New UCLA-led research finds that infants born full term to mothers who were infected with COVID-19 during pregnancy had three times the risk of having respiratory distress compared with unexposed infants, even though they themselves were not infected with the virus. The risk was significantly lower when the mothers infected during pregnancy were previously vaccinated.
The researchers found that in-utero exposure to SARS-CoV-2 sparked an “inflammatory cascade” in the infants, increasing the risk of a breathing disorder that most often strikes prematurely born infants.
The findings were published January 24 in the peer-reviewed journal Nature Communications.
To trace how respiratory distress develops following in-utero exposure to SARS-Cov-2, the 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 respiratory tract did not function normally in the exposed infants stricken with respiratory distress. In addition, the infants had higher production of antibodies called immunoglobulin E (IgE).
Of the 221 mothers enrolled in the study, 151 (68%) were unvaccinated prior to infection. with severe or critical COVID disease present in 23 women (16%), compared with only 3 (4%) of vaccinated mothers. The researchers found that 34 (17%) of 199 exposed infants followed in the study had respiratory distress, which is a very high frequency, as in the general, unexposed population respiratory distress happens in 5% to 6% of babies only. Twenty-one percent of babies with respiratory distress were born to mothers with severe or critical COVID-19, while only 6% of babies without respiratory distress were born to women with severe disease, a finding that was statistically significant.
Of the 34 infants with respiratory distress, only 5 (16%) were born to mothers vaccinated prior to infection, compared to 63 (41%) without the breathing disorder, indicating that vaccination had a protective effect. According to the researchers, even one mRNA vaccine dose prior to infection significantly reduced the odds that a full-term infant would develop respiratory distress.
