OBJECTIVE. Tetanus, diphtheria, and acellular pertussis vaccination is recommended for adults who are in contact with infants who are younger than 12 months and in the NICU. The objective of this study was to determine the feasibility of tetanus, diphtheria, and acellular pertussis vaccine administration to parents in a tertiary care, level III NICU and to measure its effect on vaccination rates among parents of this high-risk population.
METHODS. For a 4-month period from July to October 2007, all parents of admitted patients were informed of the risks and benefits of tetanus, diphtheria, and acellular pertussis vaccine by placing an information letter at their infant's bedside. All staff were educated about the dangers of pertussis infection and instructed to reinforce the need to obtain vaccination. Immunization was available for 20 hours per day at no cost. Student's t tests were used for data analysis.
RESULTS. During the study period, 352 children (598 eligible parents) were admitted to the NICU at gestational ages ranging from 23 to 42 weeks, and 495 (82.8%) parents were offered the vaccine. Overall vaccination rate was 86.9% (430 parents) of the screened population. Fifty-five (11.1%) parents in the screened cohort refused vaccination, predominately citing pertussis as an insignificant health threat or disbelief in vaccination. There were no differences in vaccination rate on the basis of parental age. No allergic reactions to vaccination were observed. The 54 infants whose parents were not offered vaccine had a significantly shorter length of stay, higher birth weight, and higher gestational age than parents who were offered vaccine.
CONCLUSIONS. Administration of tetanus, diphtheria, and acellular pertussis vaccine in the NICU is an effective means of increasing vaccination rates of parents of this population. Logistic barriers persist when implementing this program for infants with a short (<3-day) length of stay.
Bordetella pertussis is a major cause of morbidity and mortality, particularly in infants who are younger than 4 months.1 Whole-cell pertussis vaccine has controlled disease but not eliminated infection, and the incidence of pertussis is increasing.2–5 Several factors explain the recent increase in infections. Adolescents and young adults are contracting pertussis as a result of waning levels of immunity from the last dose of vaccine at 4 to 6 years of age. Individuals who have close contact with unimmunized or underimmunized infants serve as a reservoir for the pathogen, delineating a cycle of transmission from older adolescents and adults to susceptible children.6
Infants who have chronic respiratory illness and contract pertussis, particularly those discharged from the NICU, exhibit hospitalization rates 3 to 7 times that of other children.7 Neonates with pertussis can present without the disease's characteristic paroxysmal cough and inspiratory whoop. This clinical picture renders diagnosis difficult, delays supportive care and treatment, and leads to longer periods of infectivity and increased morbidity.8–10 Pertussis deaths occur primarily in children who are younger than 6 months, and studies have implicated the pathogen in sudden infant death syndrome.11–14 The immature airways of preterm infants increase the vulnerability of this population to all respiratory pathogens.15–19 Furthermore, preterm infants are at greater risk for immunization delay, impeding the receipt of the multiple doses of vaccine required to confer adequate levels of immunity.20–23 Taken together, these factors underscore the need to protect this patient population.
Tetanus, diphtheria, and acellular pertussis vaccine (TdaP) (Adacel [Sanofi-Pasteur, Lyon, France]) is licensed for administration as a single-dose vaccination to those who are aged 11 to 64 years and were fully immunized in childhood. Clinical studies have shown that the vaccine is safe and confers immunity that lasts up to 8 years.24–28 Multiple studies have also demonstrated that vaccination of adolescents and adults decreases transmission to the unimmunized.29–31 The vaccine is well tolerated, with local injection site reactions documented in ∼10% of recipients and fever occurring in ∼1% to 2% of recipients.32
On the basis of this information, the Centers for Disease Control and Prevention and the Advisory Committee on Immunization Practices recommend 1 dose of TdaP for previously unimmunized new mothers and individuals who have close contact with children who are younger than 12 months and who were fully immunized in childhood.33 These guidelines aim to prevent transmission of infection to high-risk infants.34
Experience with other adult immunizations demonstrates that cost, convenience, and access are barriers to vaccination.35 For specifically addressing these, vaccination of adults at the time their children interact with pediatric care has been proposed.36
Given the availability of 24-hour/day staffing with medical personnel, convenience to parents, and their proximity to a high-risk population, the NICU is considered an ideal arena to immunize eligible parents. Experience with influenza, another respiratory pathogen for which close contacts require vaccination, suggests that postdischarge care of preterm infants can be improved by implementing NICU-based parental vaccination.36 During 1 program, influenza immunization of parents in the NICU resulted in a 94.9% immunization rate and secondarily increased health care worker vaccination rates.37,38 Using the same health care delivery model, administration for TdaP to NICU parents has also been proposed39; however, no study to date has demonstrated the efficacy, feasibility, and parental acceptance of administration of TdaP in the NICU setting. The purpose of the study was to assess the effect of providing TdaP to parents in the NICU on immunization rates.
Between July 1, 2007, and October 31, 2007, parents of infants who were hospitalized in the Stony Brook University Medical Center NICU were eligible for counseling regarding immunization against pertussis with TdaP. Signs posted in the NICU asked parents to discuss pertussis prevention with their physician or nurse. Two weeks before the program's implementation, the nursing staff was educated about the rationale for vaccination of parents. Staff members were encouraged to answer parental questions and notify medical personnel when parents were available at the bedside.
All discussions regarding the risks and benefits of immunization were performed on the basis of a standard outline and included informed consent for administration of TdaP. All conversations took place at the bedside of the hospitalized infant, and all parental questions were answered.
Parents who were considering immunization were given a standardized consent form that asked screening questions to assess contraindications for vaccination (allergy to latex, fever, bleeding disorder, history of seizures, and/or history of Guillain-Barre syndrome). Vaccine lot number, the administering health care worker, parental age, and vaccination date were also recorded. In addition, the infant's date of birth, gestational age, Apgar scores, race, and discharge date were documented. Parents were excluded from the program in cases of neonatal palliative care, paternal noninvolvement, or child-care services custodianship and are collectively classified as unavailable for vaccination.
Survey days were defined as the number of days available for parental screening. This parameter was calculated as the date difference of admission date and discharge date for infants who were born after the start of the study period. Infants who were already in the NICU had the study start date substituted for their admission date. Parents who refused immunization were asked to identify a primary reason for deferral via open field, questionnaire, which was prevalidated on the basis of pilot testing in the newborn well-infant nursery.
After completion of screening, parents were administered TdaP in the deltoid muscle of the nondominant extremity and were not allowed to leave the NICU for 30 minutes subsequent to receipt of vaccine. The vaccine was provided at no cost to NICU parents by the manufacturer (Sanofi-Pasteur).
Responses were tabulated into numerical data and were entered into a Microsoft Access database (Microsoft Corp, Redmond, WA). Analysis was performed by using Student's t test, and P < .05 was considered statistically significant. Data are presented as means ± SD where applicable.
Overall Vaccination Rate
During the study period, 352 infants were admitted to the NICU with an average birth weight of 2627 ± 985 g and gestational age 35 weeks ± 30 days. A schematic outline of the study population is shown in Fig 1. These infants had 640 parents, 598 of whom were available for screening (313 mothers and 285 fathers). Average parental age was 30.6 ± 6.8 years, and no differences in parental age existed between groups. Among available parents, 495 (82.8%) were surveyed and 103 (17.2%) were not surveyed (missed) before discharge. Overall vaccination rate among surveyed parents was 86.9% (430 parents) with 421 parents immunized in the NICU and 9 (1.8%) parents previously immunized elsewhere. The remainder of the surveyed group contained 55 (11.1%) parents who refused vaccination and 10 parents for whom vaccination was medically contraindicated. The primary reasons cited for refusal were consideration of pertussis as an insignificant health threat and overall disbelief in vaccination.
Immunization Pattern and Gestational Age
Immunization trends are detailed in Fig 2. All parents of infants who were <32 weeks' gestation were either vaccinated in the NICU or not eligible for immunization because of palliative infant care, paternal absence, or child protective services involvement. The percentage of parents who were not offered immunization increased with the child's gestational age. Of infants who were born between 32 and 36 weeks' gestation (n = 92), 6 (6.5%) were not offered immunization. For parents of infants who were >36 weeks' gestational age (n = 292), 97 (21.8%) were missed. Parental vaccination rates were significantly greater among those with infants of <32 weeks' gestation (79.3% vs 65.0%; P = .005).
Efficacy of Immunization Delivery
Data for the 421 parents who were immunized in the NICU are summarized in Fig 3. Across all gestational ages, 60.1% of parents were immunized within 72 hours of their infant's NICU admission. Of the remaining 39.9% of parents, approximately half were vaccinated in the proceeding 48 hours and the other half ≥5 days after admission. Vaccination rate within the first 72 hours of admission was significantly higher than in the remaining duration of NICU stay.
Effect of Length of Stay on Immunization Rate
The effect of length of stay on TdaP immunization rate is summarized in Table 1. The average total survey days for the study population was 16.2 ± 27.8. Surveyed parents were available for a longer period of time than missed parents (18.4 ± 22.1 vs 3.7 ± 10.9 days; P < .0001). Of surveyed parents, those who received TdaP were accessible for more days than the parents who refused immunization (19.1 ± 21.4 vs 6.2 ± 10.9 days; P = .003).
Refusal of Vaccination
Fifty-Five parents refused vaccination. Of this group, 25 (45.4%) stated a reason for deferral. Twelve (45%) parents cited disbelief in vaccination, and 10 (40%) did not believe that pertussis was a significant health threat. The infants of parents who refused immunization had higher gestational age, higher birth weight, and shorter survey days compared with immunized parents (37 ± 30 vs 34 weeks ± 30 days [P = .004], 3240 ± 776 vs 2493 ± 986 g [P < .001], and 6.2 ± 10.9 vs 19.1 ± 21.4 days; [P = .003], respectively). Eleven parents had contraindications: 7 (63.6%) had a latex allergy, and 4 (36.4%) had a history of seizures.
Pertussis is a major cause of morbidity in infants who are younger than 1 year, particularly those who have underlying respiratory disease or immunization delay.13 These characteristics put preterm infants at risk for B pertussis infection and prioritize vaccination of their close contacts, who serve as vectors for disease. The increasing number of adult vaccines required to protect children and greater frequency of high-risk preterm births requires evidence-based strategies to assess adult immunization rates.
This study demonstrated that baseline TdaP immunization rates for expectant parents are extremely low: <2% in our survey population. Additional studies are needed to determine the baseline rate of TdaP immunization in the general adult population. Most parents surveyed could not recall their last tetanus booster, underscoring the need for improved record-keeping.
The overall immunization rate of 86.9% demonstrates that NICU administration of TdaP significantly improves immunization rates. This difference is attributable to elimination of barriers to adult vaccination and increased concern for the newborn among parents. Our program provides direct contact between a high-risk population with the convenience of 24-hour/day staffing, favorable conditions for vaccine administration.
A previous study that used the same delivery system for administration of trivalent inactivated influenza vaccine in the NICU resulted in an increased vaccination rate (95%) than that observed in our study.40 We speculate that the seasonality of influenza in conjunction with annual reminders that patients receive about the disease reinforce the need for vaccination and may explain this difference. Because the majority of parents who refused immunization believed that pertussis is an insignificant health risk, education aimed at the severity of this disease in newborns may improve adult vaccination.
Logistic and financial considerations must be resolved regarding reimbursement and administration of TdaP vaccine. Obstetric physicians would be ideal candidates for immunization of pregnant mothers and partners because of their increased interaction during pregnancy, postpartum hospitalization, and follow-up outpatient visits; however, experience with influenza vaccine suggests that these physicians administer vaccine to only 20% of eligible patients, a fact attributed to financial constraints and vaccine storage issues.40–42 In addition, these physicians have been hesitant to vaccinate fathers, preventing the “cocoon” of immunity around the at-risk infant.43 In our study, vaccination of fathers was done after screening, the results of which were placed in the infant's medical chart. Concerns over liability for injury are covered by the Vaccine Injury Compensation Program and required no specific modifications to hospital policy for implementation. Cooperation of all health care contacts, including primary care, obstetrics, newborn nursery, and neonatal intensive care, will be required to increase adult vaccination rates and ultimately reduce the pertussis burden.
Although the strategy was effective at delivering vaccination to parents of high-risk infants, analyses are needed to determine economic feasibility. The cost-effectiveness of adolescent TdaP administration has been well described.44,45 We speculate that cost-savings for this program will depend on regional factors, including baseline incidence of pertussis in the community, proximity of high-risk contacts, smoke exposure, and availability of testing facilities46–48; however, a previous study of NICU-based administration of influenza vaccine suggested that this strategy can be cost-effective once a certain patient population is reached.49 Furthermore, issues involving different financial stakeholders must be addressed. In this model, the hospital bears the cost of immunization and the primary benefit is toward public health; however, it should be noted that because no additional health care workers are needed to implement this policy, cost-effective modeling of NICU-based delivery of vaccine has been shown to reduce costs significantly compared with outpatient immunization programs.49 Additional multicenter trials are required to determine whether this immunization rate is reproducible in other NICUs and sustainable for periods greater than the 4-month trial period.
Delivery of TdaP in this manner has limitations. Seventeen percent of parents were not offered immunization. Most of their infants were term gestation and spent <72 hours in the NICU. To ensure all parents are offered vaccination, several strategies have been proposed, including standing orders and nurse vaccination postpartum.50 This intervention addresses only infants in nurseries, a highly susceptible population but a minority compared with term infants in terms of absolute number of pertussis infections in infants.
Receiving vaccinations was medically contraindicated for 10 adults, which in our study included a history of seizures. Progressive or uncontrolled seizures are a relative contraindication for TdaP administration.51 Well-controlled seizures do not exclude vaccination. Because the NICU is not staffed by physicians who are licensed in adult medicine, our hospital policy requested this difference in the screening questions given to adults for presumed medical and legal reasons, yet this removed a small number of patients from the overall screening pool.
Despite these concerns, given the increased levels of acuity in tertiary care NICUs, vaccination was offered to >80% of parents. This method of immunization delivery represents new potential for preventive health care delivery. Given the vaccination rate and ease of implementation, this program is an ideal candidate for all NICU and well nurseries.
We acknowledge the contribution of Sanofi-Pasteur for donation of vaccine. We also acknowledge Emily Campito, Sarah Li, and the entire Stony Brook University Medical Center NICU staff for assistance in implementing this program.
- Accepted May 30, 2008.
- Address correspondence to Shetal I. Shah, MD, Stony Brook University Medical Center, Health Sciences Center Tower, 11th Floor, 060, Stony Brook, NY 11794. E-mail:
The authors have indicated they have no financial relationships relevant to this article to disclose.
What's Known on This Subject
The Centers for Disease Control and Prevention recommend TdaP administration to close contacts of infants, but evidence suggests problems with current vaccine-delivery strategies. Additional investigation is needed to determine how to vaccinate parents of at-risk infants in the NICU.
What This Study Adds
This program successfully immunized 87% of surveyed parents, introducing a new avenue by which the NICU can improve public health while protecting a vulnerable population. The program is widely reproducible and is an ideal candidate for implementation in other hospitals.
- ↵Cherry JD. The epidemiology of pertussis: a comparison of the epidemiology of the disease pertussis with the epidemiology of Bordetella pertussis infection. Pediatrics.2005;115 (5):1422– 1427
- Centers for Disease Control and Prevention. Pertussis Surveillance Report. Atlanta, GA: Centers for Disease Control and Prevention; 2004
- ↵Lee G, LeBaron C, Murphy T, Lett S, Schauer S, Lieu T. Pertussis in adolescents and adults: should we vaccinate? Pediatrics.2005;115 (6):1675– 1684
- ↵Congeni BL, Orenstein DM, Nankervis GA. Three infants with neonatal pertussis: because of its atypical presentations, pertussis in the neonate may easily be overlooked. Clin Pediatr (Phila).1978;17 (2):113– 118
- ↵Ranganathan S, Tasker R, Booy R, Habibi P, Nadel S, Britto J. Pertussis is increasing in unimmunised infants: is a change in policy needed? Arch Dis Child.1999;80 (3):297– 299
- ↵Heininger U, Kleeman W, Cherry JD; Sudden Infant Death Syndrome Study Group. A controlled study of the relationship between Bordetella pertussis infections and sudden unexpected deaths among German infants. Pediatrics.2004;114 (1). Available at: www.pediatrics.org/cgi/content/full/114/1/e9
- ↵Nicoll A, Gardner A. Whooping cough and the unrecognized post-perinatal mortality. Arch Dis Child.1988;63 (1):41– 47
- Bland RD, Coalson JJ. Chronic Lung Disease in Early Infancy. New York, NY: Marcel Dekker; 2000:13–30
- ↵Batra J, Zangwill K, Eriksen E, Marcy S, Lee M, Ward J. Immunization of preterm infants: a population-based assessment of age-specific vaccine usage [abstract]. Presented at the annual meeting of the Society for Pediatric Research; May, 2005; Washington, DC
- Cherry JD. The science and fiction of the “resurgence” of pertussis. Pediatrics.2003;112 (2):405– 406
- Tran Minh NN, He Q, Ramalho A, et al. Acellular vaccines containing reduced quantities of pertussis antigens as a booster in adolescents. Pediatrics.1999;104 (6). Available at: www.pediatrics.org/cgi/content/full/104/6/e70
- ↵Keitel WA, Muenz LR, Decker MD, et al. A randomized clinical trial of acellular pertussis vaccines in healthy adults: dose-response comparisons of 5 vaccines and implications for booster immunization. J Infect Dis.1999;180 (2):397– 403
- ↵Centers for Disease Control and Prevention. Tetanus acellular pertussis and diphtheria vaccine (TdaP), vaccine information statement 2007. Available at: www.cdc.gov/vaccines/pubs/vis/downloads/vis-tdap.pdf. Accessed March 1, 2007
- ↵Available at: www.cdc.gov/vaccines/recs/schedule/child-schedule.html. Accessed July 16, 2008
- ↵Rennels M, Mesissner C; American Academy of Pediatrics, Committee on Infectious Diseases. Technical report: reduction of the influenza burden in children. Pediatrics.2002;110 (6). Available at: www.pediatrics.org/cgi/content/full/110/6/e80
- ↵Shah SI, Caprio M, Hendricks-Munoz K. Administration of inactivated trivalent influenza vaccine to parents of high-risk infants in the neonatal intensive care unit. Pediatrics.2007;120 (3). Available at: www.pediatrics.org/cgi/content/full/120/3/e617
- ↵Purdy KW, Hay JW, Botteman MF, Ward JI. Evaluation of strategies for use of acellular pertussis vaccine in adolescents and adults: a cost-benefit analysis. Clin Infect Dis.2004;39 (1):20– 28
- Anderson LJ, Parker RA, Strikas RA, et al. Day-care center attendance and hospitalization for lower respiratory tract illness. Pediatrics.1988;82 (3):300– 308
- ↵Holberg CJ, Wright AL, Martinez FD, Ray CG, Taussig LM, Lebowitz MD. Risk factors for respiratory syncytial virus-associated lower respiratory illnesses in the first year of life. Am J Epidemiol.1991;133 (11):1135– 1151
- ↵Broder K, Cortese M, Iskander J, et al. Preventing tetanus, diphtheria, and pertussis among adolescents: use of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccines—recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep.2006;55 (RR-3):1– 34
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