Study: Rotavirus vaccinations in NICU pose minimal risk

Rotavirus vaccines do not cause significant outbreaks of the disease in neonatal intensive care units (NICUs), according to a new national study. The research will be presented at the Pediatric Academic Societies (PAS) 2024 Meeting, held May 3-6 in Toronto. 

The findings are important, study authors say, because many NICUs avoid vaccinating against rotavirus due to a theoretical risk of transmission, yet some infants are too old to receive the vaccine once discharged from the NICU. The study conducted at Children’s Hospital of Philadelphia evaluated the risk of vaccinated patients transferring rotavirus to unvaccinated patients in NICUs that administer the vaccine.

According to researchers, preterm infants are at higher risk of the highly contagious but preventable virus, yet few receive the vaccine in hospital settings. The rotavirus vaccine contains a weakened form of the virus to produce a stronger immune response.

The study found that 99.3% of non-vaccinated patients exposed to vaccinated patients did not test positive for the disease. Non-vaccinated patients that contracted rotavirus had no symptoms after 14 days, according to the study.

“Immunization with rotavirus vaccine has been standard practice in the Children’s Hospital of Philadelphia NICU since 2007, and the safety of this practice was supported by retrospective clinical data published in Pediatrics in 2014 – however this remains an uncommon practice in NICUs across the United States,” said Kathleen Gibbs, MD, the study’s lead neonatologist from Children’s Hospital of Philadelphia. “Our yearlong, prospective study done in collaboration with the Centers for Disease Control and Prevention suggests that benefits of vaccinating NICU patients against rotavirus outweigh risks. Inpatient vaccination allows protection of a vulnerable population against a common, preventable cause of severe diarrheal illness.”

The study analyzed 3,448 weekly stool samples from 774 patients between January 2021-January 2022.

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EDITOR:

Morgan Zalot will present “Investigation of Potential Vaccine-strain Rotavirus Transmission in a 100-bed NICU that Routinely Vaccinates: 1-year Surveillance Results” on Saturday, May 4 from 9:00-9:15 AM E.T.

Reporters interested in an interview with Morgan should contact Amber Fraley at amber.fraley@pasmeeting.org.

The PAS Meeting connects thousands of pediatricians and other health care providers worldwide. For more information, please visit www.pas-meeting.org.

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Abstract: Investigation of Potential Vaccine-strain Rotavirus Transmission in a 100-bed NICU that Routinely Vaccinates: 1-year Surveillance Results

Presenting Author: Morgan A. Zalot, MPH

Organization

Children's Hospital of Philadelphia

Topic

Immunizations/Delivery

Background

Many neonatal intensive care units (NICU) avoid vaccinating patients against rotavirus (RV) during hospitalization due to a theoretical risk of transmission of live attenuated vaccine virus to non-vaccine-eligible infants; however, some infants will be age-ineligible by discharge. The 100-bed, level 4 NICU at Children’s Hospital of Philadelphia routinely gives pentavalent RV vaccine (RV5) to eligible infants during admission and does not use post-vaccination contact precautions.

Objective

We conducted surveillance for RV shedding to estimate the risk of vaccine-strain transmission in the NICU.

Design/Methods

From January 2021-January 2022, weekly stool samples were collected throughout the NICU, which has private rooms and shared open pods. Each sample was tested for RV RNA by qRT-PCR. Positive samples were assessed for RV5 strains including repeat testing. Samples were classified as RV5+ if positive in ≥2 of 3 runs, and “possibly RV5+” if positive in 1 of 3 runs. Each sample was categorized non-vaccinated (NV) if collected from an unvaccinated infant, or post-vaccine. Each NV stool was assumed to contribute one patient-day at-risk for RV5 strain transmission. Transmission was defined as RV5 strain detection in a NV stool. Chart review and bed location analysis were performed for transmission events.

Results

During surveillance, 226 RV5 doses were given. We collected 3471 stool samples from 774 patients, including 2252 NV samples during an at-risk period from 686 patients (Fig.). Most (681/686, 99.3%) patients who contributed a NV sample never tested RV5+; 5 (< 1%) tested RV5+ or possibly RV5+. Four of the 5 patients had RV5 detection in the first tested stool (collected 1-5 days post-admission); one had initial detection in the second stool (6 days post-admission). The estimated rate of RV5-strain transmission to unvaccinated infants was 5/2252 patient-days at risk (2.2 events per 1000 patient-days [95% CI: 0.7-5.2]).

Investigations of transmission events (Table) to identify most proximal potential exposures to vaccine-strain RV revealed 4/5 patients had a healthcare worker (HCW) in common with a recently vaccinated patient (received an RV5 dose within preceding 48 hours of shared HCW), including one in an adjacent bed. Chart review indicated no symptoms of gastroenteritis or unexplained fever in transmission case-patients in the 14 days surrounding collection of the RV5+ stool.

Conclusion(s)

Vaccine-strain rotavirus transmission in the NICU was rare and without clinical consequences. The benefits of administering RV5 in NICUs appear to outweigh risks.

Tables and Images

Figure: Flow diagram of study cohort

Table: Exposure investigation details for 5 possible transmission case-patients (TCPs)