Live Rotavirus Vax Safe for Babies of Biologic-Treated Moms

More evidence suggests there is little risk in administering the live rotavirus vaccine to the babies of mothers on biologics during pregnancy for inflammatory bowel disease (IBD).

No adverse events or impairment of the immune system emerged in babies at 7 days, 1 month, and 9 months postvaccination, in findings from a small Canadian study published in Clinical Gastroenterology and Hepatology.

The study found normal extended immune function testing in infants despite third-trimester maternal biologic therapy and regardless of circulating drug levels. The data provide reassurance about live rotavirus vaccination in this population and may also offer insights into the safety of other live vaccines in biologic-exposed individuals, wrote investigators led by gastroenterologist Cynthia H. Seow, MD, a professor in the Cumming School of Medicine at the University of Calgary in Calgary, Alberta, Canada.

“Despite the well-established safety and effectiveness of non-live vaccination in individuals with IBD, including those on immunomodulators and biologic therapy, vaccine uptake in pregnant women with IBD and their infants remains suboptimal,” Seow said in an interview. This largely arises from maternal and physician concerns regarding transplacental transfer of IBD therapies and their impact on the safety of vaccination.

“These concerns were heightened after reports emerged of five fatal outcomes following the administration of the live Bacille Calmette-Guérin [BCG] vaccine in biologic-exposed infants. However, it had already been reported that inadvertent administration of the live oral rotavirus vaccine, a very different vaccine in terms of target and mechanism of action, in biologic-exposed individuals had not been associated with significant adverse effects,” she said.

They undertook their analysis with the hypothesis that vaccination would carry low risk, although the live oral vaccine is not currently recommended in biologic-exposed infants. “Yet rotavirus is a leading cause of severe, dehydrating diarrhea in children under the age of 5 years globally, and vaccination has led to significant reductions in hospitalizations and mortality,” Seow added.

Provision of the vaccine to antitumor necrosis factor (TNF)-exposed infants has been incorporated into the Canadian Public Health and immunization guidelines, as the majority of the biologic-exposed infants were exposed to anti-TNF agents, she added. “And with collection of further data, we expect that this will be extended to other biologic agent exposure. These data are important to pregnant women with IBD as they help to normalize their care. Pregnancy is difficult enough without having to remember exceptions to care,” Seow noted.

“Before some of the studies came out, broad guidelines recommended that live vaccines should not be used in biologic-exposed infants, but this had been thought to be overly zealous and too conservative, and the risk was thought to be low,” said Elizabeth Spencer, MD, an assistant professor of pediatrics in the Division of Pediatric Gastroenterology at the Icahn School of Medicine at Mount Sinai in New York City, in an interview. Spencer was not involved in the Canadian study.

“At our center, we had some moms on biologics during pregnancy who forgot and had their babies vaccinated for rotavirus, and the babies were all fine,” she said.

The safety of this vaccine has been confirmed by several small studies and recently the PIANO Helmsley Global Consensus on Pregnancy and Inflammatory Bowel Disease, which was presented at Digestive Disease Week 2024. The consensus encompasses preconception counseling and the safety of IBD medications during pregnancy and lactation.

“Another concern, however, was that giving a live GI bug like rotavirus to babies might overstimulate their immune systems and provoke IBD,” Spencer added. “While a number of population-based studies in the US and Europe showed that was not the case, at least in the general population, there was a suggestion that down the road, vaccination might be mildly protective against IBD in some cases.”

She added the caveat that these studies were not done in IBD mothers and their babies, who might be inherently at greater risk for IBD. “So, a question for future research would be, ‘Is immune stimulation of the gut in IBD moms and their babies a good or a bad thing for their gut?'”

Spencer conceded that “the data present a bit of a blurry picture, but I think it’s always better just to vaccinate according to the regular schedule. The current data say there is no added risk. but it would be nice to look specifically at risk in moms with IBD and their children.”

The Study

The prospective cohort study is a substudy of a larger 2023 one that included biologic use in a range of maternal illnesses, not just IBD.

For the current study, Seow and colleagues identified 57 infants born to 52 mothers with IBD attending a pregnancy clinic at the University of Calgary in the period 2019-2023. Almost 81% of the mothers had Crohn’s disease, and the median duration of IBD was 10 years. The median gestational age at delivery was 39 weeks, and almost 60% of deliveries were vaginal. The infants had been exposed in utero to infliximab (n = 21), adalimumab (n = 19), vedolizumab (n = 10), and ustekinumab (n = 7) in the third trimester.

The 57 biologic-exposed infants underwent standardized clinical assessments, drug concentration, and immune function testing. The live oral rotavirus vaccine series was provided to 50 infants, with the first dose at a median of 13 weeks of age. Immunologic assessments validated for age were normal in all infants despite median infliximab concentrations of 6.1 μg/mL (range, 0.4-28.8 μg/mL), adalimumab concentrations of 1.7 μg/mL (range, 0.7-7.9 μg/mL), ustekinumab concentrations of 0.6 μg/mL (range, 0-1.1), and undetectable for vedolizumab at 10.7 weeks of age.

As anticipated, infant immune function was normal regardless of circulating drug levels.

The overall message, said Seow, is “healthy mum equals healthy baby. Be more concerned regarding active inflammation than active medications. In almost all circumstances, treat to target in pregnancy as you would in the nonpregnant state.” She added, however, that further studies are needed to determine the safety and optimal timing of other live vaccines, such as the BCG, in the presence of biologic therapy.

This study was funded by the Alberta Children’s Hospital Research Institute. 

Seow reported advisory/speaker’s fees for Janssen, AbbVie, Takeda, Pfizer, Fresenius Kabi, Bristol Myers Squibb, Pharmascience, and Lilly, as well as funding from Alberta Children’s Hospital Research Institute, Crohn’s and Colitis Canada, the Canadian Institutes of Health Research, and Calgary Health Trust, and data safety monitoring from New South Wales Government Health, Australia. 

Multiple coauthors disclosed similar consulting or speaker relationships with private industry. 

Spencer had no competing interests with regard to her comments.