Rotavirus is a common cause of gastrointestinal morbidity and mortality in the infant population. Live, attenuated, oral vaccination against rotavirus is now recommended for all infants between 6 and 32 weeks of age.1 Furthermore, significant immunity is conferred after only 3 doses.2 Given the prevalence of rotavirus and the logistical constraints to administering all 3 doses prior to 32 weeks' chronologic age, initiation of immunization in the neonatal intensive care unit (NICU) is warranted.3-6 Because of the concerns over use of a live oral vaccine, we propose a practical strategy for administration of a live oral rotavirus vaccine in the NICU.

BACKGROUND

Worldwide, rotavirus contributes significantly to mortality due to infantile diarrhea, contributing to approximately 440,000 deaths annually, mostly in children between 3 and 35 months of age.7-11 In the United States, rotavirus contributes to significant morbidity, resulting in 410,000 physician visits, 205,000 to 272,000 presentations to emergency care, 55,000 to 70,000 hospitalizations, with an estimated annual cost of $1 billion.3-6

By the age of 5, nearly all US children have been exposed to, and infected with, rotavirus.6,8,12-14 Although multiple infections can occur, primary infection correlates with severity of illness and acquisition of immunity, leading to mild or absent disease with subsequent infections.15-17

VACCINE CONSIDERATIONS

Licensed in February of 2006, a live, oral, human- bovine reassortant rotavirus vaccine (RotaTeq, Merck and Co. Inc, West Point, Pennsylvania) has been recommended for routine vaccination by the Advisory Committee on Immunization Practices.1 Administration of the 3-dose series begins at 6 weeks of age, with all 3 doses required prior to 32 weeks.1 Interval doses can be administered between 4 and 10 weeks.1 IgA levels significant to induce immunity were achieved in 93% to 100% of 71,725 patients studied after 3 doses.18 Stool shedding of attenuated virus occurs up to 15 days postvaccination with the greatest risk with the first dose. Although horizontal transmission of attenuated virus was not assessed through epidemiologic studies, it remains a theoretical possibility.

Adverse effects such as risk of intussusception and small bowel obstruction are of concern, given experience with previous rotavirus vaccine preparations.19,20 RotaTeq phase III trials demonstrated no increase risk of intussusception as compared with controls, with 5 cases in the study group versus 6 in the placebo group 42 days' postvaccination.1 At 1 year, 13 intussusception cases occurred in the vaccination group versus 15 in the placebo group.1

Oral live rotavirus vaccination in preterm infants requires special considerations. Premature infants have the potential for increased hospitalization from gastrointestinal viral illness.1 Rotavirus is also a significant nosocomial pathogen in the infant population. Although neonatal-acquired rotavirus can induce a less-severe diarrheal illness, the pathogen has been implicated in premature comorbidities such as necrotizing enterocolitis12 and is associated with distal colonic pneumatosis.12

Live, oral, human-bovine reassortant rotavirus vaccine has not been studied in preterm infants younger than 25 weeks' gestation. A total of 2,070 preterm infants (25-36 gestational age; median 34 weeks) received the vaccine in prelicensure trials. No difference in adverse events was noted in comparison with placebo, and unlike other vaccinations, efficacy was not diminished compared with full-term infants.1

SUGGESTED IMMUNIZATION PROTOCOL

Although Advisory Committee on Immunization Practices recognizes the benefits of immunizing premature infants against rotavirus outweigh the risks, no specific guidelines for a neonatal-based vaccination policy have been proposed. In considering both the risk of viral shedding, noted to be 8.9% after the first dose and the 2-week range over which this can occur, we recommend administration of the vaccine on the day of NICU discharge to minimize the risk of horizontal transmission and nosocomial rotavirus infection in the NICU.

Infants requiring prolonged NICU hospitalization are at significant risk for immunization delay, a deficiency that can persist up to 3 years.2 Unlike other vaccines in the primary immunization series (DTaP, HiB, IPV, PCV, Hep B), oral, live rotavirus vaccine has a narrow clinical window. The 3-dose series must be completed by 32 weeks' chronologic age. Given that doses can be administered at intervals of 4 weeks, we advise immunization on day of discharge of any infant whose chronologic age is between 6 and 12 weeks, noting aggressive immunization strategies (ie, every 4-week dosing) may be required in older age groups.

Efficacy of rotavirus was not diminished with concurrent administration of other vaccines in the primary series; however, these primary immunizations should not be withheld until day of discharge if an infant will require hospitalization beyond 60 days of age.

Rotavirus continues to be a major source of morbidity in the United States. Sequela from the disease, risk of hospitalization, and patterns of transmission are different in preterm infants than in older children.21 These unique features of the disease, particularly the risk for immunization delay, potential for nosocomial rotavirus infection, and NEC must inform any vaccination protocol. Here we propose the first NICU-based protocol for RotaTeq administration. Further experience with the vaccine will allow for modification of this policy to allow for safer administration.

References