THE FREQUENCY OF RESPIRATORY SYNCYTIAL VIRUS IN HIGH RISK INFANTS AND THE ROLE OF PALIVIZUMAB IN PREVENTION OF INFECTION

Palivizumab (Synagis[R]) is a monoclonal antibody that has been recommended for prophylaxis of respiratory syncytial virus (RSV) for infants with gestational age [is less than or equal to] 32 weeks and for children with bronchopulmonary dysplasia [is less than] 24 months (AAP Guideline, 11/ 98). The risk of RSV disease is unclear in borderline preterm (32-35 weeks gestation), and whether they may benefit from palivizumab prophylaxis. Methods: Premature and term infants born between 5/98 and 1/99 who are cared for in a single pediatric practice at Thomas Jefferson University Hospital were enrolled in this institutional board approved study. Data were collected by interview of the primary caregiver at office visits and/or by telephone, or by chart review. Parameters included were birth weight, gestational age (GA), race, gender, family history of allergies or asthma, exposure to smoke, child care arrangement and number of household members. Data included number of additional office visits (OFC), emergency room visits (ER), and hospitalizations (HOSP). Infants were divided into 3 groups: [is less than or equal to] 32 weeks GA who received palivizumab in accordance with AAP guidelines (Group 1, n = 23), 32-35 weeks GA (Group 2, n 2624), and term (untreated) infants used as a geographic control (Group 3, n=50). The goal was to compare the number of OFC, ER, and HOSP between these groups. In addition, to assess treatment compliance, short-term, and long-term folllow-up of the palivizumab-treated cohort. Results: Preliminary data reveal 3 groups that are similar in gender, race, use of out-of-home daycare, exposure to passive smoke, and family history. With 80% of the patients evaluated, the rate of HOSP with RSV is 4.3% in Group 1, 4% in Group 2, and 9% in Group 3. In addition, the rate of RSV-related OFC and ER is 13% in Group 1, 13.3% in Group 2, and 12.2% in Group 3. Conclusions: Although the sample size in the study's first season lacks the power to obtain statistical significance, the cohort of 32-35 weeks GA infants did not have more OFC, ER, or HOSP than geographic controls of otherwise healthy term infants. Also, treated infants demonstrated excellent compliance; with all subjects receiving 4-5 doses of palivizumab. Our preliminary results are consistent with observations in other studies, demonstrating a [is greater than] 50% reduction in RSV-related hospitalizations in infants treated with palivizumab compared to a geographic cohort of infants cared fo