Immunological effects and safety of live rotavirus vaccination after antenatal exposure to immunomodulatory biologic agents: a prospective cohort study from the Canadian Immunization Research Network.

Background: People with inflammatory or autoimmune diseases are recommended to continue immunomodulatory biologic agents throughout pregnancy. However, concerns regarding potential immunosuppression in infants exposed to biologic agents have led to recommendations to avoid live vaccines in the first 6-12 months of life. We aimed to examine whether live rotavirus vaccine could be administered safely to infants exposed to biologic agents, assessed in the Canadian Special Immunization Clinic (SIC) Network.

Methods: In this prospective cohort study, infants exposed to biologic agents in utero were referred to one of six SIC sites in Canada for rotavirus vaccination recommendations. Children with other contraindications to rotavirus vaccination or older than 15 weeks were excluded. Clinical and laboratory evaluations were conducted according to a standard clinical pathway. Data were collected for relevant medical history, pregnancy outcomes, biologic agent exposure history, physical examination, laboratory results of the child, SIC recommendations for rotavirus vaccination, rotavirus vaccine series completion, and adverse events after immunisation. After parental consent, deidentified data were transferred to a central database for analysis. Children recommended for rotavirus vaccination were followed up for 8 months after series initiation to ascertain severe and serious adverse events, including severe diarrhoea, vomiting, and intussusception.

Findings: Between May 1, 2017, and Dec 31, 2021, 202 infants were assessed and 191 eligible infants were enrolled (97 [51%] were female and 94 [49%] were male). When including those exposed to multiple agents, the most common biologic agents to which infants were exposed were infliximab (67 [35%] of 191), adalimumab (49 [26%]), ustekinumab (18 [9%]), and vedolizumab (17 [9%]). Biologic agent exposure continued into the third trimester for 178 (93%) infants. No clinically significant abnormalities in lymphocyte subsets, quantitative immunoglobulins, or mitogen responses were detected. After SIC assessment, rotavirus vaccination was recommended for 187 (98%) of 191 infants, all of whom were followed up. By end of follow-up on Aug 19, 2022, 168 (90%) infants had initiated rotavirus vaccination; 150 (80%) completed the series. No serious adverse events after immunisation were reported, but three (2%) infants required medical attention, one for vomiting and change in stools who was subsequently diagnosed with gastroesophageal reflux disease, one for rash on labia unrelated to vaccination, and one for vomiting and diarrhoea associated with a milk allergy.

Interpretation: Findings from this study suggest that lymphocyte subsets and the safety of live rotavirus vaccination are generally not affected by in-utero exposure to biologic agents. Rotavirus vaccination can be offered to infants exposed to anti-TNF agents in utero.

Funding: Public Health Agency of Canada and Canadian Institutes of Health Research through the Canadian Immunization Research Network.