The risk of preterm birth was 37% higher for mothers involved in a phase 3 respiratory syncytial virus maternal vaccine trial than the control group in a clinical trial led by pharmaceutical giant GSK and researchers from Durham, N.C.-based Duke University School of Medicine.
While the vaccine was shown to reduce the risk of babies contracting RSV, they stopped enrollment in the trial early due to the safety concerns, researchers recount in an analysis published March 14 in the New England Journal of Medicine.
The defunct phase 3 trial enrolled 5,328 pregnant women between 18 and 49 years of age and 5,233 infants between November 2020 to February 2022, when the trial was halted.
"The results of this trial, in which enrollment was stopped early because of safety concerns, suggest that the risks of any and severe medically assessed RSV-associated lower respiratory tract disease among infants were lower with the candidate maternal RSV vaccine than with placebo but that the risk of preterm birth was higher with the candidate vaccine," the authors wrote.