New research, to be presented at this year’s European Congress on Clinical Microbiology and Infectious Diseases (ECCMID) in Lisbon, Portugal (April 23-26), suggests that pregnant women are at significantly higher risk of serious illnesses when they are pregnant become infected with the virus. 19 than non-pregnant women of childbearing age. The results are independent of important risk factors such as age, underlying diseases, vaccination status and type of infection.
Importantly, the results also suggest that women are half as likely to be hospitalized after a single dose of the COVID-19 vaccine, and even less likely to be hospitalized after two or more doses. Similarly, women were half as likely to be admitted to the intensive care unit (ICU) if they received one dose of the vaccine and even less likely if they received two or more doses.
The timed cohort study by Kiera Murison and colleagues at the University of Toronto, which included information on more than 13,600 women from the Ontario Case and Contact Management Database, is unique in that each pregnant woman affected by COVID-19 was compared to five unaffected – Pregnant women of childbearing potential with COVID-19 matched by date of positive test for SARS-CoV-2 infection.
The researchers say the results underscore the importance of getting vaccinated against COVID-19 for pregnant women.
Pregnancy is associated with an increased susceptibility to the serious consequences of infectious diseases, both for the mother and the developing child. The COVID-19 pandemic can have significant health consequences for pregnant women, who may also be more reluctant to get vaccinated than non-pregnant individuals.
To assess the extent to which the increased severity of COVID-19 outcomes can be attributed to pregnancy, between March 16, 2020 and January 4, 2022, the researchers analyzed data from a population-based SARS-CoV-2 case file in Ontario that Includes records for over 1 million confirmed cases of COVID-19 in the Canadian province of Ontario (population over 14 million).
Because the likelihood of vaccination and the dominant viral strains in the circulation changed over time, researchers conducted a time-matched cohort study that assessed the relative risk of major disease in matched pregnant women with COVID-19 with women infected with COVID -19 were infected of childbearing age (10 to 49 years) by date of laboratory-confirmed SARS-CoV-2.
Modeling was used to estimate the risk of major COVID-19-related outcomes (hospitalization and ICU admission) in pregnant women and non-pregnant controls after adjustment for age, other diseases, health worker status, vaccination, and infectious variant. Fortunately, there were fewer than five maternal deaths related to COVID-19 during the study, so the risk of death during pregnancy could not be assessed.
The analyzes found that while pregnant women were only half as likely to be infected with SARS-CoV-2 compared to the general population (likely due to greater caution, social distancing and other measures), they were almost five times more likely to be infected with SARS-CoV-2 SARS-CoV-2. were hospitalized with COVID-19 and were more than six times more likely to require intensive care than their non-pregnant peers (see figure and table in Editor’s Notes).
Further analysis comparing women with similar comorbidities found that healthy pregnant women were more than five times more likely to be hospitalized than healthy non-pregnant women; while pregnant women with underlying conditions were only twice as likely to be hospitalized as their non-pregnant counterparts with comorbidities.
“These results suggest that in otherwise healthy women, pregnancy itself appears to be a factor that increases disease severity, while in women with comorbidities it is one of many factors that increase risk,” says Murison. “Our findings underscore the need for clear and accurate information to reassure pregnant women and address concerns about the safety of COVID-19 vaccines. »
This is an observational study and therefore cannot determine a cause. And the researchers concede that they weren’t able to examine the relative virulence of the recent omicron variant during pregnancy, or rule out the possibility that other unmeasured factors, such as the presence of underlying medical conditions, might affect the results .