Vaccination Provides Effective Protection Against Increased Risk of Pregnancy Complications due to COVID-19 Omicron Variant
The global network led by the Oxford Maternal and Perinatal Health Institute (OMPHI) at the University of Oxford has published in the journal Lancet the results of the ‘2022 INTERCOVID Study’ conducted in 41 hospitals across 18 countries, including Ann & Robert H. Lurie Children’s Hospital of Chicago. To evaluate the impact of the COVID-19 Omicron variant on maternal and neonatal outcomes the researchers studied 1,545 pregnant women diagnosed with the variant and 3,073 non-diagnosed, concomitant pregnant women as controls. The study was conducted between November 27, 2021, and June 30, 2022, during which time Omicron was the variant of concern. Vaccine effectiveness against the variant was also assessed.
COVID-19 Omicron variant during pregnancy was associated with increased risks of maternal morbidity, severe pregnancy complications, and hospital admission, especially among symptomatic and unvaccinated women. In particular, the risk of preeclampsia was increased among women with severe symptoms. Obese/overweight women with severe symptoms were at the highest risk for maternal morbidity and severe complications.
Vaccinated women were well protected against severe COVID-19 symptoms and complications and had a very low risk of admission to an intensive care unit. Prevention of severe COVID-19 symptoms and complications requires women to be completely vaccinated, preferably with a booster dose as well.
In the study, mRNA vaccines were most effective in preventing severe COVID-19 symptoms and complications, although viral vector vaccines with a booster also provided adequate protection – for at least 10 months after the last dose for both mRNA vaccines and viral vector vaccines with a booster.
José Villar, Professor of Perinatal Medicine at the University of Oxford, who co-led INTERCOVID 2022, says: “We have provided robust, evidence-based information on the increased risk of the COVID-19 Omicron variant during pregnancy for severe maternal complications among symptomatic and unvaccinated women. Of concern is that severe symptoms of the disease occurred in 4% to 7% of unvaccinated women diagnosed with the COVID-19 Omicron variant during pregnancy. The study clearly indicates the need for a complete vaccination course during pregnancy, preferably with a booster, to provide protection for at least 10 months after the last dose. Antenatal services worldwide should strive to include vaccination against COVID-19 in the routine care of pregnant women.”
Aris Papageorghiou, Professor of Fetal Medicine, University of Oxford, who co-led INTERCOVID 2022, says: “Although the Omicron variant may be less harmful than previous variants in the general population, the large proportion of unvaccinated pregnant women worldwide are still at major risk. As it is impossible to predict who will develop severe symptoms or complications, universal complete vaccination is required. Unfortunately, full vaccination coverage among pregnant women is still inadequate even in developed countries.”
Stephen Kennedy, Professor of Reproductive Medicine, University of Oxford, who co-led INTERCOVID 2022, says: “The present study is a shining example of how well-coordinated, multi-national, collaborative research can, in a very short time, provide robust evidence to improve the health of mothers and babies worldwide. The findings from this study and our previous INTERCOVID studies (see below) have contributed to changes in clinical practice and public health policy recommending vaccination for all pregnant women. We hope our work will help to negate the considerable misinformation circulating regarding the pandemic and effectiveness of vaccines.”
Jagjit Teji, neonatologist and site Principal Investigator at Lurie Children’s says: "This study provides robust evidence that vaccination against COVID Omicron variant provides protection for mothers and babies.”
Lurie Children’s study participants were recruited from Northwestern Medicine Huntley Hospital’s Maternal, Newborn and Intermediate Care Nursery areas, where Lurie Children’s neonatologists provide coverage.
Previous publications of the INTERCOVID project
Original findings relating to the first wave of the pandemic were published in April 2021: 'Maternal and Neonatal Morbidity and Mortality Among Pregnant Women With and Without COVID-19 Infection: The INTERCOVID Multinational Cohort Study', can be read in JAMA Pediatrics.
Subsequent research based on the 2020 cohort were published in:
April 2022, 'Effect of prenatal exposure to maternal COVID-19 and perinatal care on neonatal outcome: results from the INTERCOVID Multinational Cohort Study', can be read in the American Journal of Obstetrics and Gynecology.
July 2022, 'Diabetes mellitus, maternal adiposity, and insulin dependent gestational diabetes are associated with COVID-19 in pregnancy: the INTERCOVID study', can be read in the American Journal of Obstetrics and Gynecology
Research at Ann & Robert H. Lurie Children’s Hospital of Chicago is conducted through Stanley Manne Children’s Research Institute. The Manne Research Institute is focused on improving child health, transforming pediatric medicine and ensuring healthier futures through the relentless pursuit of knowledge. Lurie Children’s is ranked as one of the nation’s top children’s hospitals by U.S. News & World Report. It is the pediatric training ground for Northwestern University Feinberg School of Medicine.