give you COVID-19.

    The other ingredients used in mRNA COVID-19 vaccines include sugars, salts, and lipids (fats). Many of these ingredients are commonly found in the everyday food we eat.⁵

    • Lipids (fats): Think of lipids as little protective bubbles. They surround the delicate mRNA to keep it safe. This means the mRNA doesn't break down too quickly once inside your body. Lipids also work together to help mRNA enter cells.⁵

    • Salt, sugar and acid stabilizers: These help keep the vaccine stable (in good condition) while it is produced, frozen, shipped, and stored.⁵

    After the vaccine has finished teaching your immune system how to defend against the COVID-19 virus, your body will naturally break down and get rid of the vaccine ingredients, just like it gets rid of other materials it no longer needs.⁵

    The following are NOT found in mRNA COVID-19 vaccines⁵:

    • NO preservatives, like thimerosal or mercury.

    • NO antibiotics of any kind.

    • NO tissues or materials from animals, including fetal cells or gelatin.

    • NO food proteins such as eggs, gluten, peanuts, or any nut products.

    • NO metals or manufactured products like microelectronics or nanowire semiconductors.

    • 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

Vaccines protect you and your baby from common infections that can be serious during pregnancy.

Vaccine Safety

  • Vaccines are among the most strictly regulated medical products in Canada.⁶

    All vaccines go through in-depth and rigorous testing processes and must pass through three phases of clinical trials to show that they are safe and effective before they are approved for use in Canada.⁶ Once vaccines are approved for use, they continue to be monitored for safety and effectiveness (how well they are working to protect individuals and the population). Any problems people might have after getting vaccinated are carefully tracked and looked into.⁷

    1. Pre-Clinical Phase (Lab Testing): Before any testing in humans, vaccines are studied in laboratories. If lab studies show that the vaccine has good potential to protect against a disease, they are then studied in animals. This helps researchers see if the vaccine is safe and effective and to spot any possible risks. This phase also involves developmental and reproductive toxicity (DART) studies, where the vaccine is tested in animals before and during pregnancy. These studies are used to determine if the vaccine has any negative effects on the animals' ability to reproduce (have babies), the pregnancy itself, or on the health and development of the babies. DART studies give us important information on the potential risks and safety of vaccines during pregnancy.

    2. Clinical Trials: If a vaccine is shown to be safe and effective in animals, it is then studied in humans. People taking part in these studies are volunteers who choose to participate in the research and are fully informed about the possible risks and benefits.⁶⁻⁷ There are three phases (stages) of clinical trials that study the safety and effectiveness of a vaccine in humans⁸:

      • Phase 1: A small group of healthy volunteers is given the vaccine to check its safety, figure out the right dose, and identify any major side effects.

      • Phase 2: The vaccine is given to a larger group (generally hundreds of people) to test how well it works, if it is safe in a larger number of people and learn more about the safest and most effective dose.

      • Phase 3: If the vaccine is effective and safe, it is then given to a much larger group (generally thousands of people) to confirm that it protects against the disease in large populations and to check for any uncommon or serious side effects.

    3. Review by Health Experts: Health Canada, a government agency, carefully reviews all the information from these tests to decide if the vaccine is safe, of high quality, and effective.⁷

    4. Approval: If the vaccine passes all of these tests and the review by Health Canada, it gets approval.⁷ Health Canada only approves a vaccine for use if it has been proven to be safe and effective and only if the benefits of the vaccine greatly outweigh any potential risks associated with it.⁷

    5. Ongoing Safety Checks: Even after a vaccine is approved, its safety and effectiveness are continuously monitored. Any problems people might have after getting the vaccine are tracked and looked into.⁷

    6. Reporting Problems: If someone has a problem after getting the vaccine, healthcare professionals or the public can report it to Health Canada. This is part of a program that helps identify if there are any safety issues that need further investigation.

    This step-by-step process is in place to make sure that vaccines used in Canada meet the highest safety and effectiveness standards.

  • During the COVID-19 pandemic, Health Canada made it a priority to approve vaccines quickly to get them to people as soon as possible. They did this by:

    1. Letting vaccine manufacturers submit their research data as soon as it was available, and

    2. Allowing Health Canada experts to review it immediately.⁹

    Importantly, this faster process did not mean that safety was overlooked. Vaccines were approved only after a complete and careful review of all the required safety data.⁹

    • Health Canada maintained its strict standards for vaccine review during this expedited process. This means each vaccine still had to be proven safe, effective, and of high quality before being approved by Health Canada.10

    • Vaccines were still required to go through in-depth clinical trials to confirm their safety and effectiveness.⁹ Health Canada only approved vaccines after receiving enough evidence that they were safe and effective.10-11

  • Once a vaccine is approved, its safety continues to be closely monitored. Sometimes, side effects are so rare that they aren't detected even when millions of people have received the vaccine.⁶ Because of this, monitoring for safety continues even after a vaccine is approved and widely used.

    Once it is in use, there are several systems in place to monitor a vaccine’s safety. Adverse (bad) reactions or events after vaccination are reported in each province and territory and are also reported to the Government of Canada. An Adverse Event Following Immunization (also known as an AEFI) is an unwanted or unexpected change in health that happens after someone receives a vaccine.12 Adverse events are tracked and studied carefully, and every serious event is reviewed in detail.

  • Health Canada and the Public Health Agency of Canada (PHAC) work together to identify and review any vaccine safety concerns.13 Health Canada and PHAC regularly review AEFI (adverse events following immunization) reports submitted to their databases. They also stay up to date by:

    • Regularly reviewing medical research.12

    • Tracking the work of other health agencies around the world.12

    • Following guidance from the World Health Organization Global Advisory Committee on Vaccine Safety (WHO GACVS).12

    Health Canada and PHAC will take appropriate action if they identify a new health risk tied to a vaccine. For example, Canada has clear laws and procedures in place to either recall a vaccine or stop the delivery of a specific batch if a serious safety concern is detected.14

  • The flu, Tdap, RSVpreF and mRNA COVID-19 vaccines are safe for pregnant people and their babies. Research shows that getting these vaccines during pregnancy does NOT increase the risk of complications (problems) during pregnancy or birth.

    Influenza (Flu) Vaccine:

    The flu vaccine is safe for pregnant people and for their babies. Studies15-19 show that for pregnant people vaccinated against the flu during pregnancy there was:

    • No increase in the risk of premature birth (birth before 37 weeks of pregnancy)

    • No increase in the risk of birth defects

    • No increase in the risk of miscarriage

    • No difference in average gestational age or birth weight

    • Lower rates of stillbirth among women who got the flu vaccine in pregnancy, compared to mothers who didn’t.

    Tdap (tetanus, diphtheria, pertussis) Vaccine:

    The Tdap vaccine is safe for pregnant people and for their babies. Specifically, a review of many studies20 confirmed that for pregnant people vaccinated against tetanus, diphtheria, and pertussis during pregnancy there was:

    • No increase in the risk of preterm birth (birth before 37 weeks of pregnancy)

    • No increase in the risk of stillbirth or neonatal death (death during the first 28 days of life)

    • No increase in the risk of babies that were small for gestational age

    • No increase in the risk of low birth weight (less than 2.5kg)

    • No increase in the risk of birth defects

    mRNA COVID-19 Vaccines:

    mRNA COVID-19 vaccines, including all recommended booster doses, are safe for pregnant people and their babies. Studies21-23 show that for pregnant people vaccinated against COVID-19 during pregnancy there was:

    • No increase in the risk of pregnancy loss (miscarriage)

    • No increase in the risk of preterm birth (birth before 37 weeks of pregnancy)

    • No increase in the risk of stillbirth

    • No increase in the risk of low birth weight

    On the other hand, we do know that getting a COVID-19 infection during pregnancy does increase the risk of these serious problems. Studies have shown that catching a COVID-19 infection during pregnancy can increase the risk of:

    • Preterm birth (birth before 37 weeks of pregnancy)

    • Low birth weight

    • Babies being admitted to a neonatal intensive care unit (NICU) with COVID-related complications.24

    Maternal RSVpreF Vaccine:

    The RSVpreF vaccine approved for use during pregnancy helps protect both you and your baby by reducing the risk of severe RSV infections.

    The approval process for the maternal RSVpreF vaccine was unique because it included pregnant individuals in the clinical trials. This provides strong evidence that the vaccine is safe and effective during pregnancy.

    Here’s what the studies show:

    • In studies conducted in Argentina and South Africa, preterm births (babies born before 37 weeks) occurred in 5.6% of pregnant people vaccinated between 24-36 weeks of pregnancy, compared to 4.7% of those who did not get the vaccine.10-12

    • When the vaccine was given during the recommended period of 32-36 weeks, preterm births occurred in 4.2% of vaccinated pregnant people compared to 3.7% of those unvaccinated.10-12 These small differences were not statistically significant, meaning they could have happened by chance.

    • It's important to know that in Canada, up to 8% of babies are born prematurely, which is the typical rate for the general population. This means the rates of preterm birth seen in the study are actually lower than what we see in real life.4

    • In other regions like Canada, the US, and Europe, there was no difference in the rate of preterm births between those who received the RSVpreF vaccine and those who didn’t.4,13

    • There is also no evidence that the RSVpreF vaccine affects future fertility or increases the risk of miscarriage.4,13

    While any medication can come with potential risks, real-life data consistently shows that the vaccines recommended during pregnancy are both safe and effective for protecting you and your baby. It's natural to have questions about your health and your baby’s health, and making decisions about vaccines 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. There is no risk that the flu, Tdap, RSVpreF or mRNA COVID-19 vaccines recommended in pregnancy will make you sick because they don’t contain a ‘live’ germ (virus or bacteria). This means that they can’t give you the disease or harm you or your baby in any way.

    On the other hand, live or live-attenuated vaccines containing ‘live’ viruses or bacteria pose a theoretical risk to a developing baby and are not routinely recommended in pregnancy. The risk to developing babies is ‘theoretical’ because real-world data shows that babies born to a parent who got a live or live-attenuated vaccine during pregnancy (often without knowing they were pregnant at the time) don’t have higher rates of birth defects or infections related to the vaccine. This means that accidentally getting a live or live-attenuated vaccine during pregnancy is not a reason to consider terminating (ending) a pregnancy. Examples of live vaccines include measles, mumps, and rubella (MMR) and Varicella (chickenpox).

    Talk to your healthcare provider about which vaccines are safe and recommended for you during pregnancy.

Watch: Vaccine safety assessment in pregnancy

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

Questions are a natural part of your pregnancy journey. Real-world evidence shows that vaccination during pregnancy is a safe and effective way to protect both you and your baby.

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 reactions pregnant people have to vaccination are similar to those of adults who are not pregnant. Many people have no reaction at all, while others may experience some temporary side effects that usually last from a few hours to a few days after vaccination.

    Common side effects after a vaccine include soreness, redness, and swelling where the vaccine was given, muscle or joint pain, fever, and/or chills.²⁵ These side effects are caused by your immune system's normal response to the vaccine and are usually quite mild, often going away on their own within a day or two.

    • Redness or soreness at the spot where the needle went in: The redness and soreness should start to feel better in a day or two. While you're waiting, you can use a cool, damp cloth on the area to help soothe it or take an over-the-counter pain medication like acetaminophen (Tylenol) if you need to.

    • Headache: The headache is likely to improve on its own, but if you feel the need for relief, you can consider taking an over-the-counter pain medication, such as acetaminophen (Tylenol).

    • Mild Fever: If you have a fever after your vaccination, drink plenty of water and consider using some acetaminophen (Tylenol) to help bring the temperature down.

    Always make sure to check with your healthcare provider before taking any other pain medications.

  • Research shows that the flu, Tdap, and mRNA COVID-19 vaccines recommended in pregnancy do not increase the risk of pregnancy complications like miscarriage, premature birth, or stillbirth. Serious reactions to vaccination during pregnancy are also very rare. When they do happen, they are usually resolved with treatment from healthcare professionals or at a hospital, with both mother and baby returning to full health.

    A very small number of people have a severe allergic reaction to vaccines called ‘anaphylaxis,’ which can cause swelling, hives, breathing difficulties, lowered blood pressure and, in severe cases, shock. Anaphylactic reactions are very rare – they occur in about one in a million people who have a vaccination.²⁶ In the very rare cases that an anaphylactic reaction happens after a vaccination, it happens shortly after the vaccine is received. That is why you will be asked to wait for a period of time after you get a vaccine so you can receive treatment in case of an allergic reaction.²⁷ Healthcare providers are trained to respond to an anaphylactic reaction.

    If you develop any serious symptoms, call emergency services right away by dialling 911.

  • 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 develop any serious symptoms that you think could be an allergic reaction after your vaccination, call emergency services right away by dialling 911.

  • The only medical reason for a pregnant person not to get vaccinated during pregnancy is if they have had a serious allergic (anaphylactic) reaction to one of these vaccines in the past.

    Talk with your healthcare provider about any allergies you may have and whether you have had a reaction to the flu, Tdap, or COVID-19 vaccines before.

Vaccine Myths vs. Facts

  • There is currently no evidence to suggest that COVID-19 vaccines causes fertility problems in men or women. Current research28-31 shows:

    • No link between COVID-19 vaccines and infertility (problems getting pregnant).

    • No link between COVID-19 vaccines and increased risk of miscarriage or stillbirth.

    • No differences in the chances of conceiving a child between vaccinated and unvaccinated populations.

  • Results from recent studies31-32 show that some people who menstruate may experience some temporary changes in menstruation after getting a COVID-19 vaccine.33 These include:

    • Menstrual periods lasting for a longer time than usual

    • Less time between menstrual periods than usual

    • Bleeding during menstrual periods that is heavier than usual

    These changes are usually small and fix themselves over time in 1 or 2 cycles.34 There are many ideas about why these changes happen, but the exact reasons are still unclear. According to the Society of Obstetricians and Gynaecologists of Canada (SOGC), many things can affect your period, like sleep, stress, sickness, what you eat, and how much you exercise.34 Regardless of these temporary changes in menstruation, there is no evidence that COVID-19 vaccination causes fertility problems.33

  • Some believe that catching a disease and recovering from it provides stronger immunity (protection against a disease) than vaccination. While it's sometimes true that this ‘natural immunity’ can last longer, the dangers of actually getting sick are much greater than any potential risks from vaccination.35

    For example, pregnant people are more likely to get very sick from COVID-19. Having a serious case of COVID-19 in pregnancy increases the risk of complications (problems) like premature birth (birth that happens before 37 weeks of pregnancy) and stillbirth.35 On the other hand, serious reactions to the COVID-19 vaccine during pregnancy are very rare. Common side effects, like redness/soreness where you got the shot, a headache, or a slight fever, are usually mild and disappear in 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.35