COVID-19 Protein Subunit Vaccine (Novavax®)

Last Update: 02 Apr 2025

Medication

Table of content

1. What is it? 2. What are the risks? 3. Breastfeeding/ chestfeeding 4. Fathers and sperm donors 5. Key points

Welcome to our fact sheet on COVID-19 protein subunit vaccine (Novavax®) during pregnancy and breastfeeding. The information given is based on recent research and may change as science progresses. Please remember that this content does not replace personalized advice from your healthcare team.

The HEALTHY PREGNANCY HUB team is collaborating with MotherToBaby to share information on this topic. The original version is available here (May 2023).

Serene, our chatbot, can also answer your questions about medications during pregnancy.

Please note that this fact sheet is based on United States information and has been adapted for Canada, with a review by our Canadian experts. Minor differences may exist between the two countries. Always consult your healthcare professional for information tailored to your situation.

1. What is it?

What is COVID-19?

COVID-19 (short for Coronavirus Disease 2019) is an illness caused by a virus (called SARS-CoV-2). The virus easily spreads from person to person through respiratory droplets that come from our mouths and noses when we breathe, talk, cough, or sneeze. For more information on COVID-19, please see our fact sheet here.

What is a COVID-19 protein subunit vaccine?

COVID-19 protein subunit vaccines help protect against the virus that causes COVID-19. One protein subunit vaccine is approved for use in the United States, made by Novavax. Protein subunit vaccines do not contain live virus that can cause COVID-19. The Centers for Disease Control and Prevention (CDC) have more information about protein subunit vaccines here: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/proteinsubunit.html. The Novavax protein subunit vaccine is not 100% effective at preventing COVID-19, but can greatly reduce the chance of getting very sick from the virus.

Talk to your healthcare provider or visit Health Canada website to learn how to stay up to date with COVID-19 vaccines: https://www.canada.ca/en/public-health/services/diseases/coronavirus-disease-covid-19/vaccines.html. For more information on mRNA COVID-19 vaccines, please see our fact sheet here.

Are COVID-19 protein subunit vaccines recommended for pregnant individuals?

Organizations including CDC, the American Academy of Pediatrics, and the American College of Obstetricians and Gynecologists (ACOG) recommend that pregnant individuals, individuals planning a pregnancy, or individuals who could become pregnant in the future stay up to date on COVID-19 vaccines. The Novavax COVID-19 protein subunit vaccine can be given at any time in pregnancy.

Having a COVID-19 infection while pregnant increases the chance of severe illness and pregnancy complications. Studies have shown that people who are vaccinated are less likely to get COVID-19. If they do get COVID-19, they are less likely to get very sick.

Watch our video to learn more about vaccines during pregnancy!

Learn more

2. What are the risks according to research?

Can getting a COVID-19 protein subunit vaccine make it harder for me to get pregnant?

COVID-19 protein subunit vaccines have not been studied to see if they can make it harder to get pregnant. However, there is currently no evidence that any vaccines cause fertility problems. The American Society for Reproductive Medicine recommends that individuals undergoing fertility treatment stay up to date on COVID-19 vaccines.

I just got a COVID-19 protein subunit vaccine. How long do I need to wait before I get pregnant?

There is no recommendation to wait before trying to get pregnant after getting a COVID-19 protein subunit vaccine.

Does getting a COVID-19 protein subunit vaccine increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have not been done in individuals to see if getting a Novavax COVID-19 protein subunit vaccine during pregnancy could increase the chance of miscarriage.

Does getting a COVID-19 protein subunit vaccine increase the chance of birth defects?

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Studies have not been done in individuals to see if the Novavax COVID-19 protein subunit vaccine could increase the chance of birth defects. Animal studies in rats did not show an increased chance of birth defects.

Fever is a possible side effect of the COVID-19 protein subunit vaccine. A high fever in the first trimester can increase the chance of certain birth defects. Acetaminophen or paracetamol is usually recommended to reduce fever during pregnancy. For more information about fever and pregnancy, see our fact sheet about fever/hyperthermia here.

Does getting a COVID-19 protein subunit vaccine in pregnancy increase the chance of other pregnancy-related problems?

Studies have not been done in females to see if the Novavax COVID-19 protein subunit vaccine could increase the chance of other pregnancy-related problems, such as preterm delivery (before 37 weeks of pregnancy) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). Animal studies in rats did not report other pregnancy problems.

Does getting a COVID-19 protein subunit vaccine in pregnancy affect future behavior or learning for the child?

Based on what is known about this and other vaccines, getting a COVID-19 protein subunit vaccine is not expected to cause long-term problems for the child.

Does getting a COVID-19 protein subunit vaccine during pregnancy protect the baby from the virus after delivery?

It is not known if getting a Novavax COVID-19 protein subunit vaccine during pregnancy would protect the baby from COVID-19 after delivery. Studies looking at another type of COVID-19 vaccine (mRNA) show that the antibodies a person makes after getting the vaccine in pregnancy can pass to the developing baby. Research is needed to know if this is also true for protein subunit vaccines.

3. Breastfeeding/ chestfeeding and COVID-19 protein subunit vaccines

Studies have not been done to see if the Novavax COVID-19 protein subunit vaccine passes into breast milk/ chest milk. However, because it is not a live vaccine that can make copies of itself (replicate) and spread through the body, it is not expected to get into the milk.

Organizations including the Academy of Breastfeeding Medicine and the American Academy of Pediatrics agree that breastfeeding/ chestfeeding individuals can receive COVID-19 vaccines. There is no recommendation to postpone breastfeeding/ chestfeeding or discard milk after getting the Novavax COVID-19 protein subunit vaccine. Talk to your healthcare provider about all your breastfeeding/ chestfeeding questions.

4. Fathers and sperm donors

If a male gets a COVID-19 protein subunit vaccine, could it affect his fertility or increase the chance of birth defects?

COVID-19 protein subunit vaccines have not been studied to see if they can affect male’s fertility or increase the chance of birth defects in a partner’s pregnancy. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures here.

Key points

Protein subunit COVID-19 vaccines (such as Novavax®) are recommended at any stage of pregnancy to help reduce the risk of developing severe forms of COVID-19.
Few studies have been done on protein subunit COVID-19 vaccines during pregnancy. Based on what is currently known, the vaccine is not expected to increase risks, but research is limited.
Breastfeeding is compatible with vaccination, and there is no need to interrupt or delay breastfeeding after receiving the vaccine.
Consult your healthcare provider if you have any questions about vaccines during pregnancy.

References

Please click here for references.

Disclaimer

HEALTHY PREGNANCY HUB provides a source of information validated by health professionals; however, this information is provided for informational purposes only and should not replace professional advice. Medical standards and practices evolve as new data becomes available, so it is imperative to consult your doctor or a qualified health professional for any questions or concerns regarding your health without delay or omission. It is the responsibility of your treating physician or any other health professional, based on their independent experience and knowledge of the patient, to determine the best way to evaluate and treat you.

HEALTHY PREGNANCY HUB does not specifically recommend or endorse any test, practitioner, treatment, product, or opinion mentioned on our platform. HEALTHY PREGNANCY HUB also does not replace the individual patient assessment based on the examination by the healthcare provider of each patient and the consideration of laboratory data and other patient-specific factors.

The use of the information available on our site is at your own risk. No person involved in the creation, production, promotion, or marketing of HEALTHY PREGNANCY HUB guarantees or represents, expressly or implicitly, anything regarding the information available on the platform, which is provided “as it is”. All warranties are expressly excluded and disclaimed, including but not limited to implied warranties of merchantability or fitness for a particular purpose, as well as any warranties arising by law or otherwise in law or from trade or usage. Any statements or representations made by any other person or entity are void.

While consulting symptoms or other medical information on our platform may guide your discussions with your healthcare professional, this information should not be used to make a medical diagnosis or determine treatment. Before making changes to your supplement or medication regimen, please discuss with your medical team or contact 811 (Canada) to ensure the relevance of these changes to your individual situation.

Credits