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COVID-19 Vaccination for Pregnant Women
 
Kelsey McLaughlin, PhD

This article was last updated on April 16th, 2021.

Currently in Canada, there are four vaccines approved by Health Canada to protect against COVID-19 infection. Three of these vaccines are also approved by The United States Food and Drug Administration.

Pregnant and breastfeeding women were excluded from the clinical trials for the four vaccines approved to protect against COVID-19 infection in Canada. However, Canadian and American authorities recommend that COVID-19 vaccination may be offered to pregnant and breastfeeding women if the benefits of receiving the vaccine outweigh any potential risks. Pregnant and breastfeeding women considering the vaccine are recommended to speak to their health care professional.

Keep reading to learn more about COVID-19 vaccination and pregnancy.
 

What is COVID-19?

COVID-19 is the disease caused by the recently discovered coronavirus, officially named the SARS-CoV-2 virus (read more about COVID-19 and pregnancy here).

 

Since March 2020, scientific studies have shown that:

  • The risk of a COVID-19 positive pregnant woman transmitting the virus to her baby appears to be low (approximately 5%)

  • Pregnant women with COVID-19 are at increased risk of severe illness, relative to non-pregnant women

  • COVID-19 infection in pregnant women increases the rates of preterm delivery, Caesarean sections and delivering a low birthweight infant

  • Breastfeeding is still recommended for pregnant women with COVID-19, with correct hygiene precautions

How do the COVID-19 vaccines work?

The four vaccines approved for use in Canada are produced by Pfizer Canada / BioNTech, Moderna Therapeutics, AstraZeneca and Janssen (Johnson & Johnson).

The purpose of vaccines is to introduce the virus to the body so that the immune system can build up defenses against it. If our body encounters the virus in the future, our immune system can attack the virus and prevent us from getting seriously ill.

The approved Pfizer Canada / BioNTech and Moderna vaccines are mRNA (or messenger RNA) vaccines and the AstraZeneca and Janssen vaccines are viral vector vaccines. None of these vaccines contain a live form of the COVID-19 virus. Vaccines that do contain a live form of the germ of interest are called 'live vaccines', and are not recommended for pregnant women due to potential fetal health risks.

Here are 3 videos explaining how mRNA vaccines work:

Here are 2 videos explaining how viral vector vaccines work:

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COVID-19 vaccine clinical trials

 

Clinical trials were conducted to assess the safety and efficacy of the COVID-19 vaccines.

Pfizer Canada / BioNTech Vaccine Trial

Between July 27 - November 14, 2020, 43,548 people were recruited from 152 sites worldwide and randomized to receive placebo or the COVID-19 vaccine. Key inclusion criteria for this trial included age above 16 years and being in healthy condition. Key exclusion criteria for this trial included a medical diagnosis of COVID-19, medical diagnosis of an immunocompromising condition, and women who were pregnant or breastfeeding. 

The conclusion of this clinical trial was that a two-dose regimen of the Pfizer/BioNTech vaccine (30 μg per dose, given 21 days apart) was found to be safe and 95% effective against COVID-19 infection.

What does ​95% efficacy mean? In this clinical trial, 0.74% of participants who received the placebo became infected with COVID-19, while 0.04% of participants who received the COVID-19 vaccine became infected with COVID-19. To calculate vaccine efficacy, you divide the difference between these infection rates (0.74 - 0.04 = 0.7) by the infection rate in the placebo group (0.74). This equals 0.0945, (0.7 / 0.74), or 95%. This means that people who received the COVID-19 vaccine had a 95% lower risk of becoming infected with COVID-19, relative to people who received the placebo.

Moderna Therapeutics Vaccine Trial

 

Between July 27 - October 23, 2020, 30,420 people were recruited from 99 sites in the United States and randomized to receive placebo or the COVID-19 vaccine. Key inclusion criteria for this trial included age above 18 years and being in healthy condition. Key exclusion criteria for this trial included a medical diagnosis of COVID-19, medical diagnosis of an immunocompromising condition, and women who were pregnant or breastfeeding. 

The conclusion of this clinical trial was that two injections of mRNA-1273 vaccine (100 μg per dose, given 28 days apart) showed 94.1% efficacy at preventing COVID-19 illness in a diverse adult trial population, and no safety concerns were identified, aside from short lived local and systemic reactions.

 AstraZeneca Vaccine Trial

Between April 23 - November 4, 2020, 11,636 people were recruited from the United Kingdom, Brazil and South Africa. Participants were randomized to receive placebo or the COVID-19 vaccine. Key inclusion criteria for this trial included age above 18 years and being in healthy condition. Key exclusion criteria for this trial included a medical diagnosis of COVID-19, medical diagnosis of an immunocompromising condition, and women who were pregnant or breastfeeding. 

The conclusion of this clinical trial was that two injections of ChAdOx1 nCoV-19 vaccine showed 70.4% efficacy at preventing symptomatic COVID-19 illness, and that one injection of ChAdOx1 nCoV-19 vaccine showed 64.1% efficacy. No safety concerns were identified. 

Janssen (Johnson & Johnson) Vaccine Trial


44,325 people were recruited from Argentina, Brazil, Chile, Colombia, Mexico, Peru, South Africa, and the United States. Participants were randomized to receive placebo or the COVID-19 vaccine. Key inclusion criteria for this trial included age between 18 - 55 and being in healthy condition. Key exclusion criteria for this trial included a medical diagnosis of COVID-19, medical diagnosis of an immunocompromising condition, and women who were pregnant or breastfeeding. 

The results from the interim analysis of this clinical trial was that one injection of Ad.26.COV2.S vaccine showed 66% efficacy at preventing moderate and severe COVID-19, and no safety concerns were identified.

Recommendations for COVID-19 vaccination of pregnant or breastfeeding women

As pregnant and breastfeeding women were excluded from the COVID-19 vaccine clinical trials, there is currently no data evaluating the safety and efficacy of the two COVID-19 mRNA vaccines in pregnant and breastfeeding women. Pregnant women have also been largely excluded from clinical trials investigating how to treat patients with COVID-19. This is especially concerning, as pregnant women are considered to be at higher risk of COVID-19 infection, relative to the general population.

On February 18th, 2021, Pfizer/BioNtech announced that they will begin an international clinical trial to evaluate the safety and effectiveness of the COVID-19 vaccine in pregnant women. The trial will first recruit 350 pregnant women between 27 and 34 weeks of pregnancy, before moving onto the larger trial of pregnant women between 24 and 34 weeks of pregnancy.

On March 5th, 2021, the Ontario government identified pregnant women as a high-risk population eligible for COVID-19 vaccination in Phase Two of the provincial vaccination distribution plan. Pregnant women can expect to be vaccinated from April to July 2021.

Below is a summary of the current COVID-19 vaccine recommendations for pregnant or breastfeeding women.

 

The Government of Canada, January 12th, 2021:

  • The COVID-19 vaccine may be offered to pregnant and breastfeeding women if the benefits of receiving the vaccine outweigh any potential risks

  • Pregnant and breastfeeding women considering the vaccine should have a conversation with their health care professional

  • Eligible women who are postpartum or planning to become pregnant should be offered COVID-19 vaccination

Society of Obstetricians and Gynaecologists of Canada, February 1st, 2021:

  • Pregnant or breastfeeding women should be offered vaccination if they are eligible and no contraindications exist

  • The decision to receive the vaccine is based on women’s personal values and an understanding of the benefits and potential risks of vaccination

American College of Obstetricians and Gynecologists, February 4th, 2021:

  • COVID-19 vaccines should not be withheld from pregnant individuals who meet criteria for vaccination

  • COVID-19 vaccines should be offered to lactating individuals similar to non-lactating individuals

  • A conversation between the patient and their clinical team may assist with decisions regarding the use of vaccines for the prevention of COVID-19

Centers for Disease Control and Prevention, February 12th, 2021:

  • People who are pregnant or breastfeeding and part of a priority group recommended to receive the COVID-19 vaccine may choose to be vaccinated

  • A conversation between pregnant patients and their clinicians may help them decide whether to get vaccinated

Special Statement from Society of Obstetricians and Gynaecologists of Canada - April 16th, 2021

As Canada experiences a third wave of COVID-19 infections, there are increasing numbers of very sick pregnant women with COVID-19 requiring hospital admission in Ontario, including ICU admission and mechanical ventilation support.

This is an extremely alarming situation.

The Society of Obstetricians and Gynaecologists of Canada released a special statement calling for the Ontario and other provincial governments to prioritize COVID-19 vaccination for pregnant women over 20 weeks of gestation. 

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Routine Pregnancy Checkup

Consult with your healthcare provider

The Society of Obstetricians and Gynaecologists of Canada recommends that if pregnant or breastfeeding women are considering receiving the COVID-19 vaccine, they should discuss the following with their healthcare provider:

 

  • Risk of COVID-19 infection through the community

  • Risk of COVID-19 infection through the workplace

  • Health conditions that may increase the risk of severe COVID-19 infection, including advanced maternal age, immunosuppressive conditions, diabetes, hypertension, obesity or chronic respiratory conditions

  • Gestational age

  • Available data related to the safety of the vaccine during pregnancy and lactation

  • Data that is not yet available related to the safety and efficacy of the vaccine for pregnant and breastfeeding women

  • Individual beliefs and personal risk assessment of the available data

Why were pregnant and breastfeeding women excluded from these COVID-19 vaccine trials?

 

Pregnant women historically have been excluded from clinical trials. Common reasons for this exclusion include:

 

  • Pregnant women and the developing fetus are typically considered at be vulnerable populations

  • Concern about the complicated physiology of pregnant women

  • Uncertainty whether pregnant women would be willing to participate

 

The exclusion of these women from clinical trials is a challenge, as almost two thirds of pregnant women take medications during pregnancy.

 

There is a push from the scientific community to fairly include pregnant and breastfeeding women into clinical trials.

Summary

Pregnant women are considered to be at higher-risk of COVID-19 infection, relative to the general population. However, pregnant and breastfeeding women were excluded from the clinical trials for the four vaccines approved to protect against COVID-19 infection in Canada. Canadian and American authorities recommend that COVID-19 vaccination may be offered to pregnant and breastfeeding women if the benefits of receiving the vaccine outweigh any potential risks. Pregnant and breastfeeding women considering the vaccine should have a conversation with their health care professional. Clinical trials are ongoing to evaluate the safety and efficacy of the COVID-19 vaccines in pregnant and breastfeeding women.

Disclaimer

Every woman and every pregnancy is unique. Pregnant women should speak to their healthcare provider to ensure maternal and fetal safety. This article is meant to provide readers with current information and opinions. All medical and treatment decisions should be discussed with your healthcare provider.

This article was written by Dr. Kelsey McLaughlin and edited by Dr. Melanie Audette.