CITF-funded findings on COVID-19 and vaccine effects on pregnancy and infants

CITF-funded studies have confirmed that COVID-19 is indeed more severe in many pregnant people, and that pregnant people and their babies respond just as well as the general population to COVID-19 vaccines. Here, we summarize results from the five presentations given during the breakout session “COVID-19 and vaccine effects on pregnancy and infants” at the CITF Scientific Meeting in Vancouver, March 8-10, 2023. The study teams presented a broad spectrum of population research on COVID-19 and pregnancy, addressing infections, outcomes, vaccine safety, and vaccine uptake.

1. Presenter and CITF PI Dr. Deborah Money: Canadian surveillance of COVID-19 in pregnancy: Epidemiology, maternal and infant outcomes

CANCOVID-Preg was a prospective, observational surveillance program for SARS-CoV-2-affected pregnancies in Canada. The aim of the program was to provide Canadian data on COVID-19 during pregnancy to support optimal care and public policy.

• SARS-CoV-2 infection during pregnancy was significantly associated with increased risk of adverse maternal outcomes (including hospitalizations, intensive care unit admissions, and cesarean deliveries) and preterm births.
• A pregnant individual of African, East Asian, or Middle Eastern ethnicity was even more at risk of hospitalization or intensive care unit (ICU) admission from SARS-CoV-2 infection than a pregnant person of other ethnicities.

2. Presenter Dr. Eszter Török and CITF PI Dr. Deshayne Fell: Pregnancy, fetal, and newborn outcomes following a first booster dose of COVID-19 vaccine during pregnancy

The aim of this study was to assess the risk of adverse pregnancy, fetal, and neonatal outcomes when a vaccinated person had their third COVID-19 vaccine dose during pregnancy. Data were collected from the Better Outcomes Registry & Network (BORN) Ontario Registry.

• Individuals who were 30 years of age and older, non-smokers, and/or living in higher income neighborhoods were more likely to receive a third COVID-19 vaccine dose during pregnancy.
• Getting the third COVID-19 vaccine dose during pregnancy was not associated with any increased risk of pregnancy complications including: postpartum hemorrhage (heavy bleeding after giving birth), chorioamnionitis (an infection of the placenta and the amniotic fluid), cesarean and emergency cesarean delivery, placental abruption (when the placenta separates from the inner wall of the uterus before birth), and gestational hypertensive disorder (high pressure during pregnancy).
• Getting the third COVID-19 vaccine dose during pregnancy was not associated with any increased risk of adverse fetal and neonatal outcomes including: small-for-gestational age and preterm birth.

3. Presenter Dr. Sarah Jorgensen and CITF PI Dr. Jeffrey Kwong: Effectiveness of maternal mRNA COVID-19 vaccination during pregnancy and postpartum against Delta and Omicron SARS-CoV-2 infection and hospitalization in infants younger than 6 months of age: A Canadian Immunization Research Network (CIRN) study

This study estimated how effective mRNA COVID-19 vaccines were in protecting infants 6 months old and under from Delta and Omicron infections and hospitalizations when the parent had taken the vaccine during pregnancy, as well as when they had taken it after pregnancy.

• Two vaccine doses during pregnancy were 45% effective at preventing an Omicron infection in infants and 53% effective at preventing hospital admission.
• Three vaccine doses during pregnancy were 73% effective at preventing Omicron infection in infants and 80% effective at preventing hospital admission.
• Two vaccine doses taken by the parent after pregnancy were 13% effective at preventing Omicron infection in infants and 36% effective at preventing hospital admission.

4. Presenter Dr. Ana Citlali Marquez and CITF PI Dr. Deborah Money: Analysis of SARS-CoV-2 seroprevalence using residual antenatal serum samples in British Columbia

The objective of this study was to use residual antenatal serum samples as a proxy to track the progression of SARS-CoV-2 in the population of British Columbia. ​

• During the Omicron wave, SARS-CoV-2 IgG levels indicative of infection increased in the samples of women in their first trimester.
• There were no significant differences in SARS-CoV-2 infection levels, as measured by SARS-CoV-2 nucleocapsid protein, detected from January to December 2022 among populations of different health authorities, including Fraser, Interior/Island/Northern, and Vancouver Coastal.
• There were no significant differences in SARS-CoV-2 infection levels detected from January to December 2022 among different age-groups including 16-27 years, 28-37 years, and 38 years and older.

5. Presenter Dr. Elisabeth McClymont and CITF PI Dr. Deborah Money: Reactogenicity, pregnancy outcomes, and SARS-CoV-2 infection following COVID-19 vaccination during pregnancy in Canada

This study looked at self-reported reactions to COVID-19 vaccines in pregnant people, pregnancy outcomes, and whether pregnant people got SARS-CoV-2 infections following COVID-19 vaccination administered at all stages of pregnancy in Canada.

• Pregnancy outcomes (including spontaneous abortion, preterm birth, stillbirth, and pre-eclampsia) were similar in individuals who were vaccinated compared to those not vaccinated during pregnancy.
• Infant outcomes including jaundice (condition where the whites of the eyes and mucous membranes turn yellow because of a high level of bilirubin, a yellow-orange bile pigment), seizure, hypoglycemia (low blood sugar), and fever were similar in babies whose pregnant parent was vaccinated and in those whose parent was not vaccinated during pregnancy.