Infants born to COVID-infected mothers are three times more likely to develop respiratory distress

New research from UCLA finds that full-term infants born to mothers infected with COVID-19 during pregnancy were three times more likely to suffer respiratory distress than unexposed infants, even if they were not not themselves infected with the virus. The risk was significantly lower when mothers infected during pregnancy were previously vaccinated.

Researchers found that in utero exposure to SARS-CoV-2 triggered an “inflammatory cascade” in infants, increasing the risk of respiratory disorders that most commonly strike infants born prematurely.

The results are published on January 24 in the journal Natural communications.

“We saw unusually high rates of respiratory distress shortly after birth in full-term babies born to mothers who had COVID-19 during pregnancy,” said lead author Dr. Karin Nielsen, professor of pediatrics in the division of pediatric infectious diseases at the Institute. David Geffen School of Medicine at UCLA. “The mothers had not been vaccinated before contracting COVID, indicating that vaccination protects against this complication.”

To trace the development of respiratory distress after in utero exposure to SARS-Cov-2, researchers conducted a study called proteomics that examines the structure and functions of proteins and how they affect cells. They found that whip-like structures called motile cilia that help clear mucus from the airways did not function normally in exposed infants with respiratory distress. Additionally, infants produced a higher production of antibodies called immunoglobulin E (IgE).

Of the 221 mothers enrolled in the study, 151 (68%) were not vaccinated before infection, with severe or critical COVID-19 disease present in 23 women (16%), compared to only three (4%) vaccinated mothers. The researchers found that 34 (17%) of the 199 exposed infants followed in the study suffered from respiratory distress, which is a very high frequency, because in the general unexposed population, respiratory distress only occurs in 5 to 6 % babies. Among babies with respiratory distress, 21% were born to mothers with severe or critical COVID-19, while only 6% of babies without respiratory distress were born to women with severe illness, a statistically significant result.

Of the 34 infants with respiratory distress, only five (16%) were born to mothers vaccinated before infection, compared to 63 (41%) without respiratory distress, indicating that vaccination had a protective effect. According to the researchers, even one dose of mRNA vaccine before infection significantly reduced the risk of a full-term infant developing respiratory distress.

“Not only do our results show higher rates of DR (respiratory distress) in SEU (uninfected infants exposed to SARS-CoV-2) compared to the general population,” the researchers write, “but we observed more cases of DR at a later stage of gestation. ages than expected, while newborns are likely to have more mature lung anatomy. »

The study has certain limitations. Most participants were enrolled in a large tertiary and quaternary medical center, which typically sees the sickest patients, and several mother/infant pairs were transferred from small community hospitals in the county due to severity of illness, so results may be biased toward more. COVID illness more severe than might be found in the general population.

The researchers did not have data on the effect of COVID infection before vaccination or vaccination after infection, which could affect the severity of maternal illness and its effect on fetal development. Additionally, the results should be interpreted with caution due to the small sample size.