Monoclonal Antibody Treatment for COVID-19 in Pregnant People Seems Safe

Monoclonal antibody (mAb) treatment for COVID-19 seems safe during pregnancy, according to a new study that found that adverse events after mAb treatment were mild and rare, but effectiveness was disappointing.

The retrospective, propensity score-matched, cohort study, published in Annals of Internal Medicine, included 944 pregnant participants positive for SARS-CoV-2 infection enrolled at the University of Pittsburgh Medical Center Health System from April 30, 2021, to January 21, 2022.

Investigators evaluated monoclonal antibody treatment with bamlanivimab and etesevimab, casirivimab and imdevimab or sotrovimab compared with no mAb treatment.

“Importantly, mAb treatment seems safe in pregnancy with respect to drug-related adverse events and obstetric-associated outcomes (that is, gestational age at delivery, birthweight, stillbirth, NICU admission, hypertension, severe maternal morbidity, and maternal ICU visit),” the study authors, led by Erin K. McCreary, PharmD, of the University of Pittsburgh School of Medicine, wrote.

Median age was 30 and 79.5% of participants were white. Median gestational age at COVID-19 diagnosis or treatment was 179 days, 69% received sotrovimab, and 62% were fully vaccinated.

Mild drug-related adverse events were reported in eight (1.4%) patients treated with mAb, and no severe reactions related to mAb infusions were reported. Average gestational age at delivery was the same (273 days) among those who received mAb treatment and those who were untreated. Average birthweight was 3290 grams in the treatment group and 3240 among those untreated. There were no deaths in the treatment group and one among those untreated.

“In pregnant persons with mild to moderate COVID-19, adverse events after mAb treatment were mild and rare,” the study authors wrote. “There was no difference in obstetric-associated safety outcomes between mAb treatment and no treatment among persons who delievered.”

The study found no significant differences in COVID-19 outcomes between those treated with mAb and those untreated based on a composite of hospitalizations, emergecy department visits or mortality at Day 28.

“In the total population, the risk ratio for mAb treatment of the composite 28-day COVID-19–associated outcome was 0.71 (95% CI, 0.37 to 1.4). The propensity score-matched risk ratio was 0.61 (95% CI, 0.34 to 1.1),” the authors noted.

The study authors noted that the frequency of hospitalizations and deaths were lower than those of the general population, potentially reflecting the younger age, fewer comorbidities and high rate of vaccination of the study group.

“The neutral finding from effectiveness models may be due to the sample size of the cohort or the absence of a true treatment effect,” the authors wrote.

The study couldn’t evaluate risk-adjusted outcomes for pregnant people with higher risk for COVID-19 complications such as comorbidities or unvaccinated status.

More patients in the treatment group (14, or 2.5%) were hospitalized for non-COVID-19-related issues than in the untreated group (2, of 0.5%), but there was no difference in the propensity-matched cohort.

Limitations of the study included the possibility of underrepresentation of drug-related adverse events, which were patient and parovider reported.

A smaller study conducted at Yale University School of Medicine also found that sotrovimab was safe and well-tolerated among pregnant people and neonates.